Liste des publications - supcom.mincom.tn · Liste des publications [1] [2] ... [email protected]; mohamed.mabrouk@isetc 130, CNRS-INPG-UJF, Minatec-3, Grenoble Ce RFID reader at

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Liste des publications

[1]

[2]

M. Dhaouadi, M. Mabrouk, T.P. Vuong, A.C. de Souza and A. Ghazel,

"A capacitively-loaded loop antenna for UHF near-field RFID reader applications",

IEEE Radio Wireless Week, RWW 2015, 25 - 28 January, 2015, San Diego,

California, USA. (Dans la liste de l’EDTIC)

M. Dhaouadi, M. Mabrouk, T.P. Vuong, A.C. de Souza and A. Ghazel, "UHF Tag

antenna for near-field and far field RFID applications", The 15th annual IEEE Wireless

and Microwave Technology Conference ,WAMICON 2014, June 6, 2014, Tampa,

Florida, USA. (Dans la liste de l’EDTIC)

[3] M. Dhaouadi, M. Mabrouk, T.P. Vuong, D.Hamzaoui and A. Ghazel, "Chip Impedance

Matching For UHF-Band RFID TAG", The 7th European Conference on Antennas and

Propagation, EuCAP 2013, 8-12 April 2013, Gothenburg, Sweden.

[4] M. Dhaouadi, M. Mabrouk, S. Tedjini and A. Ghazel, "A Broadband Antenna for

Passive UHF RFID Tags", International Conference on Information Processing and

Wireless Systems, IP-WiS 2012, March 16,17 and 18 2012, Sousse, Tunisia.

[5] M. Dhaouadi, M. Mabrouk, S. Tedjini and A. Ghazel, " ELECTROMAGNETIC

ANALYSIS OF UHF NEAR FIELD RFID TAG ANTENNA", XXX General

Assembly and Scientific Symposium, URSI GASS, august 2011, Istanbul, Turkey.

[6] M. Dhaouadi, M. Mabrouk, S. Tedjini and A. Ghazel, "Influence of magnetic near-field

on UHF RFID Tag", The third international EURASIP workshop on RFID technology,

EURASIP RFID 2010, 6-7 september 2010, La Manga del Mar Menor, Cartagena,

Spain.

[7] M. Dhaouadi, M. Mabrouk, S. Tedjini and A. Ghazel, "Magnetic antenna for

near-field UHF RFID Tag", 18th International Conference on Microwave, Radar and

Wireless Communications MIKON 2010, June 14-16 June 2010, Vilnius, Lithuania.

[8] M. Dhaouadi, M. Mabrouk, S. Tedjini and A. Ghazel "Magnetic feeding for

UHF-RFID Tags Antenna", IEEE International Conference on RFID

(IEEE-RFID-2010), 14-15 April, 2010, Orlando (FL), USA.

A capacitively-loaded

Abstract— In this work, we presecapacitively-loaded loop antenna for Ultra(UHF) near-field radio frequency identreader applications. The antenna structurefolded-dipole loop structure with twminiaturized to small size of 40 × 36 × 1.applications. Our bandwidth measuremprototype is 10.5 MHz from 865-875.5 MHcoefficient less than 10 dB, which covers allBand (865-868 MHz). Furthermore, a cthrough two C-arms is created inside the lhas an effect of increasing the electrical lengstructure. Therefore, the proposed antennato different UHF RFID bands by varparameters. The measured reading capabiliis up to 7 cm for near-field RFID measurements show this antenna is sunear-field RFID reader applications. Index Terms—reader antenna, Near-field, (RFID).

I. INTRODUCTION

Radio-Frequency IDentification (RFIDidentification method, relying on storinretrieving information using devices calletransponders [1]. UHF near-field RFID syon inductive coupling between the readMost of the near field UHF RFID antenrectangular or circular loops, because tantennas are able to produce a uniform mthe region around the antenna. Today it appears that one of the limisystems is they do not operate correctly a(near field). To resolve this problem, sobeen reported to address the antennas desiTag for UHF near-field RFID applicationthe authors of [2] have proposed two coUHF Tags based on a split ring resonatorfor UHF near-field RFID application.difference of the magnetic field distributbetween RFID Tag antennas using indufeed and T-match configuration was also Similar to the near-field UHF RFID near-field RFID reader antenna must bincreasing the magnetic field between the

M. Dhaouadi1, M. Mabrouk1, Mem

1 GRESCOM E-mail: mondher.dhaou

2 IMEP-LAHC - UMR 5

loop antenna for UHF near-fieldapplications

ent a compact a-High Frequency tification (RFID) e is composed by

wo C-arms and .6 mm3 for RFID

ment of antenna Hz with reflection l of Europe RFID apacitive loading loop antenna and gth of the antenna a can be dedicated rying the C-arm ity of our antenna

Tag, and our uitable for UHF

RF identification

) is an automatic ng and remotely ed RFID Tags or ystems are based

der and the Tag. nnas should have these small loop magnetic field in

itations of RFID at short distances ome works have ign of reader and ns. For example,

ompact near-field r (SRR) structure Moreover, the tion in near-field uctively coupled presented in [3]. Tag, the UHF

be designed for two antennas. In

[4], a reader loop antenna operatingproposed to meet the near-field RFthe proposed compact near-field based on split-ring-resonator (miniaturized to a special small sapplication. In [6], the author pnear-field antenna for UHF RFID re In our paper, we present a caantenna for UHF near-field Rcommercial simulator, HFSSTM hanalyze the near-field characteristicThe proposed antenna also has thsize (40 × 36 mm2), low cost, near-field RFID reader applicationmeasured results for this antenna are

II. ANTENNA STRUCTU

Several reader antennas for Uapplications have been designed. Idipole antenna for UHF near-fproposed, simulated, fabricated andantenna is composed of a capacdipole antenna in a circular form [7capacitive loading is consisting of two arms of the antenna. The struantenna is shown in Fig. 1. The anFR4 substrate (thicknes H 1.6 mconstant ε 4.4 , and loss tangean overall size of 40 × 36 mm2.

Fig. 1. Proposed loop anten

mber, IEEE, T.P. Vuong2, Senior Member, IEEEA. Ghazel1, Senior Member, IEEE

Lab, SUPCOM, University of Carthage, [email protected]; mohamed.mabrouk@isetc130, CNRS-INPG-UJF, Minatec-3, Grenoble Ce

d RFID reader

g at the UHF band was ID applications. In [5], reader antenna were

(SRR) structure and size for mobile RFID proposed a dual-loop

eaders. apacitively-loaded loop RFID applications. A has been employed to s of the reader antenna.

he advantages of small and suitable to UHF

ns. The simulated and e presented below.

RE DESIGN

UHF near-field RFID In this paper, a folded field RFID reader is d tested. The designed citively-loaded folded-] with two C-arms. The a narrow gap between

ucture of the designed ntenna is fabricated on mm , relative dielectric ent tanδ 0.02 ) with

nna structure

E , A.C. de Souza2, and

a com.rnu.tn edex 1, France

On the top view of substrate, the dimendipole loop antenna are L1=40 mm, L2=6mm, W2=1 mm, W3=0.46 mm, W4=2 mR2=9 mm, R3=12.5 mm, R4=13.9 mm, R5mm.

III. SIMULATED AND EXPERIMENTAL

The proposed antenna with a FR-4 substras shown in Fig. 2.

Fig. 2. Photograph of antenna prot

Fig. 3 shows good agreement betweeand simulated return loss of the ante0.46 mm. The measured return loss of 15at the frequency of 870 MHz. The frequenmeasured 10 dB return loss is 865–875covers the 865-868 MHz band in Eapplications.

8 0 0 8 5 0 9 0 0

-1 8

-1 6

-1 4

-1 2

-1 0

-8

-6

-4

-2

0

2

Ret

urn

loss

(dB)

F re q u e n c y (M H z )

Fig. 3. Simulated and measured return loss

antenna

A capacitive load is made inside the lotwo C-arms formed in the center odecreasing the resonance frequency electrical length of the structure. Figsimulated return loss of the antenna with v

nsions of folded-6.12 mm, W1=36 mm, R1=4.8 mm,

5=15 mm, R6=16

L RESULTS

rate is fabricated

totype

en the measured enna with W.6 dB is obtained ncy range for the 5.5 MHz, which European RFID

9 5 0 1 0 0 0

m easu red s im u la te d (H F S S )

)

of the proposed

op antenna using of the antenna,

and increasing g. 4 shows the various W .

0 ,8 0 0 ,85 0 ,9 0-2 0

-1 8

-1 6

-1 4

-1 2

-1 0

-8

-6

-4

-2

0

2

Ret

urn

loss

(dB

)

F re q u e n cy

W 3 = 0 ,4 m m W 3 = 0 ,4 5 m m W 3 = 0 ,7 m m W 3 = 1 ,2 m m

Fig. 4. Simulated return loss of the anteW3

From these results, it can be secan be affected by varying W . By of the C-arms structure, the antennaUHF RFID bands (Europe band, China band, etc.).

Simulations of the surface currdistribution of the antenna at 876 M5a and b, respectively.

(a)

(b)

Fig. 5. Simulated near-field charac(a) Surface current distribution

distribution

0 ,9 5 1 ,0 0

(M H z)

enna with various value of

een that the return loss varying the parameter

a can operate on several North America Band,

rent and magnetic field MHz are shown in Figs

cteristics at 876 MHz : ; (b) Magnetic field

We can see the uniform current distribution along the antenna, which can provide a uniform and sufficient strong magnetic field distribution within the integration zone and can be suitable for UHF near-field RFID reader antenna. We measure the read range of our proposed antenna using near-field UHF RFID Tag. A monostatic system uses the same reader antenna for both transmitting and receiving. The Tag was placed at different distances from the UHF reader antenna, spanning both near and far field regions. We used the Agilent E4438C ESG vector signal generator (50 kHz-6 GHz) as transmitter. The reader uses the antenna to send a radio-frequency signal to activate the Tag, and to read the data from the tag. The data is then transmitted to the computer for processing. The querying signal coming from the reader must have enough power to activate the chip to perform data processing, and transmit back a modulated string over a required reading range. The Tag response is received on HP Agilent 54855A Infiniium oscilloscope. The received Tag response is clearly visible at 868 MHz as shown in Figure 6.

Fig. 6. Portion of the received Tag response at 868 MHz

This reader antenna is suitable for producing strong magnetic field with a uniform field distribution. In near-field UHF RFID, the strength of the magnetic field will decrease rapidly when the distance between the reader and Tag antennas increases. This makes the read range of a near-field Tag quite limited. Measurements show that the proposed UHF near-field RFID reader antenna has a maximum readable range of 7 cm for parallel orientation of the UHF RFID Tag along the positive Z-axis. Fig. 7 shows the measured 2D antenna radiation patterns in the anechoic chamber.

Fig. 7. Measured 2D radiation patterns of the antenna in XZ and YZ plane

IV. CONCLUSION

A compact loop antenna with two C-arms operating at UHF band has been proposed to meet the near-• eld RFID applications. Our proposed antenna has demonstrated the capability of producing a strong magnetic • eld with uniform distribution. The proposed antenna was easily fabricated on a low-cost substrate, small size and suitable to UHF near-field RFID reader applications.

REFERENCES

[1] Finkenzeller: “RFID Handbook, ” 2nd ed., John Wiley &

Sons, 2003. [2] Jia Dong, Xiuping Li,“UHF Near-Field Tags Design Based

on Split Ring Resonator,” Microwave Conference Proceedings (APMC), 2011 Asia-Pacific, 5-8 Dec. 2011, pp. 1794–1797.

[3] M. Dhaouadi, M. Mabrouk, A.Ghazel, “Magnetic Antenna for Near-field UHF RFID Tag,” 18th International Conf. on Microwave, Radar, and Wireless Communications (MIKON), Lithuania, 2010, pp. 1-2.

[4] H. W. Liu, K. H. Wu, “UHF reader loop antenna for near-field RFID Applications,” Electronics Letters, Jan 2010, 46, pp. 10 - 11.

[5] X. Z. Lai, Z. Xie, and X. Cen, “A Compact RFID Reader Antenna for UHF Near-Field and Far-Field Operations,” Inte. J. of Antennas and Propagation, Vol. 2013, Article ID 961042,5 pages, July 2013.

[6] J. Shi, X. Qing, Z. N. Chen and C. K. Goh, “Electrically Large Dual-Loop Antenna for UHF Near-Field RFID Reader,” IEEE Transactions on Antennas and Propagation, March 2013, 61, pp. 1019 – 1025.

[7] Kang, J. J., D. J. Lee, C. C. Chen, J. F.Whitaker, and E. J. Roth-well, “Compact mobile RFID antenna design and analysis using photonic-assisted vector near-field characterization,” Proc. IEEE Int. Conf. RFID, USA , Apr. 2008, pp. 81-88.

Chip Impedance Matching For UHF-Band RFID TAG

Abstract— This paper is concentrated on analyzing the performance of passive Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) tags in which comparison between datasheet impedance and measurement impedance have been used. The novel passive antenna is fabricated by using Polyester (PET) dielectric substrate with permittivity 3.2. The size of antenna is 77 × 14 × 0.05 mm. The HFSS simulator is used for optimizing the proposed antenna. The antenna impedance can be conjugate matched to common UHF chips in market, only by tuning two parameters of the antenna. Keywords: Chip; tag antenna; RF identification (RFID)

I. INTRODUCTION

Radio-Frequency IDentification (RFID) is an automatic non-contact bidirectional identification technology, relying on storing and remotely retrieving data using devices called RFID tags or transponders [1]. RFID UHF bands vary in different countries and include frequencies between 860 MHz and 960 MHz (EPC global standard) [2]. Most popular UHF RFID standards are ISO 18000-6B and recently ratified EPC Gen2.

A passive radio frequency identification transponder is composed of a transponder chip and an antenna in a compact package. The reading range of a RFID system is dependent on the gain of Tag antenna, the power transmission coefficient which is determined by the matching between Tag antenna and microchip, and the power sensitivity. So the Tag antenna which determines the system’s reading range plays a key role in the overall RFID system.

UHF RFID Tags communicate with the reader using backscatter principle. The antenna captures electromagnetic waves from an RFID reader and feeds the power to the transponder chip. The chip responds to the reader by

changing its input impedance between two states 1cZ and 2

cZ, between conjugate match and some other impedance [3]. This change in impedance state modulates the signal backscattered by the RFID Tag antenna and Tag uses this to communicate back to the reader.

However, it is hard to design a tag antenna for passive UHF RFID applications because the attached microchip has a high quality factor that has small resistance and large capacitive reactance at its terminals.

In this paper, for the first time, the effects on RFID Tag antenna parameters due to chip impedance variation between datasheet impedance and measurement impedance are addressed exclusively using HFSS simulator. The antenna Return Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 41.7 dB at 923 MHz with L1= 23 mm and W1=6 mm. The proposed antenna also has the advantages of small size, low cost, and high flexibility.

II. DESIGN EQUIVALENT MODEL

A. RFID Tag A tag consists of a chip and antenna. In typical UHF RFID tags the half-wave length dipole antenna designed resonate on desired frequency is directly connected with IC chip including the circuit for modulation. The equal circuit of a passive UHF RFID tag is shown in Fig. 1.

Figure 1.Equivalent circuit of an RFID Tag

The voltage is induced when the tag is hit by the electromagnetic wave radiated from a reader. The complex

chip impedance cZ is given by cc jXR + and the antenna

impedance aZ is given by aa jXR + . For maximum power

transfer between the tag antenna and the RFID IC, the tag antenna impedance must be the complex conjugate of the RFID IC impedance.

The communication principle of RFID is relatively simple; the reader antenna emits energy which will be received by the tag, and some of the energy is then reflected from the tag and detected by the reader. The variation of the tag’s load (microchip) impedance causes the intended impedance mismatch between the tag antenna and the load.

M. Dhaouadi1, M. Mabrouk1,2, IEEE Member, T.P. Vuong3, IEEE SM, D. Hamzaoui4, A. Ghazel1, IEEE SM 1 GRESCOM Lab, SUPCOM, University of Carthage, Tunisia, [email protected]

2 ISETCOM de Tunis, Cite Technologique des Communications, 2088, Tunisia, [email protected] 3 IMEP-LAHC - UMR 5130, CNRS-INPG-UJF, Minatec-3, rue Parvis Louis Néel- BP 257, 38016 Grenoble Cedex 1, France

4 Laboratory of Electrical Engineering, University of Béjaïa, Algeria

978-88-907018-1-8/13/$31.00 ©2013 IEEE

2013 7th European Conference on Antennas and Propagation (EuCAP)

2947

The varying impedance mismatch results in the variation of the reflected signals. To modulate the signal the tag IC must

present two different impedance states: the first state is 1cZ

matched to the antenna (chip collects power in that state) and

the second state 2cZ is strongly mismatched.

An RFID chip is a nonlinear load whose complex impedance ),( pfZ c in each state varies with the frequency

f and the input power applied to the chip P. The chip circuitry needs certain minimum power to turn on. This threshold and the impedance dependence on the input power are determined by the details of the chip RF front end and the power consumption of the specific chip [4]. The impedance dependence on the frequency is mostly determined by the chip parasitic and packaging effects.

B. Electrical Equivalent Model of UHF RFID Chip

The RFID chip mounted on the tag antenna should be activated with low power at a maximum range. RFID chip input impedances are complex values. Their real part Rc can vary from a few ohms to a few hundred ohms. Their imaginary part Xc are negative due to the capacitive effect of the chip. The electrical equivalent model of the chip input impedance can be modeled either by a series or parallel circuit composed of a resistance and a capacitance. Fig.2 presents the parallel equivalent circuit of the chip input impedance and the series equivalent circuit of the chip input impedance.

Figure 2.Equivalent circuits of the chip input impedance

III. DESIGN PROPOSED ANTENNA

A. RFID chip model from datasheet

The proposed antenna structure is shown in Fig. 3. The antenna is composed of a small rectangular feeding loop and a meandered dipole antenna radiating body, which are T-Match [5]. The antenna parameters are as followings: L1=21mm, L2=21mm, L3=15mm, L4=73mm, L5=3.5mm, L6=2mm, W1=8mm, W2=9.5mm, W3=8.5mm, W4=1mm, W5=0.5mm.

The antenna is simulated with a flexible polyester (PET) substrate (thickness 50H mµ= , relative dielectric constant

3.2rε = , and loss tangenttan 0.003δ = ) with an overall

size of 77 × 14 mm2. The thickness of metal layer ismµ9 .

Those simulation parameters are close to UHF aluminum antenna etching. The operation frequency of the tag is in the UHF band. For the purpose of design calculations, the frequency of 915 MHz has been chosen.

(a)

(b)

Figure 3.Geometry of the proposed broadband tag antenna

(a) Top view (b) Side view

The RFID tag IC selected for this design is an NXP UCODE G2XL [6] which has been widely recognized as a trendy low-cost technique. The IC further needs to be bonded with antenna by conductive glue. The RFID IC impedance is highly capacitive in nature the conjugate match in predominantly inductive. Firstly the proposed antenna structure is optimized for a tag chip with datasheet impedance Ω−= )19322( jZ datasheet

c

at a resonant frequency of 915 MHz. The load antenna impedance should be Ω+= )19322( jZa for conjugate

matching and to transmit the maximum power between the antenna and the microchip. The antenna was designed using electromagnetic simulation tool Ansoft HFSS which allowed us to calculate antenna gain, impedance, and proper matching to the RFID chip. The return loss -48.6 dB is obtained at the frequency 913 MHz is shown in Fig.4.

Figure 4. Simulated Antenna Return Loss

Fig.5 shows the simulated impedance characteristics of the proposed antenna.

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,1))

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m1

m2 m3

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dB(S(1,1))Setup1 : Sw eep1

Name X Y

m1 0.9131 -48.6863

m2 0.6455 -10.1572

m3 0.9636 -9.7005

Name Delta(X) Delta(Y) Slope(Y) InvSlope(Y)

d(m2,m3) 0.3182 0.4567 1.4353 0.6967


2948

Figure 5. Antenna Impedance Against Frequency:

Resistance Component Ra, Reactance Component Xa

In Fig.6 the 2-D and 3-D radiation plots are shown.

Figure 6. 2-D and 3-D far-field radiation plots

B. RFID Chip Impedance Measurement for UHF Tag Design

The impedance of the microchip is not a constant value and it is a function of both frequency and the received power by the chip. The real and imaginary part of the chip input impedance versus power for a fix frequency of 915MHz and versus frequency for fixed power of -2.6 dBm was measured by [7]. Fig.7 shows the real and imaginary part of the commercial NXP GX2L chip input impedance versus power Fig.7.a and versus frequency Fig.7.b.

(a)

(b)

Figure 7. NXP GX2L chip input impedance real and imaginary part in upper and lower state versus input power at 915 MHz (a) and operating frequency

for P=-2.6 dBm (b) [7].

The measured impedance was done for two configurations: for fixed frequency and power sweep

),1( pfZ ic and for fixed power and frequency sweep

)1,( pfZ ic . A SOL calibration procedure is then used to

extract chip impedance values. The measured impedance value of the chip-antenna interface is

Ω−= )79.1476.25( jZ tMeasuremenc

[7].

The RFID Tag antenna should be matched to the measured impedance to obtain best performance. A small rectangular feeding loop is used to adjust the power transmission coefficient between the tag antenna and the microchip (i.e., to implement the impedance conjugate-matching between the tag antenna and the microchip). Fig.8 and 9 show the return loss and impedance of RFID tag antenna with variation of the parameter W1. I can be seen from fig.8 that the impedance conjugate-matching is optimized while W1 is 6 mm. The return loss -41.7 dB is obtained at the frequency 923 MHz.

Figure 8. Return Loss of the tag antenna for various W1

(a) Resistance Component Ra

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m1 0.9131 22.1185

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max(dB(GainTotal))Setup1 : LastAdaptiveFreq='0.915GHz'

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m1 0.9232 -41.7075

m2 0.9131 -30.5071

m3 0.8980 -24.7801

m4 0.8727 -23.2779

m5 0.8374 -22.4991

m6 0.9131 -19.5135

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m1 0.9232 25.0321


2949

(b) Reactance Component Xa

Figure 9. Input impedance of the tag antenna for various W1

From the result, we can see that by decreasing the size of the ring, the impedance (both real and imaginary parts) of the antenna will decrease too. The impedance characteristics show that the resistance and reactance of the antenna input impedance vary around the conjugate value of the microchip input measurement. This antenna can be easily tuned by trimming to provide a better match for the chip capacitive impedance. Length of L1 can be varied to obtain optimum resistance and reactance matching. Antenna reactance and resistance can be controlled by trimming is shown in Fig.10.

Figure 10. Input impedance of the tag antenna for various L1

Return Loss of the tag antenna is significantly affected by trimming as it is shown in Fig.11.

Figure 11. Return Loss of the tag antenna for various L1

It can be seen that the good impedance can be achieved (25.03+j145.4 Ω at 923 MHz) with L1= 23 mm and W1=6 mm.

IV. CONCLUSION

A novel antenna for passive UHF RFID tag applications is presented. Due to the diversity of fabrication technology and antenna loadings, there is a divergence between the datasheet impedance and measurement impedance. The impedance of the tag antenna can be simply adjusted by changing L1 and W1. The antenna has good characteristics low cost, small size, and high flexibility. The reported results provide useful insight and design rules for UHF RFID tag development. In the future, the antenna reduction and measurement will be investigated.

REFERENCES [1] K. Finkenzeller, “RFID Handbook,” 2nd ed., John Wiley & Sons,

2003.

[2] Technical report, “860MHz–960MHz Class I Radio Frequency Identification Tag Radio Frequency& Logical Communication Interface Specification Recommended Standard”, Version 1.0.0, Auto-ID Center, November 14, 2002.

[3] K. V. S. Rao, P. V. Nikitin, S.F. Lam, “Antenna design for UHF RFID tags: a review and a practical application”, IEEE Transactions on Antenna and Propagation, vol.53,no.12, Dec.2005.

[4] G. De Vita and G. Iannaccone, “Design criteria for the RF section of

UHF and microwave passive RFID transponders”, IEEE Transactions on Microwave Theory and Techniques, vol. 53, no. 9, Sept. 2005, pp. 2978-2990

[5] G. Marrocco,“The art of UHF RFID antenna design : impedance-matching and size-reduction techniques”, IEEE Antennas and Propagation Magazine, Vo.50, N.1, Jan. 2008.

[6] UCODE G2XM and UCODE G2XL (TSOOP8 Package Specification) from December 2007, http://www.nxp.com/ .

[7] Daiki, Chaabane, Perret,Tedjini, Aguili, “RFID Chip Impedance Measurement for UHF Tag Design”, Progress In Electromagnetics Research Symposium (PIER’11), Marrakesh, Morocco, March 20-23, 2011.

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m1 0.9232 145.4125

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m1 0.9384 26.0494

m2 0.9384 148.7315

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m1 0.9384 -49.5482

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2950

Electromagnetic analysis of UHF Near-field RFID Tag Antenna

M. Dhaouadi1, M. Mabrouk1, IEEE Member, A. Ghazel1, IEEE Senior Member and

S. Tedjini2, IEEE Senior Member

1CIRTACOM, SUPCOM-ISETCOM de Tunis, University of Carthage, Cité Technologique des Communications, 2088, Tunisia

2ORSYS, LCIS, ESISAR-INPG, 50 rue de Laffemas, BP 54, 26902, Valence Cedex 9, France

[email protected] [email protected]

Abstract

In this paper, the performance of Near-Field UHF RFID systems is investigated by means of electromagnetic

analyses. A novel antenna is presented for ultra high frequency (UHF) near-field radio frequency identification (RFID) applications. The reactance component of tag antenna considered chip impedance (-193j) is conjugated and matched for maximum power transmission. The antenna is fabricated by using Polyester (PET) dielectric substrate with permittivity 3.2. The size of antenna is 38 × 18 × 0.5 mm. The HFSS simulator is used for optimizing the proposed antenna. The antenna Return Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 31.4 dB at 900 MHz.

1. Introduction

The RFID (Radio Frequency Identification) is a non-contact method for data transfer to object identification [1]. Two major characteristics that distinguish different types of RFID systems are the power source of the tag and the frequency of operation [2]. RFID can be categorized into two types: an active RFID capable of transmitting an electromagnetic wave containing information of the RFID, and a passive RFID which drives utilizing power of an electromagnetic wave externally received. A strictly passive RFID system uses the energy from the field radiated by the reader to completely power the tags. The tag then uses this energy to identify itself and communicate with the reader. The basic near field UHF RFID concept is to make UHF RFID system work at short distances and on different objects as reliably as LF/HF RFID [3]. Near-field UHF technology is capable of transmitting in the near-field, similar to HF, but is faster and works well around metals and liquids [4]. The aim of this work is to investigate the electromagnetic characteristics of UHF near field RFID Tag Antenna.

2.Near-field UHF RFID Tag

Near field RFID are based on inductive coupling between the reader and the Tag. UHF near-field RFID is increasingly popular for item-level tagging because the tag can be detected more consistently on various objects such as bottles of water, CD/DVD, and small items [5]. Since the major part of reactive energy is stored in the magnetic field, the system of inductive coupling is preferred for the communication between the antenna of reader and the antenna of Tag. Most of the near field UHF RFID Tags antennas are rectangular or circular loops, as these electrically small loop antennas are able to produce a strong and uniform magnetic field in the region around the antenna. Finally, to have a good magnetic coupling in near field UHF RFID Tag antenna, it is necessary to use T-match configuration with a circular or rectangular for tags antennas [6].

3. ANTENNA DESIGN

Fig. 1 shows the proposed tag antenna structure. The antenna is fabricated with a flexible polyester (PET) substrate (thickness m50H µ= , relative dielectric constant 3.2ε r = , and loss tangent 0.003tanδ = ) with an

overall size of 38 × 18 mm2. The detailed dimensions of the antenna prototype are: L1 = 13.9 mm, L2 = 6.95 mm,

978-1-4244-6051-9/11/$26.00 ©2011 IEEE

W1 = 1 mm, W2=1.08 mm and W3 = 2 mm. The operation frequency of the tag is in the UHF band. For the purpose of design calculations, the frequency of 900 MHz has been chosen.

Figure 1. Antenna structure (a) Top view (b) Side view

Integrated chip ASIC Philips (NXP UCODE) enclosed in TSSOP8 body was used for the tag [7]. For

maximum power transfer between the tag antenna and the RFID IC, the tag antenna impedance must be the complex conjugate of the RFID IC impedance. The RFID IC impedance is highly capacitive in nature the conjugate match in predominantly inductive. In this paper the antenna is designed for a tag chip with j193)Ω(22Zc −= at a resonant

frequency of 900 MHz. The load antenna impedance should be j193)Ω(22Za += for conjugate matching and to

transmit the maximum power between the antenna and the microchip.

4. Results

4.1 Antenna Performance The antenna was designed using electromagnetic simulation tool Ansoft HFSS which allowed us to calculate

antenna gain, impedance, and proper matching to the RFID chip. The return loss -31.4 dB is obtained at the frequency 900 MHz is shown in Fig.2.

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Fig.3 shows the predicted VSWR performance of the antenna vs frequency (at 900 MHz).

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m2 0.9000 182.8947

Figure 3. Antenna impedance against frequency: Resistance component Ra, Reactance component Xa

The Voltage Standing Wave Ratio (VSWR) of antenna is another characteristic parameter used to measure

the impedance matching of an antenna to its connected load. It is defined as the ratio of the reflected voltage over the incident voltage. Fig.4 shows that for a VSWR of 0.46dB.

0.50 0.75 1.00 1.25 1.50Freq [GHz]

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Figure 4. Antenna VSWR vs. frequency

4.2 Field Analysis of Tag antenna

In order to analyze the performance in the near zone, the electric field distribution is simulated in horizontal plane. Electric fields are created by differences in voltage: the higher the voltage, the stronger will be the resultant field. Fig. 5 illustrates electric field distribution in the near-field RFID Tag antenna shown in Fig. 1. The electric fields are strongest close to their origin (chip) and rapidly decrease at greater distances from the chip NXP (source).

Figure 5. Electric field plot of the UHF near field RFID Tag Antenna

Fig. 6 shows the simulated magnetic field distribution in the near-field RFID Tag antenna.

Figure 6. Magnetic field plot of the UHF near field RFID Tag Antenna

The current on a side of the rectangular feed loop is not same magnitude as that on other side of the radiating body but it is reduced progressively. The current fluctuation generates a variation of magnetic field. Then the strength of the magnetic field decreases with the diminution of the current. The reduction in the magnetic field produces a distribution of this field which is not uniform for near-field RFID applications.

Rectangular feed loop Radiating body

4.3 Placing antenna Tag RFID in metal environment

It is expected that the thin metal foil will reduce the performance of the RFID tag [8]. Metal introduces difficulties for antennas in systems using radio communication in the far field as well as for antennas in inductively coupled systems working in the near field. Fig.7 illustrates the influence of a metal plate on the radiation pattern of antenna Tag RFID.

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Figure 8 . Simulated directivity pattern of the tag antenna structure located in metallic environments

A magnetic field cannot penetrate metal or other magnetically conductive materials. The course of the lines

of electric flux is changed and has therefore a considerable influence on the radiation pattern.

5. Conclusion

In this paper, the performance of Near-Field UHF RFID systems is investigated by means of electromagnetic analyses. We presented a novel planar RFID Tag antenna for near-zone UHF communication. Besides the space limitation, we verified that the thin metal foil will reduce the performance of the RFID tag.

6. References 1. R.Schneiderman, “RFID Tags Locate Growing Wireless Markets”, Microwaves & RF Magazine, Feb.1994. 2. K. Finkenzeller, “RFID Handbook: Fundamentals and Applications in Contactless Smart Cards and Identification”, John Wiley and Sons, England, 2003. 3. Nikitin, P.V. Rao, K.V.S. Lazar, S. “ An Overview of Near Field UHF RFID” , IEEE International Conference on RFID, 2007.

4. Claire Swedberg, “A Shift to UHF Near-Field Predicted for Pharma”, RFID Journal, 2005, www.rfidjournal.com/article/.../rfidjournal-article2694.PDF. 5. A. Shameli, A. Safarian, A. Rofougaran, J. Castaneda, and F. De Flaviis, "A UHF near field RFID system with fully integrated transponder," IEEE Trans. Microw. Theory Tech., vol. 56, pp.1267-1277, May 2007. 6. M.Dhaouadi, M.Mabrouk, A.Ghazel, “Magnetic antenna for near-field UHF RFID tag”,18 th International conference on Microwave, Radar and Wireless Communications MIKON-2010, June 2010. 7. UCODE G2XM and UCODE G2XL (TSOOP8 Package Specification) from December 2007, http://www.nxp.com/ .

8. Byunggil Yu, Sung-Joo Kim, Byungwoon Jung, Harackiewicz F.J, Myun-Joo Park, Byungje Lee, “Balanced RFID Tag Antenna Mountable on Metallic Plates”, Antennas and Propagation Society International Symposium, IEEE, July 2006.

Influence of Magnetic Near-Field on UHF RFID Tag

Abstract — Method for improving the UHF-RFID Tag

antenna performances in near field zone is proposed. The design of studied Tag antenna is based on feeding T-match structure. The impedance matching between passive UHF-RFID Tag antenna and integrated chip is obtained using two stubs. The HFSS simulator is used for optimizing the proposed antenna. The antenna Return Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 29.0 dB at 868 MHz and 35.0 dB at 931 MHz. The impedance matching principle was particularly consisting to have the imaginary part of antenna impedance to be the opposite of the imaginary part of integrated chip impedance (-193j) which was effectively obtained by simulation.

Keywords: UHF-RFID Tag; near-field; magnetic coupling

I. INTRODUCTION

Radio-Frequency IDentification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders [1]. First functional passive UHF RFID systems with a range of several meters appeared in early 1970’s [2]. Since then, RFID has experienced a tremendous growth. RFID UHF bands vary in different countries and include frequencies between 860 MHz and 960 MHz (EPC global standard) [3]. Most popular UHF RFID standards are ISO 18000-6B and recently ratified EPC Gen2.

UHF RFID Tags communicate with the reader using backscatter principle. The chip in the tag harvests the RF power transmitted by the reader in order to provide power supply for the chip. The chip uses this power to switch between two impedance states [4, 5]. This change in impedance state modulates the signal backscattered by the RFID Tag antenna and Tag uses this to communicate back to the reader.

Near field RFID are based on inductive coupling between the reader and the Tag. It appears today that one of the limitations of Tags UHF is that they do not function at short distances (near field). As a result, this greatly spurs the investigation into antennas for UHF near-field applications.

In this paper, we concentrate on the performances improving of UHF RFID Tag antenna in near field.

II. PHYSICAL CONSIDERATIONS IN NEAR FIELD

Most of the RFID systems are based on the principles of inductive coupling in electromagnetic theory. The space surrounding an antenna is usually divided into three regions: reactive near-field, radiating near-field and far field, as illustrated in Figure 1. Reactive near-field is the region immediately surrounding the antenna wherein the reactive field predominates. Radiating near-field is the region of the field of an antenna between the reactive near-field region and the far field region wherein radiation field predominates (while there still coexists reactive field).

In far-field region, the field strength is attenuated as r/1 along the distance from the transmit antenna. However, the strength of near-

field is attenuated as 3/1 r . The approximate boundary between the far-field (Fraunhofer) and the near-field (Fresnel) region is generally given as λ/2 2Dr = whereD is the maximum antenna dimension and λ is the wavelength as described in detail in [6].

III. NEAR-FIELD UHF RFID SYSTEMS

The magnetic field induction between the reader and Tag enables communication. Near field RFID is commonly operated in low and medium frequency bands. UHF near-field RFID technology receives a lot of attention owing to the promising item-level applications for pharmaceutical [7-8]. The basic near field UHF RFID concept is to make UHF RFID system work at short distances and on different objects as reliably as LF/HF RFID [9-10].Near-field UHF technology is capable of transmitting in the near-field, similar to HF, but is faster and works well around metals and liquids [8]. Since the major part of reactive energy is stored in the magnetic field, the system of inductive coupling is preferred for the communication between the antenna of reader and the antenna of Tag. The near magnetic field around the multi-loop antenna is higher than a general single loop tag. The multi-loop tag conserves the near magnetic field for an induced current more than a single loop tag as to run the microchip very well [11]. Currently, near-field UHF RFID receives a lot of attention as a possible solution for item level tagging in various applications.

Most of the near field UHF RFID Tags antennas are rectangular or circular loops, as these electrically small loop antennas are able to produce a strong and uniform magnetic field in the region around the antenna.

Conventional loop antennas have been used as reader/tag antennas in HF/UHF RFID systems. The segmented loop antenna has demonstrated the capability of producing a strong magnetic field with a relatively uniform field distribution [12].

The UHF performances of the tag and reader antennas in near-field can be used for RFID smart shelf for agricultural products management [13]. Reader and tag antennas embedded in the shelf

(1)M. Dhaouadi, (1)M. Mabrouk, IEEE Member, (1)A. Ghazel, IEEE Senior Member and

(2)S. Tedjini, IEEE Senior Member (1)CIRTACOM, SUPCOM-ISETCOM de Tunis, University of 7th November at Carthage,

Cité Technologique des Communications, 2088, Tunisia Tél. : +216-71-857000, Fax : +216-71-8575555

(2)ORSYS, LCIS, ESISAR-INPG, 50 rue de Laffemas, BP 54, 26902, Valence Cedex 9, France Tél. : +33-04-75 75 94 00, Fax : +33-04-75 75 94 50

[email protected]

FIGURE 1 – REGION OF NEAR-FIELD AND FAR-FIELD

HF

Radiating

Near Field (50cm) Far Field

UHF

Reactive

offer strong and uniform near-field distribution over a specified range without dead zones. They also have design flexibility to easily change the size and shape of the antenna depending on shelf configuration.

Finally, to have a good magnetic coupling in near field UHF RFID Tag antenna, it is necessary to use T-match configuration [14] with a circular or rectangular for tags antennas. The electromagnetic waves can be dispersed by the antenna with inductively coupled feed because this method of feed generates a discontinuity of magnetic field and electric between the loop and the radiating body [15].

IV. TAG ANTENNA ANALYSIS

A microstrip patch antenna is constructed by sandwiching a layer of dielectric between two conducting planes, the ground and the antenna. The structure of the proposed antenna is presented in Figure 2.

The tag antenna was small meander dipole on a FR4 substrate (thickness h=0.8mm, relative dielectric constant 4.4=rε , and loss

tangent 02.0tan =δ ). The dimensions of the antenna prototype are Wsub=94mm, Lsub=76.7mm, W=84mm, L=25mm, L1=37mm, L2=10.3, L3=7.5mm, L4=7mm, L5=3mm, W1=39mm, W2=43mm, W3=19.5mm, as well as the details of the antenna are illustrated in Fig. 4. Integrated chip ASIC Philips (NXP UCODE) enclosed in TSSOP8 body was used for the tag [16]. For maximum power transfer between the tag antenna and the RFID IC, the tag antenna impedance must be the complex conjugate of the RFID IC impedance. The RFID IC impedance is highly capacitive in nature the conjugate match in predominantly inductive. In this paper the antenna is designed for a tag chip with Ω−= )19322( jZc

at a resonant frequency of 868 MHz. The

load antenna impedance should be Ω+= )19322( jZa for conjugate

matching and to transmit the maximum power between the antenna and the microchip. The tag’s design is constructed in such a way that there is no need for extra elements in order to match the antenna input impedance with the chip impedance.

V. RESULTS

5.1 Antenna Performance

The Tag antenna structure is analyzed by the HFSS software and its performances are depicted.

Figures 3 and 4 show the Return Loss and impedance of antenna versus frequency.

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In Figure 5 the 2-D and 3-D radiation plots are shown.

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FIGURE 2 – TAG ANTENNA STRUCTURE WITH T-MATCH CONFIGURATION

FIGURE 3 – SIMULATED ANTENNA RETURN LOSS

FIGURE 4 – ANTENNA IMPEDANCE AGAINST FREQUENCY:

RESISTANCE COMPONENT aR , REACTANCE COMPONENTaX

FIGURE 5 – 3-D AND 2-D FAR-FIELD RADIATION PLOTS

5.2 Field Analysis of Tags antennas The current on a side of the rectangular feed loop (A) is not same

magnitude as that on other side of the radiating body but it is reduced progressively. The current fluctuation generates a variation of magnetic field. Then the strength of the magnetic field decreases with the diminution of the current. The reduction in the magnetic field produces a distribution of this field which is not uniform for near-field RFID applications.

Figure 6 shows the difference of the distribution of magnetic field in near-field between RFID tag antennas using an inductively coupled feed and RFID tag antennas using T-match configuration. Our design and simulation results confirm the tag antennas using T-match configuration conserves the near magnetic field potentialities more than a tag antennas using an inductively coupled feed.

VI. CONCLUSIONS

The performance of system near-field to RFID is improved with the use of RFID tag antennas using T-match configuration. From the simulation results, we confirmed that antennas using T-match

configuration conserves the near magnetic field for an induced current more than an antenna with inductively coupled feed. Similar to near-field UHF RFID tag, the UHF near-field RFID reader antenna must be to study to increase the magnetic field between the two antennas.

REFERENCES

[1] K. Finkenzeller, “RFID Handbook,” 2nd ed., John Wiley & Sons, 2003

[2] S.Tedjini, T. Vuong, “Radio Frequency Identification, a technology for the future,” URSI (Union Radio-Scientifique Internationale), in Chicago, USA, August 2008.


[4] Lindsey, J. F., “Radar Cross-Section Effects Relating to a Horn Antenna”, IEEE Transactions on Antennas and Propagation, vol. 37, no. 2, pp. 257-260, February 1989.

[5] P. V. Nikitin, K. V. S. Rao, “Measurement of backscattering from RFID tags”, Proceedings of Antennas Measurement Techniques Association Symposium, Newport, RI, October 2005.

[6] C. A. Balanis, “Antenna Theory, Analysis, and Design”, New York, 3rd ed., J. Wiley.

[7] “Item-level visibility in the pharmaceutical supply chain : a comparison of HF and UHF RFID technologies”, http://www.tagsysrfid.com/modules/tagsys/upload/news/TAGSYSTI- Philips-White-Paper.pdf.

[8] Claire Swedberg, “A Shift to UHF Near-Field Predicted for Pharma”, RFID Journal,2005, www.rfidjournal.com/article/.../rfidjournal-article2694.PDF.

[9] Nikitin, P.V. Rao, K.V.S. Lazar, S. “ An Overview of Near Field UHF RFID” , IEEE International Conference on RFID 2007.

[10] P. Harrop, “Near field UHF vs. HF for item level tagging”,IDTechEx article, available at http://www.eurotag.org/?Articles_and_Publication.

[11] J. Choo, J. Ryoo, I. Park, J. Hong, K. Park, J. Lee, “A Novel Multi-loop Tag for Near Field Communication in UHF Band”, Proceedings of Asia-Pacific Microwave Conference, December 2007.

[12] Qing, X., Goh, C.K., and Chen, Z.-N., “Segmented loop antenna for UHF near-field RFID applications”, Electronics Letters, 2009.

[13] Wonkyu Choi Jeong-Seok Kim Ji-Hoon Bae Gilyoung Choi Jong-Suk Chae, “Near-field antenna for RFID smart shelf in UHF” APSURSI '09, June 2009.

[14] G. Marrocco,“The art of UHF RFID antenna design : impedance-matching and size-reduction techniques”, IEEE Antennas and Propagation Magazine, Vo.50, N.1, Jan. 2008.

[15] H. H. W. Son and C.S. Tyo, “Design of RFID tag antennas using an

inductively coupled feed”, Electronics Letters, 41,18, September 2005,

pp. 994-996.

[16] UCODE G2XM and UCODE G2XL (TSOOP8 Package Specification)

from December 2007, http://www.nxp.com/ .

(B) MAGNETIC FIELD PLOT OF THE ANTENNA USING T-MATCH

CONFIGURATION

(A) MAGNETIC FIELD PLOT OF THE ANTENNA WITH INDUCTIVELY

COUPLED FEED

FIGURE 6 – SIMULATED NEAR-FIELD PLOTS OF UHF

RFID TAG ANTENNA

International Conference on Information Processing and Wireless Systems

March 16, 17 and 18 2012, Tej MARHABA Sousse Tunisia

2

Planning

Friday March 16, 2012 Saturday March 17, 2012 Sunday March 18, 2012

8:00 - 8:30

Registration

Registration Registration

8:30 - 9:00 Plenary Session 2 Plenary Session 4

9:00 - 9:30

9:30 - 10:00 Oral Sessions Room A : Papers 1, 2 and 31

Room B : Papers 25, 41 and 48

Oral Sessions Room A : Papers 9, 21 and 29

Room B : Papers 13, 23 and 43 10:00 - 10:30

10:30 - 11:00 Coffee Break Coffee Break

11:00 - 11:30 Oral Sessions Room A : Papers 44, 53 and 56 Room B : Papers 26, 52 and 55

Oral Sessions Room A : Papers 4 and 5

Room B : Papers 58, 59 and 61 11:30 - 12:00

12:00 - 12:30 Poster Sessions 2 Papers 11, 32, 60, 64 and 65

Poster Sessions 3 Papers 8, 22, 33, 42 and 49 12:30 - 13:00

13:00 - 13:30

Lunch Lunch Closing and Lunch 13:30 - 14:00

14:00 - 14:30

14:30 - 15:00

15:00 - 15:30 Allocution of the Minister of Higher Education and Scientific Research (15’)

Allocution on The Minister of Communication Technologies (15’)

& Plenary Session 1 (60’)

Plenary Session 3

15:30 - 16:00


16:30 - 17:00 Coffee Break


Coffee Break



18:00 - 18:30 Poster Sessions 1 Papers 3, 6, 20, 35, 39 and 47

18:30 - 19:00

20:00 GALA DINNER

3

Oral Session

Session 1A-1: MIMO OFDM Friday PM, March 16 , 2012, Room A

Chair: Ammar BOUALLEGUE ; Co-chair: Hichem BESBES

ID Title Authors

18 Joint ML and MAP Channel Estimation for MIMO-OFDM System Under High Mobility

Conditions

Zaier Aida and Bouallegue Ridha

Abstract :

In this paper, we propose an improvement of the Maximum Likelihood estimator in a MIMO OFDM (Multi Input Multi Output - Orthogonal

Frequency Division Multiplexing) system. As known, the combination between the two techniques allows spectral efficiency and increased

throughput.

Thus, this work focuses on channel estimation in a MIMO context based on a rigid estimator which is the maximum likelihood one and which has

been used as a tracker of the channel in others works. Then, we will compare the performance of this estimator with the Maximum A Posteriori

one (MAP) since it demonstrates too its effectiveness.

The performance of the estimator will be expressed in term of bit error rate BER versus the signal to noise ratio SNR. For a (2,2) MIMO system,

our simulations results shown a great enhancement comparing to related works as for different schemes of the MIMO system .

62 PAPR reduction for SFBC MIMO-OFDM systems Laabidi Mounira, Zayani Rafik and

Boualleugue Ridha

Abstract : Multiple input multiple output techniques, combined with orthogonal frequency division multiplexing (MIMO-OFDM), provide a promising approach for wireless systems. However, a serious drawback of the OFDM system consists in the high peak-to-average power ratio (PAPR) which may severely affect the power efficiency of RF power amplifiers. In this paper, we propose two methods to reduce the PAPR of SFBC MIMO-OFDM signals based on the rotation and inversion across antenna. To secure the efficiency of these methods, we compare them with Polyphase Interleaving and Inversion method.

63 Mimetic Crossover Neural Network Predistortion for the compensation of memory crosstalk

and HPA nonlinearity effects on MIMO-OFDM systems

Hanen Bouhadda, Rafik Zayani, Ridha

Bouallegue and Daniel Roviras

Abstract : In this paper, we investigate the joint effects of memory crosstalk and HPA nonlinearity in multicarrier OFDM-MIMO systems by proposing a new structure of Neural Network Predistortion which consists to eliminate those effects. Then, we will compare those results with those already obtained in [1].

4

The algorithm used to train the neural network is the Levenberg-Marquardt one (LM), which has proven in [2] to exhibit a very good performance with lower computation complexity and faster convergence than other algorithms used in literature. The present results where observed for the Alamouti STBC MIMO-OFDM system in terms of Bit Error Rate (BER) in Rayleigh fading channel.

5

Session 1B-1: Antennas Friday PM, March 16 , 2012, Room B

Chair: Taoufik AGUILI; Co-chair: Henri BAUDRAND

12 Interaction between Five-Layered Human Head Model and a Half- Wave Dipole Antenna Hafawa Messaoudi and Taoufik Aguili

Abstract : The interaction between a five-layered human head model and a half-wave dipole antenna is analyzed in this paper. It is well known, that some of the radio waves emitted by a mobile phone handset are absorbed by the human head. The specific absorption rate (SAR) is a defined rate to evaluate the power absorbed by biological tissue. The results show that the SAR distribution is influenced by various parameters such as antenna position relative to the human head, polarization and distance, the shape and geometry of the head. Whether or not those parameters affect significantly antenna performances specially its radiation pattern. The antenna radiation pattern and other characteristic are significantly altered by the presence of the human head.

17 Synthesis and implementation of Phased Circular Antenna Arrays Using Taguchi Method Nadhem Nemri, Amor Smida, Ridha

Ghayoula, Hichem Trabelsi and Ali

Gharsallah

Abstract : This paper is aimed at assessing the effectiveness of the phase-only control strategy based on a customized Taguchi method when applied to Uniform Circular Arrays (UCA). The objective of this paper consists to contribute the main lobe optimization of the smart antenna using Taguchi's method. We used the cited method in order to determine phase's weights for each element of the circular antenna array in order to steer the principal lobe from -65° to 65° covering all angular space. After that, we made an electronic platform using the microcontroller STM8S in order to implement an intelligent system. The architecture of this work had used a digital phase shifters, a demodulator AD8347, a modulator AD8349, an array antenna, cards STM8S-Discovery.

50 A Smart Antenna System based on Planar Array Antenna Faten Ben Ghenaya and Ridha

Ghayoula

Abstract : In this paper, a novel design of smart antenna system based on planar (ring) array antenna beamforming is proposed. The goal of the design is to construct smart antenna beamforming systems with uniformly spaced radiating elements and with equal amplitude and phase excitation have long been used for the purpose of obtaining good omnidirectional patterns in the plane of the array. However, the mutual coupling effects will be introduced. To verify the performances of the proposed technique, a 4-elements array has been realized and tested for various types of beam configurations.

http://www.easychair.org/utils/wild.cgi?url=http://www.fst.rnu.tn



6

Session 2A-1: LTE Saturday AM, March 17 , 2012, Room A

Chair: Neji YOUSSEF ; Co-chair: Adel GHAZEL

1 Performance Evaluation of a Hybrid LS-LMMSE Channel Estimation Technique for

different LTE Downlink Systems

Abdelhakim Khlifi and Ridha

Bouallegue

Abstract : In this paper, we propose to study the performance of the hybrid LS-LMMSE channel estimation technique for different LTE Downlink systems. LTE Downlink system is based on a MIMO-OFDMA technology. In OFDM systems, in order to mitigate both inter-carrier interference (ICI) and inter-symbol interference (ISI) caused by the multi-path propagation, a cyclic prefix inserted at the beginning of each transmitted OFDM. The inserted cyclic prefix length is defined to be equal to or longer than the channel length. However, and due to some unforeseen channel behavior, the cyclic prefix can be shorter than the channel length. In previous works, we have studied the performance of Least Square (LS) and Linear Minimum Mean Square (LMMSE) estimators under the effect of the channel length, we have concluded that in the case where the cyclic is equal to or longer than the channel length, LMMSE performs better than LS estimator. In the other case, LMMSE still performs better than LS estimator but this time for only low SNR values. For high SNR values, LS estimator shows better performance. Therefore, we have further proposed a hybrid LS-LMMSE channel estimator robust to the channel length effect. LTE provides a scalable bandwidth from 1.25 MHz to 20 MHz. Each LTE downlink system has its own technical specifications in terms of frequency sampling, FFT size,… In this paper, we will study the performance of the proposed hybrid LS-LMMSE channel estimator for different LTE Downlink systems. MATLAB Monte –Carlo simulations are used to evaluate the performance of this estimator in terms of Mean Square Error (MSE) and Bit Error Rate (BER) for 2x2 LTE Downlink systems under the channel length effect.

2 Performance of Channel Estimation Techniques for LTE Downlink Systems under the

Channel Length Effect


Bouallegue

Abstract : In this paper, we propose to study the impact of the channel length of the performance of channel estimation techniques for LTE Downlink systems. LTE Downlink system is a multiuser system based on a MIMO-OFDMA technology. Usually, in OFDM systems, before transmitting an OFDM symbol, a guard interval called cyclic prefix (CP) is inserted at the beginning of each transmitted OFDM symbol in order to mitigate both inter-carrier interference (ICI) and inter-symbol interference(ISI). Usually, the inserted cyclic prefix is chosen equal to or longer than the channel length. However, because of some unforeseen channel behavior,the cyclic prefix can be shorter. In this paper, we interest to study the performance of channel estimation techniques in the two cases.Simulations results show that in the case where the cyclic prefix is equal to or longer than the channel length, LMMSE and SVD estimators perform better than LSE but at the cost of computational complexity. LSE performs better than SVD estimator only for very high SNR values.In the other case, LMMSE and SVD estimators look to perform better than LS but only for low SNR values. In the other hand, LS looks the better for LTE Downlink systems for high SNR values. MATLAB Monte–Carlo simulations are used to evaluate the performance of LS, LMMSE and SVD in terms of Mean Square Error (MSE) and Bit Error Rate (BER) for 2x2 LTE

7

Downlink systems under the channel length effect.

31 A Study of Channel Estimation for 3GPP’s SPATIAL CHANNEL MODEL Extended in

Downlink LTE Systems

Samia Dardouri and Ridha Bouallague

Abstract : In this paper, we study the channel estimation algorithms for the downlink LTE systems of 3GPP. By using computer simulation, the pilot signal assisted channel estimation algorithms based on least square (LS), linear minimum mean square error (LMMSE) criteria and SVD-LMMSE channel estimation, together with channel interpolation based on linear interpolation. The channel model is chosen as a typical urban scenario modeled by Spatial Channel Model Extended (SCME), which is implemented with the LTE downlink structure in this paper. The performance is measured using the mean square error (MSE) between LMMSE estimator with optimal rank reduction by singular value decomposition (SVD) can improve the estimation performance effectively. All channel estimation algorithms are simulated. The simulation conclusion is that the new channel estimations are more efficient. We conclude that the channel frequency responses of pilot tones are estimated by using SVD-LMMSE estimator, and the channel frequency responses of data tones are interpolated by linear based interpolation method is appropriate for the downlink of 3GPP LTE systems.

8

Session 1B-1: RCF, Propagation Environment & Neural Network Saturday AM, March 17, 2012, Room B

Chair: Kosai RAOOF; Co-chair: Mahmoud AMMAR

25 Model Checking Techniques for Verification of an Encryption Scheme for Wireless Sensor

Networks

Zohra Sbaï and Mohamed Escheikh

Abstract : In this paper, we deal with the formal verification of an encryption scheme for Wireless Sensor Networks (WSNs). Especially, we present our first results on building a framework dedicated to modelling and verification of WSNs aspects. To achieve our goal, we propose to specify WSNs models written in Petri nets using Promela constructs in order to verify correctness properties of them using SPIN Model checker. We first specify in Promela a Petri net description of an encryption scheme for WSNs that describes its behavior. Then, correctness properties that expressrequirements on the system’s behavior are formulated in Linear Temporal Logic (LTL). Finally, SPIN model checker is used to check if a specific correctness property holds for the model, and, if not, to provide a counterexample: a computation that does not satisfy this property. This counterexample will help to detect the source of the eventual problem and to correct it.

41 Simulation of Polarization Strategies of Multiple Antennas System over Rich Scattering

Environment Using the Von Mises Distribution

Maha Ben Zid

Abstract : The aim of this paper is to present a comparative study of polarization strategies of multiple antennas systems over a realistic propagation environnement with rich scatterers. We investigate the von Mises distribution for the analysis of the capacity of the communication systems with different polarizations. We demonstrate in this paper that the polarization strategy that performs better still depends on the distribution characterizing the scattering phenomena within the propagation environment.

48 Performance Analysis of Neural Network Compensator for MIMO-STBC System in Presence

of HPA Nonlinearity and Channel Estimation Error

Oussama Ben Hadj Belkacem,

Ammari Mohammed Lassaad, Rafik

Zayani and Ridha Bouallegue

Abstract :

In order to provide high data rate over wireless channels and improve the system capacity, Multiple-Input Multiple-Output (MIMO) wireless

communication systems exploit spatial diversity by using multiple transmit and receive antennas. Maximal Ratio Combining (MRC) detection is a

simple and effective combiner technique for retrieving multiple transmitted data streams at the receiver. However the detection requires

knowledge of the Channel State Information (CSI) and in practice accurate CSI may not be available. Moreover, to achieve high date rate and

fulfill the power, MIMO systems are equipped with High Power Amplifiers (HPAs).

However, HPAs cause nonlinear distortions and affect the receiver’s performance. Since a few decades, Neural Networks (NN) have shown

excellent performances in solving complex problems (like classification, recognition, approximation). In this paper, we investigate the effect of

9

channel estimation error on the performance of MIMO Space-Time Block Coding (STBC) receiver in the presence of nonlinear HPAs and NN.

By modeling the estimation error as independent complex Gaussian random variables, we assess the impact of HPA nonlinearity and NN on the

SNR derivation and the Symbol Error Rate (SER) in uncorrelated Rayleigh fading channels. Computer simulation results confirm the accuracy

and validity of our proposed analytical approach.

10

Session 2A-2: Wave Structures Saturday AM, March 17, 2012, Room A

Chair: Ali GHARSALLAH; Co-chair: Jamel BELHAJ TAHAR

44 Applying Renormalization Group to Multi-modal Surface Impedance Operator for

Diffraction Analysis

Taha Ben Salah, Chiraz Aguili and

Taoufik Aguili

Abstract :

In this paper we discuss a new accurate method for analyzing diffraction of a fractal shaped structure ad infinite iteration using a combination of

the Renormalization Group Theory and the Multi-modal surface impedance Operator. This new approach helps calculating input impedance of

the structure where no other method pretends being able to provide a concrete characterization of such infinitely complex multi-scale structure.

53 New Tunable Phase Shifter Using Loaded Stepped Impedance Structure Mohamed Ould Elhassen, Mohamed

Mabrouk, Philippe Benech and Adel

Ghazel

Abstract :

This paper presents a stepped impedance tunable phase shifter. We give the design of stepped impedance low-pass filter having a maximally flat

response and cutoff frequency of 2.4GHz. In order to tune our circuit characteristics and to modify to insertion phase, we use a varactor diode;

good phase dynamic was obtained with good insertion and return loss

56 Tunable Coupled Line Phase Shifter based on Modified Schiffman Approach Mohamed Ould Elhassen, Mohamed


Ghazel

Abstract :

This paper describes theoretical study, modeling and simulation of tunable coupled line phase shifter. This structure is based on Schiffman model

in which a coupled uniform Microstrip transmission line was used. The main idea of this work is to design a mixed structure tunable phase shifter

using Schiffman model loaded by Varactor diode. We have evaluated the performance of two circuits; a good variation of phase shifting is

denoted with high performances.

http://www.easychair.org/utils/wild.cgi?url=http://imep-lahc.grenoble-inp.fr/


11

Session 2B-2: UWB Saturday AM, March 17, 2012, Room B

Chair: Noureddine HAMDI; Co-chair: Tan-Hoa VUONG

26 Design of Tracking Loop for UWB Systems Rshdee Alhakim, Kosai Raoof and

Emmanuel Simeu

Abstract :

Timing synchronization and tracking represent major challenges in carrying out highly efficient Ultra-WideBand (UWB) communications. The

Delay-Locked Loop (DLL) method is widely proposed to maintain satisfactory synchronization. In this paper, we suggest a novel DLL structure

design for UWB systems based on an approach called Timing with Dirty Template. This approach promises to improve tracking performance

while maintaining low-complexity structure. The parameters of the proposed DLL will be selected to optimize tracking behavior in the presence

of the ambient noise and Doppler effects. Simulation results show noise and transient performance across various parameter values.

52 The Tumor Detection by the UWB Radar Elmissaoui Taoufik and Ridha

Bouallegue

Abstract :

The UWB system in medicine consists of sending electromagnetic waves and analyzing the echo in order to create an image of each layer that

composes the human body. In this paper, we propose a new method which enables us to detect and locate a tumor in the human body. In fact, we

study the electric characteristics of each normal human body layer. Similarly, we present the echo reflected by a normal layer and a layer that

contains cancer. These echoes permit our radar system to detect and locate cancer in each region in the human body. Our system enables doctors

to detect cancer at first stage and that facilitates the treatments.

55 A 60-GHz CPW-Fed Antenna for WPAN Applications Zied Harouni, Lotfi Osman, Amel

Fatnassi and Ali Gharsallah

Abstract : An efficient 60 GHz coplanar waveguide (CPW) fed patch antenna is proposed. This antenna is implemented on a high dielectric constant substrate (εr = 9.9), which is close to the dielectric constant of commercial GaAs and CMOS process. The antenna structure combines the advantages of CPW with those of the aperture-coupled microstrip antenna and simplifies the structure of the antenna by reducing the number of metallization level, from three down to two. This feed design eliminates the competition for surface space between the antenna elements and the feed network.

http://www.easychair.org/utils/wild.cgi?url=http://www.6tel.org


http://www.easychair.org/utils/wild.cgi?url=http://www.fst.rnu.tn/fr/index.php

http://www.easychair.org/utils/wild.cgi?url=http://www.supcom.mincom.tn/fr/




12

Session 2A-3: Codage & MIMO Saturday PM, March 17, 2012, Room A

Chair: Safya BELGHITH; Co-chair: Adnane CHERIF

14 Integration of LDPC codes in MIMO systems Sana Ezzine, Ons Ben Rhouma and

Ammar Bouallegue

Abstract :

Wireless channels are subject to physical constraints responsible for several types of disturbances : noise, fading, multipath propagation,

interference, etc. So it is beneficial to use multiple-antenna systems which are very efficient to reduce the impact of these problems on the

performance of communication system. Furthermore, LDPC codes are error-correcting codes that provide exceptional performance in terms of bit

error probability. We refer to MIMO-LDPC system, the MIMO systems which the LDPC code have been applied.

This paper treats the integration of LDPC codes in MIMO system. For that, we will analyze the performance in terms of bit error rate of multi-

antenna systems by integrating the irregular LDPC codes in those systems according to various parameters such as the number of iterations in

decoding, the number of transmitting antennas, the number of receiving antennas and the length of the LDPC code.We show that the MIMO-

LDPC can achieve the good error rate performance with increased number of iterations in decoding, the number of transmitting antennas and the

number of receiving antennas. We also show that the increase of length LDPC codes does not affect error rate performance.

16 Coded modulations for space-time codes Houda Sboui, Ammar Bouallegue and

Patrick Solé

Abstract :

In this paper, we focus on the case of quasistatic MIMO fading channels when we use concatenated coding schemes. We concatenate tow codes :

an inner code which guarantees full diversity and an outer code which ensures coding gain. An outer code can be designed by taking the quotient

of the algebra by a two-sided ideal which leads to matrices over finite alphabets for the outer code. We present coded modulation schemes for

algebraic space-time codes having the Golden code as inner code.

For the outer code, we begin by studying codes constructions over the finite rings Mn(F3) and Mn(F2) and then we give their multilevels

encoders for these rings.

46 quantum convolutional codes Anis Mahmoudi and Ammar

Bouallegue

Abstract :

The main purpose of this paper is to present a theory of quantum serial turbo codes and describe their iterative decoding algorithm with a

depolarization channel. We define a quantum analogue of a state diagram that provides an efficient way to verify the properties of a quantum

convolutional code, and in particular, its recursiveness and the presence of catastrophic error propagation.

In our constructions, the convolutional codes have thus been chosen to be noncatastrophic and nonrecursive. While the resulting families of turbo

13

codes have bounded minimum distance, from a pragmatic point of view, the effective minimum distances of the codes that we have simulated are

large enough not to degrade the iterative decoding performance up to reasonable word error rates and block sizes.With well-chosen constituent

convolutional codes, we observe an important reduction of the word error rate as the code length increases.

14

Session 2B-3: UWB & RFID Saturday PM, March 17, 2012, Room B

Chair: Fethi CHOUBANI; Co-chair: Khaled GRAYAA

10 Impact of timing mismatch on the performance of a differential receiver Karima Ben Hamida El Abri and

Ammar Bouallègue

Abstract :

This paper studies the influence of timing error on the BER (Bit Error Rate) performance of a DS-UWB (direct sequence ultra wide-band) system.

Through simulation, we show that the reception quality of an UWB system remains good if the error doesn't exceed $3.T_\omega$.

Beyond this value, we constate a degradation of the system performance.

15 Inkjet-Printed rectangular with elements parasitic monopole antenna for RFID applications. Sabri Beldi, Rachida Bedira and Ali

Gharsallah

Abstract :

In this paper inkjet-printed antenna on paper based substrates as solution for the mass production of ultra-low cost Radio Frequency Identification

(RFID). As the growing interest for law cost, flexible, efficient electronics for automatic identification and sensing application increase materials

and integration technique become more complexes.

45 A Broadband Antenna for Passive UHF RFID Tags Mondher Dhaouadi and Mohamed

Mabrouk

Abstract :

A broadband antenna for passive UHF RFID Tag is presented. The reactance component of tag antenna considered chip impedance (-193j) is

conjugated and matched for maximum power transmission. The antenna is fabricated by using Polyester (PET) dielectric substrate with

permittivity 3.2. The size of antenna is 85 × 22 × 0.05 mm. The HFSS simulator is used for optimizing the proposed antenna. The antenna Return

Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 35.3 dB at 914 MHz.

15

Session 2A-4: Complex systems, Localization and Metamaterial Antennas Saturday PM, March 17, 2012, Room A

Chair: Kosai RAOOF ; Co-chair: Larbi HADJ SLAMA

7 Using fuzzy cognitive maps for the modeling of complex systems Farid Lassoued and Ridha Bouallegue

Abstract :

The fuzzy cognitive maps are qualitative tools which can capture the extent from cause to effect in the links that exist within a complex system

such as the information system. These cognitive maps are a simple way of representing knowledge with a huge capacity of interpreting the

information. Indeed, they are exploited for the decision-making, the prediction of future states and the explanation of past actions. Added to these

capacities, when the information is applied and propagated through the model, the topology of the map itself can be used in the diagnosis of

breakdowns by identifying the causes of the nodes of interest.

The main objective of this paper is the conception of impact analysis of engine of rules in an environment object in which objects and their links

of impact (CIs: elementary components of the information system contributing to the delivery of a service), are neither defined nor ordered and

the real time restoration of the results analysis of impact and presentation according to the various orchestrated processes. Thus our role is to

conceive a design of impact analysis and its development guaranteeing in times of answer by using the inference of the fuzzy cognitive maps.

30 A Tri-Band Zeroth-Order Metamaterial-Loaded Monopole Antenna for ISM Applications Nabil Dakhli, Mohamed

Hayouni, Fethi Choubani and Jacques

David

Abstract : The ISM protocol has already been used for a long time to realize customer-specific communication solutions for short and middle distances, which ensure an efficient data transfer, a better reliability and good adaptation for applications which require a low rate of data transfer. The objective of this work is to design a tri-band low-profile small-footprint antenna, which supports the European 434 MHz/868 MHz and the US 315 MHz ISM bands. The radiation mechanism of the antenna is based on the posts, which are connected in series to an inductor at each edge of a transmission line in between. Calibrating the flowing currents in the vias by tuning the inductances values, radiated fields are constructive in the far field region. Full-wave simulations were carried in order to study the properties of the antenna at three different frequencies. The antenna offers a fractional bandwidth of 0.59 %, 0.87% and 2.18%, a radiation efficiency of 12.54%, 38.66% and 77.36% at 315 MHz, 434 MHz and 868 MHz respectively, also a fully omnidirectional, vertically polarized, monopole-like radiation patterns are observed at each band.

38 Indoor Localization using Fingerprinting Technique and Local Linear Estimator Nadia Aloui, Ammar Bouallegue and

Kosai Raoof

Abstract :

In Line-Of-Sight (LOS) environment and Non-Line-Of-Sight (NLOS) circumstances, range-based algorithms such as lateration may fail to offer

good localization accuracy. Therefore, fingerprinting technique is preferred. In this paper, we propose a fingerprinting localization scheme based

on Time Of Arrival (TOA). The estimated TOA is determined by the instant of the maximum cross correlation between the received signal and





16

the source signal. The main contribution of this paper is to apply the kernel linear estimator as a matching algorithm. The simulation results have

shown that the novel localization scheme estimates location within 0.24 m accuracy and 70% precision. Compared to existent algorithms, namely

lateration, nearest neighbor and 4-nearest neighbors algorithms,the proposed scheme brings better performance.

17

Session 2B-4: Acoustic Model; Wavelet; Arabic Speech Saturday PM, March 17, 2012, Room B

Chair: Monia TOURKI; Co-chair: Tahar EZZEDINE

19 Arabic Speech Recognition by Stationary Bionic Wavelet Transform and MFCC using a

Multi Layer Perceptron for Voice Control

Talbi Mourad, Bennasr Mouhamed

and Cherif Adnane

Abstract :

In this paper, we have proposed a new technique of Arabic speech recognition with mono-locutor and a reduced vocabulary. This technique

consists at first step in using our proper speech database containing Arabic speech words which are recorded by a mono-locutor for a voice

command. The second step consists in features extraction from those recorded words. The third step consists in classifying those extracted

features. The features extraction is performed by applying the Stationary Bionic Wavelet Transform (SBWT) to each recorded word at first, the

Mel Frequency Cepstral Coefficients (MFCCs) are computed from the vector obtained from the concatenation of the obtained Stationary Bionic

Wavelet Coefficients. The obtained MFCCs were then concatenated in order to construct one input of a Multi-Layer Perceptual (MLP) used for

features classification. In the MLP learning and test phases, we have used ten Arabic words each of them was repeated twenty five times by the

same ocator. A simulation program used to test the performance of the proposed technique showed a classification rate equals to 98%.

40 Evaluation of an Acoustic Model for Cochlear Implants Based on Frequency Estimation Mourad Ghrissi and Adnen Cherif

Abstract :

Most speech processing strategies in cochlear implants encode only coarse spectral features of the speech signal because of the limited number of

physical electrodes inserted in the cochlea. Some new strategies aim to increase notably the spectral resolution by implementing virtual channels

in order to encode more accurately spectral cues like formant transitions. A new acoustic model for such speech processing strategies is presented

in this paper. It is based on instantaneous frequency estimation within each output of the filter bank. Besides the selection of the frequency bands

used in the stimulation stage is different from previous methods as it is based on the values of the estimated frequencies. Objective analysis of

acoustic models showed that the new strategy encoded more accurately formant transitions when compared to the classic CIS strategy. A

subjective analysis with normal hearing listeners showed that using this strategy yielded to better performance in terms of vowels and consonants

identification when compared to the CIS strategy.

54 OPTIMAL LIFTING BLOCK FOR WAVELET-BASED VIDEO CODING Nabil Chaabani, Tahar Ezzedine and

Ammar Bouallègue

Abstract :

Motion-compensated lifting scheme have become a reference for the temporal filtering of video data. However, blockbased motion estimation and

compensation produce annoying blocking artifacts around the moving objects and near the borders of the images.

In this paper, in the foreground, we will recognize the concept of lifting scheme in general, and then we will give a brief outline on the temporal

lifting scheme of Secker and Taubman, we'll finally explained the method of lifting scheme oriented region where there is a proposed lifting

transformation algorithm in wavelet and justifying the choice of the parameters used.

18

Session 3A-1: Protocols Sunday AM, March 18, 2012, Room A

Chair: Mounir FRIKHA; Co-chair: Kaouther SETHOM

9 Integrating Service Discovery with Reactive Routing Protocol for Mobile Ad Hoc Network Maher Heni and Ridha Bouallegue

Abstract : Mobile ad-hoc networks have a very high increase in academic and industrials areas, and open several research challenges. Results of these challenges are nodes resources that present a critical factor. One of the contributions of ad-hoc networks is that any node can use a service provided by any node in the network and through the multi-hop. This procedure is known as the discovery service. Service is defined as the entity may be a software or hardware that can be used by a user network. To provide these features and meet the requirement to reduce the consumption of critical factors, the aim of this paper is to propose a reliable solution for service data exchange provided by various nodes in the wireless ad-hoc networks and integrate it with a reactive routing protocol. The integration of service discovery with routing protocol present the advantage of running just one layer instead of two and then minimize the waste of resources.

21 Performance of a reconciliation method operating on a discreet quantum key distribution

system

Nedra Benletaief, Houria Rezig and

Ammar Bouallegue

Abstract :

Reconciliation is a mechanism allowing to weed out the discrepancies between two correlated variables. It has great role in every Quantum Key

Distribution protocol where the key has to be transmitted through a noisy channel or as in our case of study in presence of an eavesdropping. In

this paper, we show that for discrete-variable QKD protocols, this problem can be advantageously solved with Turbo codes. In particular, we

demonstrate that our method leads to a significant improvement of Bit Error Rate, may divide it by three in presence of a eavesdropper even with

great eavesdropping capability.

29 Call Admission Control in IEEE 802.16 : Comprehensive Survey and Taxonomy Ahlem Saddoud and Lamia Chaari

Abstract :

WiMAX (worldwide Interoperability for Microwave Access) is the next step in the mobile technology evolution path. It competes with IEEE

802.11-based WLAN technology, broadband residential Internet technologies and third generation cellular technologies. Quality of service (QoS)

is still an important subject that deals with the WiMAX performance. WiMAX can provide QoS guarantees for different service classes with

diverse QoS requirements. Call Admission Control (CAC) is an important QoS component in WiMAX networks as it has a strong relationship

with QoS parameters such as delay, dropping probabilities, jitter and scalability … The IEEE 802.16 standard does not define any CAC scheme

so it is still an open issue for researchers and service providers. The purpose of this paper is to provide a survey on CAC mechanisms in WiMAX

networks. We give an understanding of the different technical issues of CAC approaches that researchers are currently facing to ensure QoS

support in IEEE 802.16 wireless networks. We provide an insight into the new research interest in this field, we classify, and we compare diverse

CAC schemes proposed in the literature.

http://www.easychair.org/utils/wild.cgi?url=http://www.innovcom.org


19

Session 3B-1: Wave Numerical Methods Sunday AM, March 18, 2012, Room B

Chair: Houria REZIG ; Co-chair: Lotfi OSMAN

13 New modal analysis to decompose central arbitrary located source in Planar Almost Periodic

Structures

Bilel Hamdi and Taoufik Aguili

Abstract : In this paper, we provide an effecient new spectral analysis which is important to study a 1-D periodic phased array planar structure excited by arbitrary located sources.The latest demands an accurate evaluation to analyze the modal input impedance in one unit cell with the proper current density appearing on the metal part. The formulation that is proposed to solve the problem allows to study all neighbouring elements in a periodic environment. A Method-of –Moment (MoM) technique based on a simulation code is presented for the analysis of the basic cell (unit cell)

23 Electromagnetic Scattering of a Dielectric Coated Conducting Elliptic Cylinders using WCIP

Method

Jamila Selmi, Rachida Redira and Ali

Garsallah

Abstract :

The problem of scattering of an incident plane wave by metallic and covered objects of arbitrary shape has attracted considerable attention in

telecommunication, antenna design, and electromagnetic compatibility for decades. Many techniques have been proposed to solve the problem of

electromagnetic wave, such as the Moment Method (MOM) and the Finite Element Method (FEM).In this work, the Wave Concept Iterative

Process (WCIP) has been presented and applied to analyse the electromagnetic scattering problems of arbitrary shape bodies. This particular study

was inspired by work to analyse electromagnetic scattering of conductor elliptic cylinder covered with thin dielectric material in free space.

The elliptic cylinders are used to approximately model several real structures, such as aircraft, fuse large and other cylindrical bodies. These

elliptic surfaces can be divided in the small cells, theses cells can be placed on fictitious circular cylinder, so the electromagnetic problem in the

cylindrical coordinates system can be resolved.

Numerical results illustrate the scattering current density and Radar Cross Section (RCS) for different size of a metallic elliptic cylinder, and for

different materials.

43 Numerically Efficient Mode Selection Technique for MoM based Diffraction Analysis Taha Ben Salah, Chiraz Aguili and

Taoufik Aguili

Abstract :

This paper discusses a numerical optimization technique based on mode functions selection for fastening MoM EM analysis of planar obstacles

placed in an infinite waveguide. This technique pretends to give acceptable results while enhancing significantly calculation performance.

Particularly, results for the technique's application on a planar Cantor shaped abstacle are provided

http://www.easychair.org/utils/wild.cgi?url=http://www.enit.rnu.tn/fr/recherches/details_labos.php?id=10


20

Session 3A-2: Channel Estimation & Fuzzy Complex Structures Sunday AM, March 18, 2012, Room A

Chair: Abdellaziz SAMET; Co-chair: Rafik ZAYANI

4 Performance Evaluation of Modified Alamouti Decoding in DVB-T2 Systems using Practical

Channel Estimation

Aymen Omri, Ali Hazmi, Ridha

Hamila and Ridha Bouallegue

Abstract :

In this paper, we present a performance evaluation of an enhanced Alamouti space frequency block decoding scheme for multiple-input multiple-

output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over estimated highly frequency selective channels. This method

uses the variation of the channel frequency response between each consecutive subcarriers to adapt the Alamouti decoder. Simulation results of

DVB-T2 system confirm that this contribution has a good performance in terms of bit error rate when compared to standard Alamouti decoder

over known and estimated highly frequency-selective channels such as single frequency network (SFN) channels.

5 Improving the WCIP method by the contour detection technique and analysis of complex

structures

Hrizi Hafedh

Abstract :

The wave concept iterative procedure (WCIP) is used to analyze high frequency electronic circuits. It is based on the concept of waves in the

place of electromagnetic fields. To study the electronic circuits having complex structures, this method requires much time. In this paper, we

improve the convergence of the WCIP method by adding a new algorithm based on the technique of image contour detection. That’s why the

structure of the studied circuit is considered as an image. The objective is to reduce computing time by reducing dimensions of the calculation

matrices. The reduced matrices are built containing only the important part of the information. Our goal is to prove that the most important zones

in the structure are located in the contour with small steps in the vicinity of the contour.

21

Session 3B-2: Hardware Implantation Sunday AM, March 18, 2012, Room B

Chair: Rached Tourki; Co-chair: Singh SANJEEV

58 Simple power analysis attack on smart card Noura Benhadjyoussef and Hassen

Mestiri

Abstract :

Smart cards are small, portable and tamper-resistant computers. Their uses include security applications ranging from identification and access

control to payment systems and wireless communication framework. A secure smart card has to assurance that secret data like cryptographic key

cannot be recovered or modified by an attacked entity. The purpose of this paper is the implementation of an authentication protocol on smart

card and the analysis of the consumption of this protocol by the Simple Power Attack techniques. (SPA)

59 Implementation of Secured AES Design in CMOS Technology Hassen Mestiri, Noura

Benhadjyoussef and Mohsen

Machhout

Abstract :

The Advanced Encryption Standard (AES) has been thoroughly studied by designers with the goal to improve the performances of the AES

encryption design in terms of area, frequency and power consumption. In this paper, we present the implementation details of the AES encryption

128-bit and the SubBytes transformation. The SubBytes transformation can be implemented using composite field arithmetic in GF((24)2),

GF(((22)2)2) and a multi-stage PPRM architecture. The AES algorithm is implemented using 0.18μm 1.8V Complementary Metal Oxide

Semiconductor (CMOS) technology. A low power consumption of 24.92 μW at 10 MHz was achieved for multi-stage PPRM architecture for

SubBytes transformation.

61 A Hardware implementation of AES-128 on Virtex-5 FPGAs based on different Subbyte

architecture

Nahed Aouf, Mohsen Machhout and

Rached Tourki

Abstract :

One of the best existing symmetric security algorithms is the Advanced Encryption Standard (AES). The three major optimization goals are:

frequency, power consumption and occupation. In this paper we implement an AES pipelined architecture on a single chip of Xilinx Virtex-

5(XC5VLX50FFG676-1) FPGA. Also, we compare three different kind of SubByte implementations as known: the look up table (LUT), GF

(24)2 finite field decomposition and the Positive Polarity Reed-Muller (PPRM), in order to choose the best architecture.

22

Poster Session Session 1

Friday March 16 , 2012 Chair: Hatem BOUJEMAA Co-chair: Fethi TLILI

3 Performance Analysis of a Reactive Routing Protocol for Mobile Ad hoc Networks Maher Heni and Ridha Bouallegue

Abstract : Actually there are much increasing research interest in routing protocols for Mobile Ad Hoc Networks (MANET). This interest is the result of the aim to optimize resource consumption, since they present a critical factor in ad-hoc networks. Works on these protocols focus on protocols behavior modification and performances evaluation in order to reduce consumption of resources. The aim of this work is to evaluate the performances of a reactive routing protocol over mobile Ad hoc Networks called AODV. Computer simulation results show the efficiency of the method and also offer performance measures that agree with competitive methods. The study is conducted over various network topologies and also various terminals mobility mode. In addition various metrics are used for this performance measure mainly: End-to-End Delay, Packet loss, Packet Delivery Ratio and Routing Overhead metric. We also show the robustness of AODV against the terminals mobility and the network size.

6 Possibilistic Localization of Mobile Source Khaoula Baabou, Souhir Fterich and

Hedi Sakli

Abstract :

In order to locate a mobile source in a cellular network, the fusion information is proposed here as an interesting solution to synthesize data. This

approach is increasingly playing an important role in many areas. Many variations are held including the Possibility theory, the subject of our

paper, which we are going to show its use in determining the location of any customer accessing a network. The results would have to properly

reflect these characteristics.

20 Synthesis of Phased Cylindrical Arc Antenna Arrays Using Taguchi Method Amor Smida, Nadhem Nemri, Ridha

Ghayoula and Ali Gharsallah

Abstract :

This paper describes a new approach to synthesize cylindrical antenna arrays controlled by the phase excitation, to synthesize directive lobe based

on Taguchi method. The proposed method is based on iterative minimization of a function that incorporates constraints imposed in each direction.

The results obtained are validated by this method on cylindrical arc Antenna Arrays, which is simulated by CST Microwave.

An 8-element cylindrical arc antenna has been simulated with CST Microwave and tested for various types of beam configurations.

35 Analytical Butterworth-Van Dyke Model of a Ladder BAW Filter Mohamed Ali Boujemaa, Mohamed

Mabrouk and Fethi Choubani

Abstract :

Bulk Acoustic Wave (BAW) filters are specify high Q-factor, high power, integrated RF filters which have proven to be an excellent substitute



23

for conventional RF filters. In this paper, the Butterworth-Van Dyke model is used to model a ladder BAW filter. In order to validate the model,

the analytical results have been compared to the numerical simulation results obtained using the Advanced Design System (ADS). The

comparison shows that the simulation and analytical model's outputs are almost identical.

39 Miniature and Improved Isolation of a 3*3 MMO antennas based on Split Ring Resonator

array

Aouadi Belgacem, Labidi Mondher

and Belhadj Tahar Jamel

Abstract :

In this paper, we study the behavior of a 3*3 Multi-Input Multi-Output (MIMO) antennas like the size and the isolation between the three

radiating elements with and without SRR.

47 Effect of the high impedance surface on the conformal antenna Khaled Jerbi, Mohamed Glaoui and

Ali Gharsallah

Abstract :

we propose to study through this example the influence of high-impedance surface on the inter-element coupling to an conformal antenna. In the

first part, we present the conformal antenna design and its various characteristics. In the second part, we present the properties of and the

geometry of the high impedance surface with vias (Vertical Interconnect Access) that we will use. At the end we will present the architecture of

the antenna with HIS and the result of simulation with CST Microwave and reduced inter-element coupling.

24

Session 2 Saturday March 17 , 2012

Chair: Mohamed SIALA; Co-chair: Sofiane CHERIF

11 A New Scheduling Algorithm For Resource Allocation in LTE Femtocell Networks Kaouthar Sethom, Aicha Ben Salem

and Ridha Bouallegue

Abstract :

Radio Resource Management (RRM) is one of the most challenging and one of the most important aspects of modern wireless communication

networks such as Femtocells. System performance can be improved by applying intelligent radio resource management scheme in wireless

networks. In this paper a new scheduling algorithm based on cooperative game theory is proposed to improve users QoS with respect to its access

priority in LTE Femtocell networks. Each individual user’s goal is to maximize the benefit i.e. the allocated bandwidth

32 Scheduling Schemes Performance Analysis in the LTE-Advanced System with Carrier

Aggregation

Marwane Ben Hcine and Ridha

Bouallègue

Abstract : Carrier Aggregation is the one of the most distinct features of LTE-Advanced. It allows bandwidth extension up to 100 MHz. The use of the appropriate user scheduling scheme assuming different carrier aggregation deployment scenarios is necessary to assure better system performances and optimal use of resources. Assuming carrier aggregation, there are two straightforward scheduling schemes: Separated Random User Scheduling Scheme (SRUS) and Joint User Scheduling Scheme (JUS). First one has simple implementation since it need user equipment to be configured with only one component carrier (CC). The second need user equipment to be configured with multiple component carriers. It is optimal in performance but with high complexity. In this paper, we will study the performance of both scheduling schemes in three deployment scenario: identical coverage, diverse coverage and main beam directed at sector boundaries. The aim of our study is to determine the appropriate scheduling scheme for each deployment scenario. Results show that in diverse coverage ad main beam directed at sector boundaries JUS scheme perform better than SRUS, which can justify the extra control signaling overhead and intensive use of user equipment power. In identical coverage deployment scenario, JUS performances are close to SRUS performances.

60 Blind CFO estimation for OFDM-IDMA system in Rayleigh fading multipath channel Zrelli Yasamine, Houcke Sébastien,

Langlais Charlotte and Ammar

Mahmoud

Abstract :

We address the problem of carrier frequency offset (CFO) in Orthogonal Frequency Division Multiplexing (OFDM) communications systems in

the context of Interleaved Division Multiple Access (IDMA).We propose a technique to adapt a method of blind CFO estimation, called CFO

estimation-Syndrome Function Minimization (C-SFM), to the context of a system combining IDMA and OFDM where a quasi-static Rayleigh

fading multipath channel is considered. Performance in terms of Mean Squared Error (MSE) of carrier frequency offset is studied for a different




25

number of users. In order to evaluate the robustness of the C-SFM method, we compare the performance of OFDM-IDMA system using C-SFM

technique with that of a perfect synchronous system. Our results show that, for high Eb/N0, the two systems have the same performance.

64 Architecture Of Metadata Spatio-Temporal Real-Time For Wireless Sensor Walid Fantazi and Tahar Ezzdine

Abstract :

The information systems containing sensors are more and more used in many applications like the monitoring of the environmental phenomena

(temperature, pressure, humidity, level of CO2, etc). The data gathered by these sensors are space-time data relating to the phenomena observed

thus that the elements to measure. Within the framework of this article we developed an approach for the installation of a communicating space-

time database with an application (Web mapping) which satisfies the needs of users for the management (structuring and the exploitation) of

space-time data within databases sensors. Thus, and according to the data necessary during a time interval and integrated in the database, the

developed interface will make it possible to reach and handle the data, like ordering the operation of the sensors in real-time. This approach will

be applied in the environmental field.

65 Tunable RF Bandpass Filter using Loaded Square Ring Resonator Bousbia Leila and Mohamed Mabrouk

Abstract : In this work, the design procedure, modeling and implementation of reconfigurable filters based on coupled open loop rings resonators is presented. A tunable band-pass filter capable of controlling center frequency bandwidth and selectivity is proposed. The device is tuned by varactor diodes placed at the inner of the open loop ring resonator. Our Simulations show a tunable center frequency range from 2.2GHz to 2.43 GHz, a tunable fractional bandwidth range from 11.36% to 14.81%, and a tunable selectivity range from 0.36 to 0.7.

http://www.easychair.org/utils/wild.cgi?url=http://www.supcom.mincom.tn

26

Session 3 Sunday March 18 , 2012

Chair: Ali HAZMI; Co-chair: Ammar SHARAIHA

8 Novel Timing Acquisition Approach for UWB Systems Moez Hizem and Ridha Bouallegue

Abstract :

In this paper, the goal is to investigate the timing acquisition problem for ultra wideband (UWB) systems using time hopping (TH) spreading.

Low-complexity timing acquisition represents a main challenge to achieve the high potential UWB technology expectations for indoor wireless

communication. For this reason, to address this constraint, we propose and test a new timing acquisition algorithm based on two-stage acquisition

scheme. Applied in [1-4], our algorithm is a combination between coarse synchronization based on timing with dirty templates (TDT) acquisition

scheme and a new fine synchronization algorithm which conduct to an improved estimate of timing offset. We develop this method in both data-

aided (DA) and non-data-aided (NDA) modes. Simulation results show a significant performance improvement in the NDA mode and a small one

in the DA mode. These results are realized in terms of the main square error (MSE) and especially in the acquisition probability, comparing to the

original TDT approach in which the performance degrades to the random symbol effect.

22 Contribution to the optimization of Point-to-Point Systems MIMO Performance with Partial

Channel State Information

Rajoua Anene and Ridha Bouallegue

Abstract :

The main purpose of this paper is to study the performance of the Multiple-input multiple-output (MIMO) wireless communication. MIMO

Systems have the potential to provide high data rates, the evolution of these systems builds upon the ability to furnish high rates with the channel

state information at the transmitter (CSIT), even if obtaining CSIT is a complex task because the resources on the feedback link is very limited.

Therefore, we propose to study the optimization of MIMO wireless communication systems with partial channel state information.

In this paper we propose techniques to exploit the available sources of CSIT in order to optimize the system performance.

Firstly, point-to-point MIMO channels are considered for the aim of error rate minimization.

Secondly linear precoding techniques are proposed to enhance the performance of space-time coded (STC) MIMO systems, based on statistical

information on the MIMO channel.

Computer simulations show that, the performance of such systems can be ameliorates by appropriately combining mean and covariance

information.

33 BER PERFORMANCE OF NEURAL NETWORK COMPENSATOR IN FREQUENCY

DOMAIN BASED MMSE RECEIVER FOR HPA NONLINEARITY IN MIMO OFDM

SYSTEMS

Maha Cherif Dakhli, Rafik Zayani and

Ridha Bouallegue

Abstract :

In this paper, we present a method based on Neural Network (NN) technique in frequency domain and accompanied with MMSE(Minimun Mean

Square Error), which corrects at the receiver level, the Non-linear (NL) distortions due to HPA (Hiqh Power Amplifier). The neural network

27

consists on a feed-forward Multi-Layer Perceptron (MLP) associated with Levenberg)Marquardt learning algorithm. The results show a BER

performance of neural network compensator in frequency domain in a VBLAST MIMO OFDM (Vertical Bell Layered Laboratories Space-Time

Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing) system running under a Rayleigh fading channel.

42 RECEIVER TECHNIQUE FOR THE COMPENSATION OF HPA NONLINEARITY IN

STBC BASED COOPERATIVE AMPLIFY-AND-FORWARD OFDM SYSTEMS

Hela Hizaoui, Rafik Zayani, Ridha

Bouallegue

Abstract :

In this paper, we investigate the effects of high-power amplifier (HPA) nonlinearity on the performance of wireless multiple antenna orthogonal

frequency-division multiplexing (MIMO-OFDM) systems, especially for the Alamouti Space Time Block Coding (STBC) case.

We propose a compensation method for this nonlinearity at the receiver side. The performance of the cooperative STBC-MIMO-OFDM system

equipped with the proposed compensation schema is evaluated in terms of Bit Error Rate (BER) when transmissions are performed over

uncorrelated Rayleigh fading channels. Numerical results are validated by MATLAB simulation and show the high improvements in terms of

BER especially for high SNR values.

49 Mobile Localization Using Channel Impulse Response Fingerprinting And Neural Networks Raida Zouari, Rafik Zayani and Ridha

Bouallegue

Abstract :

In recent years, there has been a growing interest in the mobile network for a variety of interior applications such as the location of people in

confined spaces and underground. Indeed, the location of people, mobile terminals and equipment is most desirable for security and operational

enhancements in mining. Due to the special nature of underground environments, traditional localization techniques based on RSS, AOA, TOA

and TDOA cause in the deterioration of the positioning performance. In this paper, we study a method for mobile localization which combines

Channel Impulse Response (CIR) fingerprinting and Neural Network (NN) techniques.

28

Contact

Takwa BOUALLEGUE

Phone : +(216) 55 40 45 19

e-mail : [email protected]

www.6tel.org / www.innov-com.org

mailto:[email protected]

http://www.6tel.org/

http://www.innov-com.org/

A Broadband Antenna for Passive UHF RFID Tags

Abstract— A broadband antenna for passive UHF RFID Tag is presented. The reactance component of tag antenna considered chip impedance (-193j) is conjugated and matched for maximum power transmission. The antenna is fabricated by using Polyester (PET) dielectric substrate with permittivity 3.2. The size of antenna is 85 × 22 × 0.05 mm. The HFSS simulator is used for optimizing the proposed antenna. The antenna Return Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 35.3 dB at 914 MHz. Keywords: Broadband antenna; tag antenna; RF identification (RFID)

I. INTRODUCTION

Radio-Frequency IDentification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders [1]. First functional passive UHF RFID systems with a range of several meters appeared in early 1970’s [2]. Since then, RFID has experienced a tremendous growth. RFID UHF bands vary in different countries and include frequencies between 860 MHz and 960 MHz (EPC global standard) [3]. Most popular UHF RFID standards are ISO 18000-6B and recently ratified EPC Gen2.

UHF RFID Tags communicate with the reader using backscatter principle. The chip in the tag harvests the RF power transmitted by the reader in order to provide power supply for the chip. The chip uses this power to switch between two impedance states [4, 5]. This change in impedance state modulates the signal backscattered by the RFID Tag antenna and Tag uses this to communicate back to the reader.

Licensed frequency spectra for UHF RFID applications varies from one country to another, such as 866-869 MHz in Europe, 902-928 MHz in North and South America, 840-845 MHz and 920-925 MHz in China, and 950-956MHz in Japan.

RFID tag antenna normally operates on a single frequency. Specifically, the antenna has a narrow bandwidth. However, we do not have complete control over the environment of the tag antenna. If an RFID tag is designed to be resonant at the right frequency when it is placed on an empty box, it might move to the wrong frequency when the box is filled with metal cans, or even just placed near another box filled with metal cans. Or, if the RFID tag is designed to operate on a box filled with metal cans, it might move to a wrong frequency when the box is filled with glass bottles. Thus, we must design the RFID

tag to have a bandwidth wide enough to take into account all possible changes in its environment.

However, it is hard to design a tag antenna for passive UHF RFID applications because the attached microchip has a high quality factor that has small resistance and large capacitive reactance at its terminals, which makes it not easy to attain a wideband characteristic for the tag antenna.

A broadband UHF RFID tag antenna using double symmetrical radiating patches shorted to ground plane with T-matching network was reported [6] and its bandwidth approximately covered the UHF RFID bands. But this design requires the use of multi-layered substrate which results in a required large and complex antenna volume (106*44 mm), low flexibility, and high cost of the antenna.

In this paper, we propose a novel broadband UHF RFID tag antenna. The proposed antenna has a bandwidth from 660 MHz to 1020 MHz (S11< -10 dB) for conjugate matching with a commercial tag chip and its bandwidth cover all UHF RFID frequency bands. The proposed antenna also has the advantages of simple structure, small size, low cost, and high flexibility.

II. ANTENNA DESIGN

The proposed antenna structure is shown in Fig. 1.

(a)

Figure 1.Geometry of the proposed broadband tag antenna

(a) Top view (b) Side view

(1)M. Dhaouadi, (1)M. Mabrouk, IEEE Member, (1)A. Ghazel, IEEE Senior Member and

(2)S. Tedjini, IEEE Senior Member (1)CIRTACOM, SUPCOM-ISETCOM de Tunis, University of Carthage,

City of Communication Technologies, 2083, Tunisia (2)ORSYS, LCIS, ESISAR-INPG, 50 rue de Laffemas, BP 54, 26902, Valence Cedex 9, France

[email protected]

[email protected]

The antenna is fabricated with a flexible polyester (PET) substrate (thickness 50H mµ= , relative dielectric constant

3.2rε = , and loss tangenttan 0.003δ = ) with an overall size

of 85 × 22 mm2. The detailed dimensions of the antenna prototype are: LS=85mm, L1=22.5mm, L2=22mm, L3=3mm, L4=34mm, WS=22mm, W1=5mm, W2=3mm, W3=1mm, W9=15mm, W10=5mm, W11=2mm. The operation frequency of the tag is in the UHF band. For the purpose of design calculations, the frequency of 915 MHz has been chosen.

Integrated chip ASIC Philips (NXP UCODE) enclosed in TSSOP8 body was used for the tag [7]. For maximum power transfer between the tag antenna and the RFID IC, the tag antenna impedance must be the complex conjugate of the RFID IC impedance. The RFID IC impedance is highly capacitive in nature the conjugate match in predominantly inductive. In this paper the antenna is designed for a tag chip with

Ω−= )19322( jZ c at a resonant frequency of 915 MHz. The

load antenna impedance should be Ω+= )19322( jZ a for

conjugate matching and to transmit the maximum power between the antenna and the microchip.

III. RESULTS

The antenna was designed using electromagnetic simulation tool Ansoft HFSS which allowed us to calculate antenna gain, impedance, and proper matching to the RFID chip. The return loss -35.3 dB is obtained at the frequency 914 MHz is shown in Fig.2.


Fig.3 shows the predicted VSWR performance of the antenna vs frequency (at 914 MHz).

Figure 3. Antenna Impedance Against Frequency:

Resistance Component Ra, Reactance Component Xa



The proposed antenna also has the broad impedance bandwidth with approximately 360 MHz at -10dB return loss for conjugate matching with a commercial tag chip and its bandwidth covers all UHF RFID frequency bands. The maximum simulated gain is 1.7 dB at 914 MHz.

IV. CONCLUSION

In this paper, the proposed antenna also has good characteristics low cost, low complexity, and high flexibility. In the future, the antenna reduction and measurement will be investigated.

REFERENCES [1] K. Finkenzeller, “RFID Handbook,” 2nd ed., John Wiley & Sons, 2003

[2] S.Tedjini, T. Vuong, “Radio Frequency Identification, a technology for the future,” URSI (Union Radio-Scientifique Internationale), in Chicago, USA, August 2008.


[4] Lindsey, J. F., “Radar Cross-Section Effects Relating to a Horn Antenna”, IEEE Transactions on Antennas and Propagation, vol. 37, no. 2, pp. 257-260, February 1989.


[6] Xu,L.,B.J, and Wang, J.,”UHF RFID tag antenna with broadband characteristic,” Electron. Lett.,2008,44,(2),pp. 79-80

[7] UCODE G2XM and UCODE G2XL (TSOOP8 Package Specification) from December 2007, http://www.nxp.com/ .

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Magnetic Antenna for Near-field UHF RFID Tag

Abstract— In this paper, we propose a method of the improvement of performance of UHF RFID Tag antenna in near field. Currently, near-field UHF RFID receives a lot of attention as a possible solution for item level tagging in various applications.

I. INTRODUCTION Radio-Frequency IDentification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID Tags or transponders [1]. Near field RFID are based on inductive coupling between the reader and the Tag. The magnetic field induction between the reader and Tag enables communication. UHF near-field RFID technology receives a lot of attention owing to the promising item-level applications for pharmaceutical [2-3]. It appears today that one of the limitations of UHF Tags is that they do not function at short distances (near field). As a result, this greatly spurs the investigation into antennas for UHF near-field applications.

In this paper, we concentrate on the improvement of performance of UHF RFID Tag antenna in near field.

II. NEAR-FIELD UHF RFID SYSTEMS The basic near field UHF RFID concept is to make UHF RFID system work at short distances and on different objects as reliably as LF/HF RFID [4-5]. RFID has numerous frequencies (LF, HF, UHF and Microwave) and each frequency has its advantages (LF is the most metal friendly frequency) and disadvantages (UHF is not water friendly). Near-field UHF technology is capable of transmitting in the near-field, similar to HF, but is faster and works well around metals and liquids [3]. Since the major part of reactive energy is stored in the magnetic field, the system of inductive coupling is preferred for the communication between the antenna of reader and the antenna of Tag. Most of the near field UHF RFID Tags antennas are rectangular or circular loops, as these electrically small loop antennas are able to produce a strong and uniform magnetic field in the region around the antenna.

Finally, to have a good magnetic coupling in near field UHF RFID Tag antenna, it is necessary to use T-match configuration [6] with a circular or rectangular for tags antennas. The electromagnetic waves can be dispersed by the antenna with inductively coupled feed because this method of feed generates a discontinuity of magnetic field and electric between the loop and the radiating body [7].

III. TAG ANTENNA ANALYSIS

A. Tag Antenna Design The structure of the proposed antenna is presented in Fig.1.

Figure 1. Tag antenna structure with T-match configuration The tag antenna was small meander dipole on a polyethylene substrate (thickness h = 1.57mm, relative dielectric constant 25.2=rε , and loss tangent 01.0tan =δ ). The dimensions of the antenna prototype are a=112mm, b=120mm, c=83mm, d=27mm, e=9mm, as well as the details of the antenna are illustrated in Fig. 1. The antenna was designed for an RFID tag chip with Ω−= )15512( jZ c . The resonant frequency of the radiating body is 900 MHz.

IV. RESULTS

A. Antenna Performance The tag antenna is analyzed by the HFSS software; the performance of the antenna is calculated. Fig.2 shows the measured return loss and the impedance against frequency is plotted in Fig. 3.

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M. Dhaouadi, M. Mabrouk, IEEE Member and A.Ghazel, IEEE Senior Member CIRTACOM, SUPCOM-ISETCOM de Tunis, Cité Technologique des Communications, 2088, Tunisia

Tél. : +216-71-857000, Fax : +216-71-8575555 [email protected]

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The proposed antenna for the near-field distribution characteristic also has the broad impedance bandwidth with approximately 32MHz at -10dB return loss. The maximum simulated gain is 6.09 dB at 900 MHz.

B. Field Analysis of Tags Antennas

The current on a side of the rectangular feed loop (a) is not same magnitude as that on other side of the radiating body but it is reduced progressively. The current fluctuation generates a variation of magnetic field. Then the strength of the magnetic field decreases with the diminution of the current. The reduction in the magnetic field produces a distribution of this field which is not uniform for near-field RFID applications.

(a) Magnetic field plot of the antenna with inductively coupled feed

(b) Magnetic field plot of the antenna using T-match configuration.

Figure 5. Simulated near-field plots of UHF RFID tag antenna

Fig.5 shows the difference of the distribution of magnetic field in near-field between RFID tag antennas using an inductively coupled feed and RFID tag antennas using T-match configuration.

V. CONCLUSIONS The performance of system near-field to RFID is improved with the use of RFID tag antennas using T-match configuration. From the simulation results, we confirmed that antennas using T-match configuration conserves the near magnetic field for an induced current more than an antenna with inductively coupled feed. Similar to near-field UHF RFID tag, the UHF near-field RFID reader antenna must be to study to increase the magnetic field between the two antennas.

REFERENCES [1] K. Finkenzeller, “RFID Handbook”, 2nd ed., John Wiley & Sons, 2003 [2] “Item-level visibility in the pharmaceutical supply chain : a comparison

of HF and UHF RFID technologies”, http://www.tagsysrfid.com/modules/tagsys/upload/news/TAGSYSTI-Philips-White-Paper.pdf

[3] C. Swedberg, “A Shift to UHF Near-Field Predicted for Pharma”, RFID Journal,2005, www.rfidjournal.com/article/.../rfidjournal-article2694.PDF

[4] P.V. Nikitin, K.V.S. Rao, S. Lazar, “An Overview of Near Field UHF RFID” , IEEE International Conference on RFID 2007

[5] P. Harrop, “Near field UHF vs. HF for item level tagging”,IDTechEx article, available at http://www.eurotag.org/?Articles_and_Publication

[6] G. Marrocco, “The art of UHF RFID antenna design : impedance-matching and size-reduction techniques”, IEEE Antennas and Propagation Magazine, Vo.50, N° 1, January 2008

[7] H. H. W. Son and C.S. Tyo, “Design of RFID tag antennas using an inductively coupled feed”, Electronics Letters, 41,18 September 2005, pp. 994-996.

Final Poster Session

RWS Review Decision

Date: September 29, 2014 15:52:03 Expéditeur: RWW2015 TPMSv2 (Technical Program Management System v2) <[email protected]> Répondre à: Jeremy Muldavin<[email protected]> Destinataire: [email protected] Sujet: 307 (Paper#) RWS Review Decision

En-tête complet

Please: Do not reply to this message. Please: See below for points of contact and their e-mail addresses. Dear Dr. Mondher Dhaouadi On behalf of the RWS Technical Program Committee, we are pleased to inform you that your submitted paper (Registration Key: OGST0uFmMiZv) entitled, A Capacitively-loaded Loop Antenna for UHF Near-field RFID Reader Applications (Paper #307), has been accepted for presentation at RWW2015. Thank you so much for your submission and participation in RWW this year. Your paper is contributing to a strong technical program. Final Paper Submission is due November 4, 2014. Detailed instructions on the submission will be available at the RWW 2015 website (http://www.radiowirelessweek.org). Final Room numbers and Locations will be updated in the near future. Your paper is scheduled as a Poster presentation. Your Poster paper has the unique identifier: WE3P-8 (which should be used in any correspondence). Poster Session WE3P is tentatively scheduled to be held in Room E on Wednesday, January 28, 2015 starting at 1250. You must remain with your Poster during the entire 110 minute duration of the Poster Session. Please consult the RWW2015 website periodically for room changes, etc. Thank you for your patience and participation in RWW 2015. See you in San Diego! Your Session Chair and Co-chair are: Chair's name: Yupeng Jia

Chair's affiliation: National Instruments Chair's e-mail: [email protected] Co-Chair's name: Co-Chair's affiliation: Co-Chair's e-mail: Again, congratulations on your paper acceptance, and we look forward to seeing you at RWS. Best regards, Jeremy Muldavin [email protected] Technical Program Chair(s), RWW2015

Magnetic feeding for UHF-RFID Tags AntennaM. Dhaouadi1 , M. Mabrouk1, IEEE Member, A. Ghazel1 , IEEE Senior Member, S. Tedjini2, IEEE Senior Member

1CIRTACOM, SUPCOM-ISETCOM de Tunis, Cité Technologique des Communications, 2088, Tunisia2ORSYS, LCIS, ESISAR-INPG, 50 rue de Laffemas, BP 54, 26902, Valence Cedex 9, France

BACKGROUND

Radio Frequency Identification (RFID) is changing our live styles and relations with our environment

RFID systems are closely depending on Tag functioning reliability

Some limitations in Near Field region, so Tag Antenna has to be carefully designed and matched

Tag Antenna = Rectangular Loop + Radiating Body

Inductive coupling is used between Tag antenna and feeding loop (closely placed near radiating body)

Input impedance :

Loop impedance :

Mutual inductance :

Prediction of impedance of Tag Antenna at resonance :

Input resistance Rin and reactance Xin of Tag antenna can be adjusted and matched to chip impedance.

PURPOSE AND HYPOTHESIS

Equivalent circuit of the radiating body

Equivalent circuit of the feed loop

Chip terminals

Zin

M

Ra

Ca

La

Lloop

Feeding loop

Chip

Radiating body

a

2

loopin ZM.f..2ZZ

looploopL.f..2.jZ

aloopL.LKM

a

a

2

0

0inR

R)M.f..2()f(R

loop00inL.f..2)f(X

Tag Antenna with inductive coupling designed on FR4Substrate with Permittivity = 4.4, Dissipation Factor = 0.02and H=0.8mm

STRUCTURE DESIGN

W

L

L1L2

L3

W1

Antenna Dimensions :Wsub=108.0mm,Lsub=106.4 mm,W=88.0 mm, L=24.7 mm,L1=32.0 mm, L2=14.0 mm,L3=14.0mm and W1=43.0mmChip impedance :Zc= (22 – 193j)

SIMULATION RESULTS

Simulated current distribution at 866MHz

800.00 850.00 900.00 950.00Freq [MHz]

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

dB(S

(Lum

pPor

t1,L

umpP

ort1

))


m1

Curve Info


m1 866.6667 -32.1241

800.00 850.00 900.00 950.00Freq [MHz]

0.00

100.00

200.00

300.00

400.00

500.00

Y1


m1

m2

Curve Info



Name X Y

m1 866.6667 12.5672

m2 866.6667 195.0187

800.00 850.00 900.00 950.00Freq [MHz]

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

dB(V

SWR

(Lum

pPor

t1))


m1

Curve Info


Name X Y

m1 866.6667 0.4303

Antenna Return Loss

-30.00

-28.00

-26.00

-24.00

90

60

30

0

-30

-60

-90

-120

-150

-180

150

120

Ansoft Corporation HFSSDesign1Radiation Pattern 1Curve Info


Antenna Impedance

Radiation Pattern (=90)

Antenna VSWR

CONCLUSIONS• Inductive coupling to feed antenna for

UHF RFID Tag and ensure near field functioning

• Modeling and simulation give good results

• Improvements will be carried to reduce antenna global size.

BIBLIOGRAPHY

[1] L. Yang, S. Basat, and M. M. Tentzeris, "Design and Development of Novel Inductively Couple RFIDAntennas", Procs. of the 2006 IEEE-APS Symposium, pp.1035-1038, Albuquerque, NM, July 2006

[2] H. W. Son and C.S. Tyo, "Design of RFID Tag antennas using an inductively coupled feed",Electronics Letters, September 2005, pp. 994-996.

Final Poster Session

RWS Review Decision

Date: September 29, 2014 15:52:03 Expéditeur: RWW2015 TPMSv2 (Technical Program Management System v2) <[email protected]> Répondre à: Jeremy Muldavin<[email protected]> Destinataire: [email protected] Sujet: 307 (Paper#) RWS Review Decision

En-tête complet

Please: Do not reply to this message. Please: See below for points of contact and their e-mail addresses. Dear Dr. Mondher Dhaouadi On behalf of the RWS Technical Program Committee, we are pleased to inform you that your submitted paper (Registration Key: OGST0uFmMiZv) entitled, A Capacitively-loaded Loop Antenna for UHF Near-field RFID Reader Applications (Paper #307), has been accepted for presentation at RWW2015. Thank you so much for your submission and participation in RWW this year. Your paper is contributing to a strong technical program. Final Paper Submission is due November 4, 2014. Detailed instructions on the submission will be available at the RWW 2015 website (http://www.radiowirelessweek.org). Final Room numbers and Locations will be updated in the near future. Your paper is scheduled as a Poster presentation. Your Poster paper has the unique identifier: WE3P-8 (which should be used in any correspondence). Poster Session WE3P is tentatively scheduled to be held in Room E on Wednesday, January 28, 2015 starting at 1250. You must remain with your Poster during the entire 110 minute duration of the Poster Session. Please consult the RWW2015 website periodically for room changes, etc. Thank you for your patience and participation in RWW 2015. See you in San Diego! Your Session Chair and Co-chair are: Chair's name: Yupeng Jia

Chair's affiliation: National Instruments Chair's e-mail: [email protected] Co-Chair's name: Co-Chair's affiliation: Co-Chair's e-mail: Again, congratulations on your paper acceptance, and we look forward to seeing you at RWS. Best regards, Jeremy Muldavin [email protected] Technical Program Chair(s), RWW2015

International Conference on Information Processing and Wireless Systems

March 16, 17 and 18 2012, Tej MARHABA Sousse Tunisia

2

Planning

Friday March 16, 2012 Saturday March 17, 2012 Sunday March 18, 2012

8:00 - 8:30

Registration

Registration Registration

8:30 - 9:00 Plenary Session 2 Plenary Session 4

9:00 - 9:30



Oral Sessions Room A : Papers 9, 21 and 29

Room B : Papers 13, 23 and 43 10:00 - 10:30

10:30 - 11:00 Coffee Break Coffee Break


Oral Sessions Room A : Papers 4 and 5

Room B : Papers 58, 59 and 61 11:30 - 12:00

12:00 - 12:30 Poster Sessions 2 Papers 11, 32, 60, 64 and 65

Poster Sessions 3 Papers 8, 22, 33, 42 and 49 12:30 - 13:00

13:00 - 13:30

Lunch Lunch Closing and Lunch 13:30 - 14:00

14:00 - 14:30

14:30 - 15:00

15:00 - 15:30 Allocution of the Minister of Higher Education and Scientific Research (15’)

Allocution on The Minister of Communication Technologies (15’)

& Plenary Session 1 (60’)

Plenary Session 3

15:30 - 16:00


16:30 - 17:00 Coffee Break


Coffee Break



18:00 - 18:30 Poster Sessions 1 Papers 3, 6, 20, 35, 39 and 47

18:30 - 19:00

20:00 GALA DINNER

3

Oral Session

Session 1A-1: MIMO OFDM Friday PM, March 16 , 2012, Room A

Chair: Ammar BOUALLEGUE ; Co-chair: Hichem BESBES

ID Title Authors

18 Joint ML and MAP Channel Estimation for MIMO-OFDM System Under High Mobility

Conditions

Zaier Aida and Bouallegue Ridha

Abstract :

In this paper, we propose an improvement of the Maximum Likelihood estimator in a MIMO OFDM (Multi Input Multi Output - Orthogonal

Frequency Division Multiplexing) system. As known, the combination between the two techniques allows spectral efficiency and increased

throughput.

Thus, this work focuses on channel estimation in a MIMO context based on a rigid estimator which is the maximum likelihood one and which has

been used as a tracker of the channel in others works. Then, we will compare the performance of this estimator with the Maximum A Posteriori

one (MAP) since it demonstrates too its effectiveness.

The performance of the estimator will be expressed in term of bit error rate BER versus the signal to noise ratio SNR. For a (2,2) MIMO system,

our simulations results shown a great enhancement comparing to related works as for different schemes of the MIMO system .

62 PAPR reduction for SFBC MIMO-OFDM systems Laabidi Mounira, Zayani Rafik and

Boualleugue Ridha

Abstract : Multiple input multiple output techniques, combined with orthogonal frequency division multiplexing (MIMO-OFDM), provide a promising approach for wireless systems. However, a serious drawback of the OFDM system consists in the high peak-to-average power ratio (PAPR) which may severely affect the power efficiency of RF power amplifiers. In this paper, we propose two methods to reduce the PAPR of SFBC MIMO-OFDM signals based on the rotation and inversion across antenna. To secure the efficiency of these methods, we compare them with Polyphase Interleaving and Inversion method.

63 Mimetic Crossover Neural Network Predistortion for the compensation of memory crosstalk

and HPA nonlinearity effects on MIMO-OFDM systems

Hanen Bouhadda, Rafik Zayani, Ridha

Bouallegue and Daniel Roviras

Abstract : In this paper, we investigate the joint effects of memory crosstalk and HPA nonlinearity in multicarrier OFDM-MIMO systems by proposing a new structure of Neural Network Predistortion which consists to eliminate those effects. Then, we will compare those results with those already obtained in [1].

4

The algorithm used to train the neural network is the Levenberg-Marquardt one (LM), which has proven in [2] to exhibit a very good performance with lower computation complexity and faster convergence than other algorithms used in literature. The present results where observed for the Alamouti STBC MIMO-OFDM system in terms of Bit Error Rate (BER) in Rayleigh fading channel.

5

Session 1B-1: Antennas Friday PM, March 16 , 2012, Room B

Chair: Taoufik AGUILI; Co-chair: Henri BAUDRAND

12 Interaction between Five-Layered Human Head Model and a Half- Wave Dipole Antenna Hafawa Messaoudi and Taoufik Aguili

Abstract : The interaction between a five-layered human head model and a half-wave dipole antenna is analyzed in this paper. It is well known, that some of the radio waves emitted by a mobile phone handset are absorbed by the human head. The specific absorption rate (SAR) is a defined rate to evaluate the power absorbed by biological tissue. The results show that the SAR distribution is influenced by various parameters such as antenna position relative to the human head, polarization and distance, the shape and geometry of the head. Whether or not those parameters affect significantly antenna performances specially its radiation pattern. The antenna radiation pattern and other characteristic are significantly altered by the presence of the human head.

17 Synthesis and implementation of Phased Circular Antenna Arrays Using Taguchi Method Nadhem Nemri, Amor Smida, Ridha

Ghayoula, Hichem Trabelsi and Ali

Gharsallah

Abstract : This paper is aimed at assessing the effectiveness of the phase-only control strategy based on a customized Taguchi method when applied to Uniform Circular Arrays (UCA). The objective of this paper consists to contribute the main lobe optimization of the smart antenna using Taguchi's method. We used the cited method in order to determine phase's weights for each element of the circular antenna array in order to steer the principal lobe from -65° to 65° covering all angular space. After that, we made an electronic platform using the microcontroller STM8S in order to implement an intelligent system. The architecture of this work had used a digital phase shifters, a demodulator AD8347, a modulator AD8349, an array antenna, cards STM8S-Discovery.

50 A Smart Antenna System based on Planar Array Antenna Faten Ben Ghenaya and Ridha

Ghayoula

Abstract : In this paper, a novel design of smart antenna system based on planar (ring) array antenna beamforming is proposed. The goal of the design is to construct smart antenna beamforming systems with uniformly spaced radiating elements and with equal amplitude and phase excitation have long been used for the purpose of obtaining good omnidirectional patterns in the plane of the array. However, the mutual coupling effects will be introduced. To verify the performances of the proposed technique, a 4-elements array has been realized and tested for various types of beam configurations.




6

Session 2A-1: LTE Saturday AM, March 17 , 2012, Room A

Chair: Neji YOUSSEF ; Co-chair: Adel GHAZEL

1 Performance Evaluation of a Hybrid LS-LMMSE Channel Estimation Technique for

different LTE Downlink Systems


Bouallegue

Abstract : In this paper, we propose to study the performance of the hybrid LS-LMMSE channel estimation technique for different LTE Downlink systems. LTE Downlink system is based on a MIMO-OFDMA technology. In OFDM systems, in order to mitigate both inter-carrier interference (ICI) and inter-symbol interference (ISI) caused by the multi-path propagation, a cyclic prefix inserted at the beginning of each transmitted OFDM. The inserted cyclic prefix length is defined to be equal to or longer than the channel length. However, and due to some unforeseen channel behavior, the cyclic prefix can be shorter than the channel length. In previous works, we have studied the performance of Least Square (LS) and Linear Minimum Mean Square (LMMSE) estimators under the effect of the channel length, we have concluded that in the case where the cyclic is equal to or longer than the channel length, LMMSE performs better than LS estimator. In the other case, LMMSE still performs better than LS estimator but this time for only low SNR values. For high SNR values, LS estimator shows better performance. Therefore, we have further proposed a hybrid LS-LMMSE channel estimator robust to the channel length effect. LTE provides a scalable bandwidth from 1.25 MHz to 20 MHz. Each LTE downlink system has its own technical specifications in terms of frequency sampling, FFT size,… In this paper, we will study the performance of the proposed hybrid LS-LMMSE channel estimator for different LTE Downlink systems. MATLAB Monte –Carlo simulations are used to evaluate the performance of this estimator in terms of Mean Square Error (MSE) and Bit Error Rate (BER) for 2x2 LTE Downlink systems under the channel length effect.

2 Performance of Channel Estimation Techniques for LTE Downlink Systems under the

Channel Length Effect


Bouallegue

Abstract : In this paper, we propose to study the impact of the channel length of the performance of channel estimation techniques for LTE Downlink systems. LTE Downlink system is a multiuser system based on a MIMO-OFDMA technology. Usually, in OFDM systems, before transmitting an OFDM symbol, a guard interval called cyclic prefix (CP) is inserted at the beginning of each transmitted OFDM symbol in order to mitigate both inter-carrier interference (ICI) and inter-symbol interference(ISI). Usually, the inserted cyclic prefix is chosen equal to or longer than the channel length. However, because of some unforeseen channel behavior,the cyclic prefix can be shorter. In this paper, we interest to study the performance of channel estimation techniques in the two cases.Simulations results show that in the case where the cyclic prefix is equal to or longer than the channel length, LMMSE and SVD estimators perform better than LSE but at the cost of computational complexity. LSE performs better than SVD estimator only for very high SNR values.In the other case, LMMSE and SVD estimators look to perform better than LS but only for low SNR values. In the other hand, LS looks the better for LTE Downlink systems for high SNR values. MATLAB Monte–Carlo simulations are used to evaluate the performance of LS, LMMSE and SVD in terms of Mean Square Error (MSE) and Bit Error Rate (BER) for 2x2 LTE

7

Downlink systems under the channel length effect.

31 A Study of Channel Estimation for 3GPP’s SPATIAL CHANNEL MODEL Extended in

Downlink LTE Systems

Samia Dardouri and Ridha Bouallague

Abstract : In this paper, we study the channel estimation algorithms for the downlink LTE systems of 3GPP. By using computer simulation, the pilot signal assisted channel estimation algorithms based on least square (LS), linear minimum mean square error (LMMSE) criteria and SVD-LMMSE channel estimation, together with channel interpolation based on linear interpolation. The channel model is chosen as a typical urban scenario modeled by Spatial Channel Model Extended (SCME), which is implemented with the LTE downlink structure in this paper. The performance is measured using the mean square error (MSE) between LMMSE estimator with optimal rank reduction by singular value decomposition (SVD) can improve the estimation performance effectively. All channel estimation algorithms are simulated. The simulation conclusion is that the new channel estimations are more efficient. We conclude that the channel frequency responses of pilot tones are estimated by using SVD-LMMSE estimator, and the channel frequency responses of data tones are interpolated by linear based interpolation method is appropriate for the downlink of 3GPP LTE systems.

8

Session 1B-1: RCF, Propagation Environment & Neural Network Saturday AM, March 17, 2012, Room B

Chair: Kosai RAOOF; Co-chair: Mahmoud AMMAR

25 Model Checking Techniques for Verification of an Encryption Scheme for Wireless Sensor

Networks

Zohra Sbaï and Mohamed Escheikh

Abstract : In this paper, we deal with the formal verification of an encryption scheme for Wireless Sensor Networks (WSNs). Especially, we present our first results on building a framework dedicated to modelling and verification of WSNs aspects. To achieve our goal, we propose to specify WSNs models written in Petri nets using Promela constructs in order to verify correctness properties of them using SPIN Model checker. We first specify in Promela a Petri net description of an encryption scheme for WSNs that describes its behavior. Then, correctness properties that expressrequirements on the system’s behavior are formulated in Linear Temporal Logic (LTL). Finally, SPIN model checker is used to check if a specific correctness property holds for the model, and, if not, to provide a counterexample: a computation that does not satisfy this property. This counterexample will help to detect the source of the eventual problem and to correct it.

41 Simulation of Polarization Strategies of Multiple Antennas System over Rich Scattering

Environment Using the Von Mises Distribution

Maha Ben Zid

Abstract : The aim of this paper is to present a comparative study of polarization strategies of multiple antennas systems over a realistic propagation environnement with rich scatterers. We investigate the von Mises distribution for the analysis of the capacity of the communication systems with different polarizations. We demonstrate in this paper that the polarization strategy that performs better still depends on the distribution characterizing the scattering phenomena within the propagation environment.

48 Performance Analysis of Neural Network Compensator for MIMO-STBC System in Presence

of HPA Nonlinearity and Channel Estimation Error

Oussama Ben Hadj Belkacem,

Ammari Mohammed Lassaad, Rafik

Zayani and Ridha Bouallegue

Abstract :

In order to provide high data rate over wireless channels and improve the system capacity, Multiple-Input Multiple-Output (MIMO) wireless

communication systems exploit spatial diversity by using multiple transmit and receive antennas. Maximal Ratio Combining (MRC) detection is a

simple and effective combiner technique for retrieving multiple transmitted data streams at the receiver. However the detection requires

knowledge of the Channel State Information (CSI) and in practice accurate CSI may not be available. Moreover, to achieve high date rate and

fulfill the power, MIMO systems are equipped with High Power Amplifiers (HPAs).

However, HPAs cause nonlinear distortions and affect the receiver’s performance. Since a few decades, Neural Networks (NN) have shown

excellent performances in solving complex problems (like classification, recognition, approximation). In this paper, we investigate the effect of

9

channel estimation error on the performance of MIMO Space-Time Block Coding (STBC) receiver in the presence of nonlinear HPAs and NN.

By modeling the estimation error as independent complex Gaussian random variables, we assess the impact of HPA nonlinearity and NN on the

SNR derivation and the Symbol Error Rate (SER) in uncorrelated Rayleigh fading channels. Computer simulation results confirm the accuracy

and validity of our proposed analytical approach.

10

Session 2A-2: Wave Structures Saturday AM, March 17, 2012, Room A

Chair: Ali GHARSALLAH; Co-chair: Jamel BELHAJ TAHAR

44 Applying Renormalization Group to Multi-modal Surface Impedance Operator for

Diffraction Analysis

Taha Ben Salah, Chiraz Aguili and

Taoufik Aguili

Abstract :

In this paper we discuss a new accurate method for analyzing diffraction of a fractal shaped structure ad infinite iteration using a combination of

the Renormalization Group Theory and the Multi-modal surface impedance Operator. This new approach helps calculating input impedance of

the structure where no other method pretends being able to provide a concrete characterization of such infinitely complex multi-scale structure.

53 New Tunable Phase Shifter Using Loaded Stepped Impedance Structure Mohamed Ould Elhassen, Mohamed


Ghazel

Abstract :

This paper presents a stepped impedance tunable phase shifter. We give the design of stepped impedance low-pass filter having a maximally flat

response and cutoff frequency of 2.4GHz. In order to tune our circuit characteristics and to modify to insertion phase, we use a varactor diode;

good phase dynamic was obtained with good insertion and return loss

56 Tunable Coupled Line Phase Shifter based on Modified Schiffman Approach Mohamed Ould Elhassen, Mohamed


Ghazel

Abstract :

This paper describes theoretical study, modeling and simulation of tunable coupled line phase shifter. This structure is based on Schiffman model

in which a coupled uniform Microstrip transmission line was used. The main idea of this work is to design a mixed structure tunable phase shifter

using Schiffman model loaded by Varactor diode. We have evaluated the performance of two circuits; a good variation of phase shifting is

denoted with high performances.



11

Session 2B-2: UWB Saturday AM, March 17, 2012, Room B

Chair: Noureddine HAMDI; Co-chair: Tan-Hoa VUONG

26 Design of Tracking Loop for UWB Systems Rshdee Alhakim, Kosai Raoof and

Emmanuel Simeu

Abstract :

Timing synchronization and tracking represent major challenges in carrying out highly efficient Ultra-WideBand (UWB) communications. The

Delay-Locked Loop (DLL) method is widely proposed to maintain satisfactory synchronization. In this paper, we suggest a novel DLL structure

design for UWB systems based on an approach called Timing with Dirty Template. This approach promises to improve tracking performance

while maintaining low-complexity structure. The parameters of the proposed DLL will be selected to optimize tracking behavior in the presence

of the ambient noise and Doppler effects. Simulation results show noise and transient performance across various parameter values.

52 The Tumor Detection by the UWB Radar Elmissaoui Taoufik and Ridha

Bouallegue

Abstract :

The UWB system in medicine consists of sending electromagnetic waves and analyzing the echo in order to create an image of each layer that

composes the human body. In this paper, we propose a new method which enables us to detect and locate a tumor in the human body. In fact, we

study the electric characteristics of each normal human body layer. Similarly, we present the echo reflected by a normal layer and a layer that

contains cancer. These echoes permit our radar system to detect and locate cancer in each region in the human body. Our system enables doctors

to detect cancer at first stage and that facilitates the treatments.

55 A 60-GHz CPW-Fed Antenna for WPAN Applications Zied Harouni, Lotfi Osman, Amel

Fatnassi and Ali Gharsallah

Abstract : An efficient 60 GHz coplanar waveguide (CPW) fed patch antenna is proposed. This antenna is implemented on a high dielectric constant substrate (εr = 9.9), which is close to the dielectric constant of commercial GaAs and CMOS process. The antenna structure combines the advantages of CPW with those of the aperture-coupled microstrip antenna and simplifies the structure of the antenna by reducing the number of metallization level, from three down to two. This feed design eliminates the competition for surface space between the antenna elements and the feed network.








12

Session 2A-3: Codage & MIMO Saturday PM, March 17, 2012, Room A

Chair: Safya BELGHITH; Co-chair: Adnane CHERIF

14 Integration of LDPC codes in MIMO systems Sana Ezzine, Ons Ben Rhouma and

Ammar Bouallegue

Abstract :

Wireless channels are subject to physical constraints responsible for several types of disturbances : noise, fading, multipath propagation,

interference, etc. So it is beneficial to use multiple-antenna systems which are very efficient to reduce the impact of these problems on the

performance of communication system. Furthermore, LDPC codes are error-correcting codes that provide exceptional performance in terms of bit

error probability. We refer to MIMO-LDPC system, the MIMO systems which the LDPC code have been applied.

This paper treats the integration of LDPC codes in MIMO system. For that, we will analyze the performance in terms of bit error rate of multi-

antenna systems by integrating the irregular LDPC codes in those systems according to various parameters such as the number of iterations in

decoding, the number of transmitting antennas, the number of receiving antennas and the length of the LDPC code.We show that the MIMO-

LDPC can achieve the good error rate performance with increased number of iterations in decoding, the number of transmitting antennas and the

number of receiving antennas. We also show that the increase of length LDPC codes does not affect error rate performance.

16 Coded modulations for space-time codes Houda Sboui, Ammar Bouallegue and

Patrick Solé

Abstract :

In this paper, we focus on the case of quasistatic MIMO fading channels when we use concatenated coding schemes. We concatenate tow codes :

an inner code which guarantees full diversity and an outer code which ensures coding gain. An outer code can be designed by taking the quotient

of the algebra by a two-sided ideal which leads to matrices over finite alphabets for the outer code. We present coded modulation schemes for

algebraic space-time codes having the Golden code as inner code.

For the outer code, we begin by studying codes constructions over the finite rings Mn(F3) and Mn(F2) and then we give their multilevels

encoders for these rings.

46 quantum convolutional codes Anis Mahmoudi and Ammar

Bouallegue

Abstract :

The main purpose of this paper is to present a theory of quantum serial turbo codes and describe their iterative decoding algorithm with a

depolarization channel. We define a quantum analogue of a state diagram that provides an efficient way to verify the properties of a quantum

convolutional code, and in particular, its recursiveness and the presence of catastrophic error propagation.

In our constructions, the convolutional codes have thus been chosen to be noncatastrophic and nonrecursive. While the resulting families of turbo

13

codes have bounded minimum distance, from a pragmatic point of view, the effective minimum distances of the codes that we have simulated are

large enough not to degrade the iterative decoding performance up to reasonable word error rates and block sizes.With well-chosen constituent

convolutional codes, we observe an important reduction of the word error rate as the code length increases.

14

Session 2B-3: UWB & RFID Saturday PM, March 17, 2012, Room B

Chair: Fethi CHOUBANI; Co-chair: Khaled GRAYAA

10 Impact of timing mismatch on the performance of a differential receiver Karima Ben Hamida El Abri and

Ammar Bouallègue

Abstract :

This paper studies the influence of timing error on the BER (Bit Error Rate) performance of a DS-UWB (direct sequence ultra wide-band) system.

Through simulation, we show that the reception quality of an UWB system remains good if the error doesn't exceed $3.T_\omega$.

Beyond this value, we constate a degradation of the system performance.

15 Inkjet-Printed rectangular with elements parasitic monopole antenna for RFID applications. Sabri Beldi, Rachida Bedira and Ali

Gharsallah

Abstract :

In this paper inkjet-printed antenna on paper based substrates as solution for the mass production of ultra-low cost Radio Frequency Identification

(RFID). As the growing interest for law cost, flexible, efficient electronics for automatic identification and sensing application increase materials

and integration technique become more complexes.

45 A Broadband Antenna for Passive UHF RFID Tags Mondher Dhaouadi and Mohamed

Mabrouk

Abstract :

A broadband antenna for passive UHF RFID Tag is presented. The reactance component of tag antenna considered chip impedance (-193j) is

conjugated and matched for maximum power transmission. The antenna is fabricated by using Polyester (PET) dielectric substrate with

permittivity 3.2. The size of antenna is 85 × 22 × 0.05 mm. The HFSS simulator is used for optimizing the proposed antenna. The antenna Return

Loss is of 14.0 dB for the worst case in the middle of UHF range, better than 35.3 dB at 914 MHz.

15

Session 2A-4: Complex systems, Localization and Metamaterial Antennas Saturday PM, March 17, 2012, Room A

Chair: Kosai RAOOF ; Co-chair: Larbi HADJ SLAMA

7 Using fuzzy cognitive maps for the modeling of complex systems Farid Lassoued and Ridha Bouallegue

Abstract :

The fuzzy cognitive maps are qualitative tools which can capture the extent from cause to effect in the links that exist within a complex system

such as the information system. These cognitive maps are a simple way of representing knowledge with a huge capacity of interpreting the

information. Indeed, they are exploited for the decision-making, the prediction of future states and the explanation of past actions. Added to these

capacities, when the information is applied and propagated through the model, the topology of the map itself can be used in the diagnosis of

breakdowns by identifying the causes of the nodes of interest.

The main objective of this paper is the conception of impact analysis of engine of rules in an environment object in which objects and their links

of impact (CIs: elementary components of the information system contributing to the delivery of a service), are neither defined nor ordered and

the real time restoration of the results analysis of impact and presentation according to the various orchestrated processes. Thus our role is to

conceive a design of impact analysis and its development guaranteeing in times of answer by using the inference of the fuzzy cognitive maps.

30 A Tri-Band Zeroth-Order Metamaterial-Loaded Monopole Antenna for ISM Applications Nabil Dakhli, Mohamed

Hayouni, Fethi Choubani and Jacques

David

Abstract : The ISM protocol has already been used for a long time to realize customer-specific communication solutions for short and middle distances, which ensure an efficient data transfer, a better reliability and good adaptation for applications which require a low rate of data transfer. The objective of this work is to design a tri-band low-profile small-footprint antenna, which supports the European 434 MHz/868 MHz and the US 315 MHz ISM bands. The radiation mechanism of the antenna is based on the posts, which are connected in series to an inductor at each edge of a transmission line in between. Calibrating the flowing currents in the vias by tuning the inductances values, radiated fields are constructive in the far field region. Full-wave simulations were carried in order to study the properties of the antenna at three different frequencies. The antenna offers a fractional bandwidth of 0.59 %, 0.87% and 2.18%, a radiation efficiency of 12.54%, 38.66% and 77.36% at 315 MHz, 434 MHz and 868 MHz respectively, also a fully omnidirectional, vertically polarized, monopole-like radiation patterns are observed at each band.

38 Indoor Localization using Fingerprinting Technique and Local Linear Estimator Nadia Aloui, Ammar Bouallegue and

Kosai Raoof

Abstract :

In Line-Of-Sight (LOS) environment and Non-Line-Of-Sight (NLOS) circumstances, range-based algorithms such as lateration may fail to offer

good localization accuracy. Therefore, fingerprinting technique is preferred. In this paper, we propose a fingerprinting localization scheme based

on Time Of Arrival (TOA). The estimated TOA is determined by the instant of the maximum cross correlation between the received signal and





16

the source signal. The main contribution of this paper is to apply the kernel linear estimator as a matching algorithm. The simulation results have

shown that the novel localization scheme estimates location within 0.24 m accuracy and 70% precision. Compared to existent algorithms, namely

lateration, nearest neighbor and 4-nearest neighbors algorithms,the proposed scheme brings better performance.

17

Session 2B-4: Acoustic Model; Wavelet; Arabic Speech Saturday PM, March 17, 2012, Room B

Chair: Monia TOURKI; Co-chair: Tahar EZZEDINE

19 Arabic Speech Recognition by Stationary Bionic Wavelet Transform and MFCC using a

Multi Layer Perceptron for Voice Control

Talbi Mourad, Bennasr Mouhamed

and Cherif Adnane

Abstract :

In this paper, we have proposed a new technique of Arabic speech recognition with mono-locutor and a reduced vocabulary. This technique

consists at first step in using our proper speech database containing Arabic speech words which are recorded by a mono-locutor for a voice

command. The second step consists in features extraction from those recorded words. The third step consists in classifying those extracted

features. The features extraction is performed by applying the Stationary Bionic Wavelet Transform (SBWT) to each recorded word at first, the

Mel Frequency Cepstral Coefficients (MFCCs) are computed from the vector obtained from the concatenation of the obtained Stationary Bionic

Wavelet Coefficients. The obtained MFCCs were then concatenated in order to construct one input of a Multi-Layer Perceptual (MLP) used for

features classification. In the MLP learning and test phases, we have used ten Arabic words each of them was repeated twenty five times by the

same ocator. A simulation program used to test the performance of the proposed technique showed a classification rate equals to 98%.

40 Evaluation of an Acoustic Model for Cochlear Implants Based on Frequency Estimation Mourad Ghrissi and Adnen Cherif

Abstract :

Most speech processing strategies in cochlear implants encode only coarse spectral features of the speech signal because of the limited number of

physical electrodes inserted in the cochlea. Some new strategies aim to increase notably the spectral resolution by implementing virtual channels

in order to encode more accurately spectral cues like formant transitions. A new acoustic model for such speech processing strategies is presented

in this paper. It is based on instantaneous frequency estimation within each output of the filter bank. Besides the selection of the frequency bands

used in the stimulation stage is different from previous methods as it is based on the values of the estimated frequencies. Objective analysis of

acoustic models showed that the new strategy encoded more accurately formant transitions when compared to the classic CIS strategy. A

subjective analysis with normal hearing listeners showed that using this strategy yielded to better performance in terms of vowels and consonants

identification when compared to the CIS strategy.

54 OPTIMAL LIFTING BLOCK FOR WAVELET-BASED VIDEO CODING Nabil Chaabani, Tahar Ezzedine and

Ammar Bouallègue

Abstract :

Motion-compensated lifting scheme have become a reference for the temporal filtering of video data. However, blockbased motion estimation and

compensation produce annoying blocking artifacts around the moving objects and near the borders of the images.

In this paper, in the foreground, we will recognize the concept of lifting scheme in general, and then we will give a brief outline on the temporal

lifting scheme of Secker and Taubman, we'll finally explained the method of lifting scheme oriented region where there is a proposed lifting

transformation algorithm in wavelet and justifying the choice of the parameters used.

18

Session 3A-1: Protocols Sunday AM, March 18, 2012, Room A

Chair: Mounir FRIKHA; Co-chair: Kaouther SETHOM

9 Integrating Service Discovery with Reactive Routing Protocol for Mobile Ad Hoc Network Maher Heni and Ridha Bouallegue

Abstract : Mobile ad-hoc networks have a very high increase in academic and industrials areas, and open several research challenges. Results of these challenges are nodes resources that present a critical factor. One of the contributions of ad-hoc networks is that any node can use a service provided by any node in the network and through the multi-hop. This procedure is known as the discovery service. Service is defined as the entity may be a software or hardware that can be used by a user network. To provide these features and meet the requirement to reduce the consumption of critical factors, the aim of this paper is to propose a reliable solution for service data exchange provided by various nodes in the wireless ad-hoc networks and integrate it with a reactive routing protocol. The integration of service discovery with routing protocol present the advantage of running just one layer instead of two and then minimize the waste of resources.

21 Performance of a reconciliation method operating on a discreet quantum key distribution

system

Nedra Benletaief, Houria Rezig and

Ammar Bouallegue

Abstract :

Reconciliation is a mechanism allowing to weed out the discrepancies between two correlated variables. It has great role in every Quantum Key

Distribution protocol where the key has to be transmitted through a noisy channel or as in our case of study in presence of an eavesdropping. In

this paper, we show that for discrete-variable QKD protocols, this problem can be advantageously solved with Turbo codes. In particular, we

demonstrate that our method leads to a significant improvement of Bit Error Rate, may divide it by three in presence of a eavesdropper even with

great eavesdropping capability.

29 Call Admission Control in IEEE 802.16 : Comprehensive Survey and Taxonomy Ahlem Saddoud and Lamia Chaari

Abstract :

WiMAX (worldwide Interoperability for Microwave Access) is the next step in the mobile technology evolution path. It competes with IEEE

802.11-based WLAN technology, broadband residential Internet technologies and third generation cellular technologies. Quality of service (QoS)

is still an important subject that deals with the WiMAX performance. WiMAX can provide QoS guarantees for different service classes with

diverse QoS requirements. Call Admission Control (CAC) is an important QoS component in WiMAX networks as it has a strong relationship

with QoS parameters such as delay, dropping probabilities, jitter and scalability … The IEEE 802.16 standard does not define any CAC scheme

so it is still an open issue for researchers and service providers. The purpose of this paper is to provide a survey on CAC mechanisms in WiMAX

networks. We give an understanding of the different technical issues of CAC approaches that researchers are currently facing to ensure QoS

support in IEEE 802.16 wireless networks. We provide an insight into the new research interest in this field, we classify, and we compare diverse

CAC schemes proposed in the literature.



19

Session 3B-1: Wave Numerical Methods Sunday AM, March 18, 2012, Room B

Chair: Houria REZIG ; Co-chair: Lotfi OSMAN

13 New modal analysis to decompose central arbitrary located source in Planar Almost Periodic

Structures

Bilel Hamdi and Taoufik Aguili

Abstract : In this paper, we provide an effecient new spectral analysis which is important to study a 1-D periodic phased array planar structure excited by arbitrary located sources.The latest demands an accurate evaluation to analyze the modal input impedance in one unit cell with the proper current density appearing on the metal part. The formulation that is proposed to solve the problem allows to study all neighbouring elements in a periodic environment. A Method-of –Moment (MoM) technique based on a simulation code is presented for the analysis of the basic cell (unit cell)

23 Electromagnetic Scattering of a Dielectric Coated Conducting Elliptic Cylinders using WCIP

Method

Jamila Selmi, Rachida Redira and Ali

Garsallah

Abstract :

The problem of scattering of an incident plane wave by metallic and covered objects of arbitrary shape has attracted considerable attention in

telecommunication, antenna design, and electromagnetic compatibility for decades. Many techniques have been proposed to solve the problem of

electromagnetic wave, such as the Moment Method (MOM) and the Finite Element Method (FEM).In this work, the Wave Concept Iterative

Process (WCIP) has been presented and applied to analyse the electromagnetic scattering problems of arbitrary shape bodies. This particular study

was inspired by work to analyse electromagnetic scattering of conductor elliptic cylinder covered with thin dielectric material in free space.

The elliptic cylinders are used to approximately model several real structures, such as aircraft, fuse large and other cylindrical bodies. These

elliptic surfaces can be divided in the small cells, theses cells can be placed on fictitious circular cylinder, so the electromagnetic problem in the

cylindrical coordinates system can be resolved.

Numerical results illustrate the scattering current density and Radar Cross Section (RCS) for different size of a metallic elliptic cylinder, and for

different materials.

43 Numerically Efficient Mode Selection Technique for MoM based Diffraction Analysis Taha Ben Salah, Chiraz Aguili and

Taoufik Aguili

Abstract :

This paper discusses a numerical optimization technique based on mode functions selection for fastening MoM EM analysis of planar obstacles

placed in an infinite waveguide. This technique pretends to give acceptable results while enhancing significantly calculation performance.

Particularly, results for the technique's application on a planar Cantor shaped abstacle are provided



20

Session 3A-2: Channel Estimation & Fuzzy Complex Structures Sunday AM, March 18, 2012, Room A

Chair: Abdellaziz SAMET; Co-chair: Rafik ZAYANI

4 Performance Evaluation of Modified Alamouti Decoding in DVB-T2 Systems using Practical

Channel Estimation

Aymen Omri, Ali Hazmi, Ridha

Hamila and Ridha Bouallegue

Abstract :

In this paper, we present a performance evaluation of an enhanced Alamouti space frequency block decoding scheme for multiple-input multiple-

output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over estimated highly frequency selective channels. This method

uses the variation of the channel frequency response between each consecutive subcarriers to adapt the Alamouti decoder. Simulation results of

DVB-T2 system confirm that this contribution has a good performance in terms of bit error rate when compared to standard Alamouti decoder

over known and estimated highly frequency-selective channels such as single frequency network (SFN) channels.

5 Improving the WCIP method by the contour detection technique and analysis of complex

structures

Hrizi Hafedh

Abstract :

The wave concept iterative procedure (WCIP) is used to analyze high frequency electronic circuits. It is based on the concept of waves in the

place of electromagnetic fields. To study the electronic circuits having complex structures, this method requires much time. In this paper, we

improve the convergence of the WCIP method by adding a new algorithm based on the technique of image contour detection. That’s why the

structure of the studied circuit is considered as an image. The objective is to reduce computing time by reducing dimensions of the calculation

matrices. The reduced matrices are built containing only the important part of the information. Our goal is to prove that the most important zones

in the structure are located in the contour with small steps in the vicinity of the contour.

21

Session 3B-2: Hardware Implantation Sunday AM, March 18, 2012, Room B

Chair: Rached Tourki; Co-chair: Singh SANJEEV

58 Simple power analysis attack on smart card Noura Benhadjyoussef and Hassen

Mestiri

Abstract :

Smart cards are small, portable and tamper-resistant computers. Their uses include security applications ranging from identification and access

control to payment systems and wireless communication framework. A secure smart card has to assurance that secret data like cryptographic key

cannot be recovered or modified by an attacked entity. The purpose of this paper is the implementation of an authentication protocol on smart

card and the analysis of the consumption of this protocol by the Simple Power Attack techniques. (SPA)

59 Implementation of Secured AES Design in CMOS Technology Hassen Mestiri, Noura

Benhadjyoussef and Mohsen

Machhout

Abstract :

The Advanced Encryption Standard (AES) has been thoroughly studied by designers with the goal to improve the performances of the AES

encryption design in terms of area, frequency and power consumption. In this paper, we present the implementation details of the AES encryption

128-bit and the SubBytes transformation. The SubBytes transformation can be implemented using composite field arithmetic in GF((24)2),

GF(((22)2)2) and a multi-stage PPRM architecture. The AES algorithm is implemented using 0.18μm 1.8V Complementary Metal Oxide

Semiconductor (CMOS) technology. A low power consumption of 24.92 μW at 10 MHz was achieved for multi-stage PPRM architecture for

SubBytes transformation.

61 A Hardware implementation of AES-128 on Virtex-5 FPGAs based on different Subbyte

architecture

Nahed Aouf, Mohsen Machhout and

Rached Tourki

Abstract :

One of the best existing symmetric security algorithms is the Advanced Encryption Standard (AES). The three major optimization goals are:

frequency, power consumption and occupation. In this paper we implement an AES pipelined architecture on a single chip of Xilinx Virtex-

5(XC5VLX50FFG676-1) FPGA. Also, we compare three different kind of SubByte implementations as known: the look up table (LUT), GF

(24)2 finite field decomposition and the Positive Polarity Reed-Muller (PPRM), in order to choose the best architecture.

22

Poster Session Session 1

Friday March 16 , 2012 Chair: Hatem BOUJEMAA Co-chair: Fethi TLILI

3 Performance Analysis of a Reactive Routing Protocol for Mobile Ad hoc Networks Maher Heni and Ridha Bouallegue

Abstract : Actually there are much increasing research interest in routing protocols for Mobile Ad Hoc Networks (MANET). This interest is the result of the aim to optimize resource consumption, since they present a critical factor in ad-hoc networks. Works on these protocols focus on protocols behavior modification and performances evaluation in order to reduce consumption of resources. The aim of this work is to evaluate the performances of a reactive routing protocol over mobile Ad hoc Networks called AODV. Computer simulation results show the efficiency of the method and also offer performance measures that agree with competitive methods. The study is conducted over various network topologies and also various terminals mobility mode. In addition various metrics are used for this performance measure mainly: End-to-End Delay, Packet loss, Packet Delivery Ratio and Routing Overhead metric. We also show the robustness of AODV against the terminals mobility and the network size.

6 Possibilistic Localization of Mobile Source Khaoula Baabou, Souhir Fterich and

Hedi Sakli

Abstract :

In order to locate a mobile source in a cellular network, the fusion information is proposed here as an interesting solution to synthesize data. This

approach is increasingly playing an important role in many areas. Many variations are held including the Possibility theory, the subject of our

paper, which we are going to show its use in determining the location of any customer accessing a network. The results would have to properly

reflect these characteristics.

20 Synthesis of Phased Cylindrical Arc Antenna Arrays Using Taguchi Method Amor Smida, Nadhem Nemri, Ridha

Ghayoula and Ali Gharsallah

Abstract :

This paper describes a new approach to synthesize cylindrical antenna arrays controlled by the phase excitation, to synthesize directive lobe based

on Taguchi method. The proposed method is based on iterative minimization of a function that incorporates constraints imposed in each direction.

The results obtained are validated by this method on cylindrical arc Antenna Arrays, which is simulated by CST Microwave.

An 8-element cylindrical arc antenna has been simulated with CST Microwave and tested for various types of beam configurations.

35 Analytical Butterworth-Van Dyke Model of a Ladder BAW Filter Mohamed Ali Boujemaa, Mohamed

Mabrouk and Fethi Choubani

Abstract :

Bulk Acoustic Wave (BAW) filters are specify high Q-factor, high power, integrated RF filters which have proven to be an excellent substitute



23

for conventional RF filters. In this paper, the Butterworth-Van Dyke model is used to model a ladder BAW filter. In order to validate the model,

the analytical results have been compared to the numerical simulation results obtained using the Advanced Design System (ADS). The

comparison shows that the simulation and analytical model's outputs are almost identical.

39 Miniature and Improved Isolation of a 3*3 MMO antennas based on Split Ring Resonator

array

Aouadi Belgacem, Labidi Mondher

and Belhadj Tahar Jamel

Abstract :

In this paper, we study the behavior of a 3*3 Multi-Input Multi-Output (MIMO) antennas like the size and the isolation between the three

radiating elements with and without SRR.

47 Effect of the high impedance surface on the conformal antenna Khaled Jerbi, Mohamed Glaoui and

Ali Gharsallah

Abstract :

we propose to study through this example the influence of high-impedance surface on the inter-element coupling to an conformal antenna. In the

first part, we present the conformal antenna design and its various characteristics. In the second part, we present the properties of and the

geometry of the high impedance surface with vias (Vertical Interconnect Access) that we will use. At the end we will present the architecture of

the antenna with HIS and the result of simulation with CST Microwave and reduced inter-element coupling.

24

Session 2 Saturday March 17 , 2012

Chair: Mohamed SIALA; Co-chair: Sofiane CHERIF

11 A New Scheduling Algorithm For Resource Allocation in LTE Femtocell Networks Kaouthar Sethom, Aicha Ben Salem

and Ridha Bouallegue

Abstract :

Radio Resource Management (RRM) is one of the most challenging and one of the most important aspects of modern wireless communication

networks such as Femtocells. System performance can be improved by applying intelligent radio resource management scheme in wireless

networks. In this paper a new scheduling algorithm based on cooperative game theory is proposed to improve users QoS with respect to its access

priority in LTE Femtocell networks. Each individual user’s goal is to maximize the benefit i.e. the allocated bandwidth

32 Scheduling Schemes Performance Analysis in the LTE-Advanced System with Carrier

Aggregation

Marwane Ben Hcine and Ridha

Bouallègue

Abstract : Carrier Aggregation is the one of the most distinct features of LTE-Advanced. It allows bandwidth extension up to 100 MHz. The use of the appropriate user scheduling scheme assuming different carrier aggregation deployment scenarios is necessary to assure better system performances and optimal use of resources. Assuming carrier aggregation, there are two straightforward scheduling schemes: Separated Random User Scheduling Scheme (SRUS) and Joint User Scheduling Scheme (JUS). First one has simple implementation since it need user equipment to be configured with only one component carrier (CC). The second need user equipment to be configured with multiple component carriers. It is optimal in performance but with high complexity. In this paper, we will study the performance of both scheduling schemes in three deployment scenario: identical coverage, diverse coverage and main beam directed at sector boundaries. The aim of our study is to determine the appropriate scheduling scheme for each deployment scenario. Results show that in diverse coverage ad main beam directed at sector boundaries JUS scheme perform better than SRUS, which can justify the extra control signaling overhead and intensive use of user equipment power. In identical coverage deployment scenario, JUS performances are close to SRUS performances.

60 Blind CFO estimation for OFDM-IDMA system in Rayleigh fading multipath channel Zrelli Yasamine, Houcke Sébastien,

Langlais Charlotte and Ammar

Mahmoud

Abstract :

We address the problem of carrier frequency offset (CFO) in Orthogonal Frequency Division Multiplexing (OFDM) communications systems in

the context of Interleaved Division Multiple Access (IDMA).We propose a technique to adapt a method of blind CFO estimation, called CFO

estimation-Syndrome Function Minimization (C-SFM), to the context of a system combining IDMA and OFDM where a quasi-static Rayleigh

fading multipath channel is considered. Performance in terms of Mean Squared Error (MSE) of carrier frequency offset is studied for a different




25

number of users. In order to evaluate the robustness of the C-SFM method, we compare the performance of OFDM-IDMA system using C-SFM

technique with that of a perfect synchronous system. Our results show that, for high Eb/N0, the two systems have the same performance.

64 Architecture Of Metadata Spatio-Temporal Real-Time For Wireless Sensor Walid Fantazi and Tahar Ezzdine

Abstract :

The information systems containing sensors are more and more used in many applications like the monitoring of the environmental phenomena

(temperature, pressure, humidity, level of CO2, etc). The data gathered by these sensors are space-time data relating to the phenomena observed

thus that the elements to measure. Within the framework of this article we developed an approach for the installation of a communicating space-

time database with an application (Web mapping) which satisfies the needs of users for the management (structuring and the exploitation) of

space-time data within databases sensors. Thus, and according to the data necessary during a time interval and integrated in the database, the

developed interface will make it possible to reach and handle the data, like ordering the operation of the sensors in real-time. This approach will

be applied in the environmental field.

65 Tunable RF Bandpass Filter using Loaded Square Ring Resonator Bousbia Leila and Mohamed Mabrouk

Abstract : In this work, the design procedure, modeling and implementation of reconfigurable filters based on coupled open loop rings resonators is presented. A tunable band-pass filter capable of controlling center frequency bandwidth and selectivity is proposed. The device is tuned by varactor diodes placed at the inner of the open loop ring resonator. Our Simulations show a tunable center frequency range from 2.2GHz to 2.43 GHz, a tunable fractional bandwidth range from 11.36% to 14.81%, and a tunable selectivity range from 0.36 to 0.7.

http://www.easychair.org/utils/wild.cgi?url=http://www.supcom.mincom.tn

26

Session 3 Sunday March 18 , 2012

Chair: Ali HAZMI; Co-chair: Ammar SHARAIHA

8 Novel Timing Acquisition Approach for UWB Systems Moez Hizem and Ridha Bouallegue

Abstract :

In this paper, the goal is to investigate the timing acquisition problem for ultra wideband (UWB) systems using time hopping (TH) spreading.

Low-complexity timing acquisition represents a main challenge to achieve the high potential UWB technology expectations for indoor wireless

communication. For this reason, to address this constraint, we propose and test a new timing acquisition algorithm based on two-stage acquisition

scheme. Applied in [1-4], our algorithm is a combination between coarse synchronization based on timing with dirty templates (TDT) acquisition

scheme and a new fine synchronization algorithm which conduct to an improved estimate of timing offset. We develop this method in both data-

aided (DA) and non-data-aided (NDA) modes. Simulation results show a significant performance improvement in the NDA mode and a small one

in the DA mode. These results are realized in terms of the main square error (MSE) and especially in the acquisition probability, comparing to the

original TDT approach in which the performance degrades to the random symbol effect.

22 Contribution to the optimization of Point-to-Point Systems MIMO Performance with Partial

Channel State Information

Rajoua Anene and Ridha Bouallegue

Abstract :

The main purpose of this paper is to study the performance of the Multiple-input multiple-output (MIMO) wireless communication. MIMO

Systems have the potential to provide high data rates, the evolution of these systems builds upon the ability to furnish high rates with the channel

state information at the transmitter (CSIT), even if obtaining CSIT is a complex task because the resources on the feedback link is very limited.

Therefore, we propose to study the optimization of MIMO wireless communication systems with partial channel state information.

In this paper we propose techniques to exploit the available sources of CSIT in order to optimize the system performance.

Firstly, point-to-point MIMO channels are considered for the aim of error rate minimization.

Secondly linear precoding techniques are proposed to enhance the performance of space-time coded (STC) MIMO systems, based on statistical

information on the MIMO channel.

Computer simulations show that, the performance of such systems can be ameliorates by appropriately combining mean and covariance

information.

33 BER PERFORMANCE OF NEURAL NETWORK COMPENSATOR IN FREQUENCY

DOMAIN BASED MMSE RECEIVER FOR HPA NONLINEARITY IN MIMO OFDM

SYSTEMS

Maha Cherif Dakhli, Rafik Zayani and

Ridha Bouallegue

Abstract :

In this paper, we present a method based on Neural Network (NN) technique in frequency domain and accompanied with MMSE(Minimun Mean

Square Error), which corrects at the receiver level, the Non-linear (NL) distortions due to HPA (Hiqh Power Amplifier). The neural network

27

consists on a feed-forward Multi-Layer Perceptron (MLP) associated with Levenberg)Marquardt learning algorithm. The results show a BER

performance of neural network compensator in frequency domain in a VBLAST MIMO OFDM (Vertical Bell Layered Laboratories Space-Time

Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing) system running under a Rayleigh fading channel.

42 RECEIVER TECHNIQUE FOR THE COMPENSATION OF HPA NONLINEARITY IN

STBC BASED COOPERATIVE AMPLIFY-AND-FORWARD OFDM SYSTEMS

Hela Hizaoui, Rafik Zayani, Ridha

Bouallegue

Abstract :

In this paper, we investigate the effects of high-power amplifier (HPA) nonlinearity on the performance of wireless multiple antenna orthogonal

frequency-division multiplexing (MIMO-OFDM) systems, especially for the Alamouti Space Time Block Coding (STBC) case.

We propose a compensation method for this nonlinearity at the receiver side. The performance of the cooperative STBC-MIMO-OFDM system

equipped with the proposed compensation schema is evaluated in terms of Bit Error Rate (BER) when transmissions are performed over

uncorrelated Rayleigh fading channels. Numerical results are validated by MATLAB simulation and show the high improvements in terms of

BER especially for high SNR values.

49 Mobile Localization Using Channel Impulse Response Fingerprinting And Neural Networks Raida Zouari, Rafik Zayani and Ridha

Bouallegue

Abstract :

In recent years, there has been a growing interest in the mobile network for a variety of interior applications such as the location of people in

confined spaces and underground. Indeed, the location of people, mobile terminals and equipment is most desirable for security and operational

enhancements in mining. Due to the special nature of underground environments, traditional localization techniques based on RSS, AOA, TOA

and TDOA cause in the deterioration of the positioning performance. In this paper, we study a method for mobile localization which combines

Channel Impulse Response (CIR) fingerprinting and Neural Network (NN) techniques.

28

Contact

Takwa BOUALLEGUE

Phone : +(216) 55 40 45 19

e-mail : [email protected]

www.6tel.org / www.innov-com.org

mailto:[email protected]

http://www.6tel.org/

http://www.innov-com.org/

IEEE-International Conference on RFID (IEEE-RFID-2010), 14-16 April 2010, Orlando, Florida (USA)

1/2

Magnetic feeding for UHF-RFID Tags Antenna

(1)M. Dhaouadi, (1)M. Mabrouk, IEEE Member, (2)S. Tedjini, IEEE Senior Member and (1)A. Ghazel, IEEE Senior Member (1)CIRTA’COM, SUPCOM-ISETCOM de Tunis, Cité Technologique des Communications, 2088, Tunisia

Tél. : +216-71-857000, Fax : +216-71-8575555 (1)ORSYS, LCIS, ESISAR-INPG, 50 rue de Laffemas, BP 54, 26902, Valence Cedex 9, France

Tél. : +33-04-75 75 94 00, Fax : +33-04-75 75 94 50 [email protected]

Abstract—In this work, a miniature antenna for a passive UHF RFID tag is designed. A feed structure and matching circuit for an inductively coupling antenna with RFID Tag IC is proposed. The HFSS simulator is used for designing the proposed antenna.

Keywords-UHF-RFID systems; Tag antenna; magnetic coupling;

I. INTRODUCTION The heart of an RFID system is consisting of an emitting antenna (reader) and a tag antenna (receiver). The data transmission between the two antennas is based on inductive coupling. The chip in the tag harvests the RF power transmitted by the reader in order to provide power supply for the chip. The chip uses this power to switch between two impedance states [1, 2]. This change in impedance state modulates the signal backscattered by the RFID Tag antenna and Tag uses this to communicate back to the reader. Three major challenges exist in today’s RFID technologies. The first one is the design of small-size tag antennas with very high efficiency and effective impedance matching for IC chips with typically high capacitive reactance [3]. An inductively coupled feed method is explored to design UHF radio frequency identification tag antennas.

II. INDUCTIVELY COUPLED FEED STRUCTURE A typical inductively coupled feed structure is shown in Fig.1 of [4]. The radiating dipole may be sourced via an inductively coupled small loop placed at a close proximity to the radiating body. The antenna is composed of a small rectangular loop and a radiating (or resonant) body, which are coupled inductively. The terminals of the loop are directly connected to the microchip (Fig.1).

The inductive coupling is modeled by a transformer. The resulting input impedance seen from the loop’s terminals is

[4]: a

loopin ZMfZZ

2...2

Where looploop LfjZ ...2. and aZ are the individual

impedances of the feed loop and the radiating body, respectively. The mutual inductance M also has a relationship with the coupling coefficient K:

aloop LLKM . In this equation, we can see that the coupling factor value is not influenced by the number of turns if the radius of each loop is identical. Only the geometrical antenna shape influences this value. At resonant frequency, the components of antenna input impedance can be predicted as:

aa

in RR

MffR 2

00

)...2()( and loopin LffX ...2)( 00

In this way, the antenna input resistance Rin and input reactance Xin can be adjusted independently, and can be theoretically matched to arbitrary chip impedance. The strength of the coupling, and therefore of the added reactance, is controlled by the distance between the loop and the radiating body as well as by the shape factor of the loop.

III. STRUCTURE AND DESIGN

The geometry of the proposed antenna is shown in Fig. 2.

Fig.2: Structure of Tag antenna with inductively coupled feed

W

L

L1 L2

L3

W1

Equivalent circuit of the radiating body

Equivalent circuit of the feed loop

Chip terminals

aC

inZ

aR

aL

loopL

M

Fig.1: equivalent circuit for RFID tag

IEEE-International Conference on RFID (IEEE-RFID-2010), 14-16 April 2010, Orlando, Florida (USA)

2/2

The tag antenna was small meander dipole on a FR4 substrate (thickness H=0.8mm, relative permittivity r = 4.4 and loss tangent tg ()=0.02. The dimensions of the antenna prototype are Wsub=108mm, Lsub=106.4mm, W=88mm, L=24.7mm, L1=32mm, L2=14, L3=14mm, W1=43mm, as well as the details of the antenna are illustrated in Fig. 2. Integrated chip ASIC Philips (NXP UCODE) enclosed in TSSOP8 body was used for the tag [5]. For maximum power transfer between the tag antenna and the RFID IC, the tag antenna impedance must be the complex conjugate of the RFID IC impedance. The RFID IC impedance is highly capacitive in nature the conjugate match in predominantly inductive. In this paper the antenna is designed for a tag chip with )19322( jZc at a resonant frequency of 866 MHz. The load antenna impedance should be

)19322( jZa for conjugate matching and to transmit the maximum power between the antenna and the microchip. The tag’s design is constructed in such a way that there is no need for extra elements in order to match the antenna input impedance with the chip impedance.

IV. RESULTS The tag antenna is analyzed by the HFSS software; the performances of the antenna are calculated. Fig.3 shows the measured return loss and the impedance against frequency is plotted in Fig. 4.

800.00 850.00 900.00 950.00Freq [MHz]

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

dB(S

(Lum

pPor

t1,L

umpP

ort1

))


m 1

Curve Info


m1 866.6667 -32.1241

Fig.3: Simulated Antenna return loss

800.00 850.00 900.00 950.00Freq [MHz]

0.00

100.00

200.00

300.00

400.00

500.00

Y1


m1

m2

Curve Info



Name X Y

m1 866.6667 12.5672

m2 866.6667 195.0187

Fig.4: Antenna impedance against frequency:

Resistance component aR , Reactance component aX The Voltage Standing Wave Ratio (VSWR) of antenna is another characteristic parameter used to measure the impedance matching of an antenna to its connected load. It is defined as the ratio of the reflected voltage over the incident

voltage. Fig.5 shows that for a VSWR of 0.43dB (1.104), the reflected coefficient is about 26.1 dB and the reflected power is only 5 % of the incident power.

800.00 850.00 900.00 950.00Freq [MHz]

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

dB(V

SW

R(L

umpP

ort1

))


m1

Curve Info


Name X Y

m1 866.6667 0.4303

Fig.5: Antenna VSWR vs. frequency

The current distribution of the antenna is presented in Fig.6

Fig.6: Simulated current distribution at 866.0MHz

V.CONCLUSION The design of new antenna prototype for RFID Tag based on inductively coupling feed is presented. Modeling and simulation results confirm our prediction good performances. Such antennas having these performances are suitable to RFID systems. In the next step, improvements should be carried out in order to reduce the global size of this antenna.

REFERENCES [1] Lindsey, J. F., “Radar Cross-Section Effects Relating to a Horn

Antenna”, IEEE Transactions on Antennas and Propagation, vol. 37, no. 2, pp. 257-260, February 1989


[3] L. Yang, S. Basat, and M. M. Tentzeris, "Design and Development of Novel Inductively Couple RFID Antennas", Procs. of the 2006 IEEE-APS Symposium, pp.1035-1038, Albuquerque, NM, July 2006.

[4] H. W. Son and C.S. Tyo, “Design of RFID tag antennas using an inductively coupled feed”, Electronics Letters, September 2005, pp. 994-996.

[5] UCODE G2XM and UCODE G2XL (TSOOP8 Package Specification) from December 2007, http://www.nxp.com.

UHF Tag antenna for near-field and far-field RFID applications

Abstract— In this paper, a novel broadband Tag antenna for ultra-high frequency (UHF) near-field and far-field radio-frequency identification (RFID) applications is presented. This antenna is printed on an Rogers RT/duroid 5880 substrate with an overall size of 68 × 19.7 × 0.787 mm. The simulated bandwidth of the proposed Tag antenna is more than 100 MHz (860-960MHz), which can cover the entire UHF RFID band. The proposed structure can generate a strong and uniform H-field distribution in the region around the antenna. Measurements show that the antenna operating confirms good performance of Tag identification for near-field and far-field UHF RFID applications.

Keywords-component; Near-field; Far-field; antenna ; Tag

I. INTRODUCTION

In recent years, significant research has been conducted in the area of UHF near-field and far-field RFID communications. RFID technology has gained popularity for a variety of applications such as medical products, pharmaceutical logistics, vehicle security, metro tickets, and contact-less payment. In an UHF RFID system, the reader emits electromagnetic waves through reader antennas. The Tag was placed at different distances from the reader antenna, spanning both near and far field regions. The Tag must be located in the reading area of the reader antenna. The interrogation signal of the reader must have enough power to activate the chip to perform data processing, and transmit back a modulated signal for respond to the reader [1]. Currently, near field UHF RFID receives a lot of attention as a possible solution for item level tagging. The basic near field UHF RFID concept is to make UHF RFID system work at short distances and on different objects as reliably as LF/HF RFID. In most of the near field RFID applications, the interaction between the RFID reader and tags is based on inductive coupling [2]. It appears today that one of the limitations of RFID systems is that they do not operate at short distances (near field). This can be urgently-analyzed to invent antennas for UHF near-field RFID applications. To overcome this problem, some work has been reported to address the design of antennas reader and Tag for near-field RFID applications. For example, in [3], the author proposed a novel RFID reader antenna for simultaneous near-field and far-field operations at UHF band (865-868 MHz). In [4], a broadband segmented loop antenna was proposed for UHF near-field

RFID applications. However, there are only a few papers about the performance of RFID Tag antennas, especially in the aspects of compact size and broadband UHF near-field RFID applications. For example, in [5], two compact near field UHF Tag antennas with a Split Ring Resonator (SRR) structure was proposed for UHF near-field RFID application, but these antennas have low far-field gain (-4 dB) and narrow bandwidth (13 MHz). In this paper, we propose a Tag antenna for near-field and far-field RFID applications. The proposed antenna achieves good impedance matching and uniform magnetic field distribution in the region near the antenna. An EM solver, HFSSTM, is employed to analyze the near field characteristics of the Tag antenna. Design details, simulated and measured results, and a fabricated prototype are presented below.

II. UHF NEAR-FIELD RFID Near-field RFID systems are short range systems based

on inductive coupling between the reader and the Tag antennas. Inductive coupling systems are preferred in most of the applications because the reactive energy is stored in the magnetic field. Such systems are only affected by the objects with high magnetic permeability and are able to operate in close proximity to metal and liquid.

In order to successfully design a near-field UHF RFID system, it is important to investigate the antenna coupling between reader and Tag. If the Tag antenna is small, the magnetic field generated by the reader antenna is hardly perturbed by the tag, and the coupling coefficient is proportional to [2, 6]:

α2222 BSNfC TagTag∝ (1)

where f is the frequency, TagN is the number of turns of the

coil Tag antenna, TagS is the cross-section area of the coil,

B is magnetic field density at the tag location created by the reader antenna, and α is the antenna misalignment loss.

Formula (1) indicates that the coupling in a near-field RFID system with a coil tag is dependent on the magnetic field density generated by the RFID reader antenna. Also, the coupling between the tag and the reader depends of turns of the coil Tag antenna. The design of the RFID Tag antenna has a great influence on conservation or improvement of the magnetic field. The magnetic field is related to the number of turns, diameter, shape and length of the antenna Tag. A Tag antenna with a strong magnetic field allows improve the

M. Dhaouadi1, M. Mabrouk1, Member, IEEE, T.P. Vuong2, Senior Member, IEEE , A.C. de Souza2, andA. Ghazel1, Senior Member, IEEE

1 GRESCOM Lab, SUPCOM, University of Carthage, Tunisia E-mail: [email protected]; [email protected]

2 IMEP-LAHC - UMR 5130, CNRS-INPG-UJF, Minatec-3, Grenoble Cedex 1, France

978-1-4799-4608-2 / $31.00 ©2014 IEEE

magnetic coupling and the reliability of near field communication and is therefore desired in UHF near-field RFID systems.

III. ANTENNA DESIGN

The proposed antenna structure is shown in Fig. 1. The antenna is composed of rectangular feeding loop and a meandered antenna radiating body, which are T-match [7]. The antenna is simulated on an Rogers RT/duroid®

5880 substrate (thickness H=0.787mm, relative dielectric constant 2.2=rε , and loss tangent 009.0tan =δ ) with an overall size of 68 × 19.7 mm2. The antenna parameters are as followings: Lsub = 68 mm, L1 = 20.7 mm, L2 = 17.6 mm, L3 = 6.3 mm, L4 = 4.9 mm, Wsub = 19.7 mm, W1 = 7.6 mm, W2 = 15.7 mm.

Figure 1. Geometry of the proposed antenna

The RFID Tag IC selected for this design is an Alien Higgs-3 RFID IC [8]. The parallel resistance and capacitance of the Higgs-3 chip are 1500 and 0.85 pF, respectively. The return loss of 31.9 dB obtained at the frequency of 880 MHz is shown in Fig. 2.

0,70 0,75 0,80 0,85 0,90 0,95 1,00-34

-32

-30

-28

-26

-24

-22

-20

-18

-16

-14

-12

Ret

urn

Loss

(dB)

Frequency (GHz)

Figure 2. Simulated return loss against frequency for the proposed broadband Tag antenna.

Fig.3 shows the simulated impedance characteristics of the proposed antenna.

0,70 0,75 0,80 0,85 0,90 0,95 1,00

0102030405060708090

100110120130140150160170180

Impe

danc

e (o

hms)

Frequency (GHz)

Imaginary Part of Impedance(ohms) Real Part of Impedance(ohms)

Figure 3. Antenna Impedance Against Frequency: Resistance Component Ra, Reactance Component Xa

The 3-D radiation plot of the antenna is shown in Fig.4.

Figure 4. 3-D far-field radiation plot

IV. FIELD ANALYSIS OF TAG ANTENNA

The technology of near-field UHF RFID has became the target of interest due to the great potentials in RFID applications. The magnetic field intensity generated by RFID Tag antenna should be increased to improve the communication in near-zone applications. The most common UHF Tag antennas for Far Field Communication (FFC) may not perform well in Near Field Communication (NFC). The reduction of the magnetic field produces a distribution of this field which is not uniform for near-field RFID applications. Our proposed Tag structure can produce large currents along the antenna so that a strong magnetic field distribution is excited in the adjacent region around the Tag antenna. Simulations of the surface current and magnetic field distribution of the antenna at 880 MHz are shown in Figs 5a and b, respectively. It is clear that the current is intensive on the meander line of the proposed antenna.

(a) Surface current distribution

(b) Magnetic field distribution

Fig. 5. Simulated near-field characteristics at 880 MHz (z = 0 mm)

V. MEASUREMENTS SETUP

The experimental setup in anechoic chamber is illustrated in Fig. 6. We characterized the performances of the Tag in the near-field and far-field. A mono-static system uses the same reader antenna for both transmitting and receiving. The Tag was placed at different distances from the reader antenna, moving in both near- and far-field regions, and oriented in the direction of maximum gain. We used Agilent E4438C ESG vector signal generator (50 kHz-6 GHz) as transmitter. The reader with the variable power output sends a signal to activate the Tag and decode the data encoded in the chip. This enabled us to determine the minimum reader output power required for active the Tag as a function of frequency. The Tag response is received on HP Agilent 54855A Infiniium oscilloscope.

Figure. 6. Experimental setup of the Tag in the mono-static configuration

A prototype of the antenna was fabricated, as shown in Fig. 7.

Figure. 7. UHF RFID Tag used in measurements

Our antenna is designed to operate well in the far-field, also our proposed antenna demonstrates good performances with inductive coupling for near-field RFID applications. Fig. 8 shows the minimum power necessary for Tag torespond versus frequency in various distances (near-field/far-field) between the Tag and the reader.

860 880 900 920 940 960-14

-12

-10

-8

-6

-4

-2

0

2

4

6

Min

imum

pow

er (d

Bm)

Frequency (MHz)

Far-field measurement (d=65 cm) Near-field measurement (d=18 cm)

Figure. 8. Minimum power vs. frequency for near-field and far-field reading measurements

For near- and far-field reading measurements, our antenna structure has a wide bandwidth (860-960 MHz) for UHF band that covers all frequency bands stated for UHF RFID devices. The minimum power required to read the Tag in the near-zone at 880 MHz is approximately of -12.6 dBm. Measurements show that the reader antenna has a maximum readable range of 18 cm for parallel orientation of our proposed Tag along the positive Z-axis.

VI. CONCLUSION

A novel antenna for passive UHF RFID Tag applications is presented. The broadband Tag antenna performs at near-field and far-field within the worldwide RFID UHF (860–960 MHz) band. The power sensitivity of the Tag was also measured by sweeping the power source and determining the minimum power level required to read the Tag. Such a Tag antenna design is found to be very promising for near-field and far-field UHF RFID applications.

REFERENCES

[1] K. Finkenzeller, “RFID Handbook,” 2nd ed., John Wiley & Sons, 2003.

[2] P. V. Nikitin, K. V. S. Rao, and S. Lazar, “An overview of near field UHF RFID,” in Proc.IEEEInt.Conf.RFID, Mar. 2007, pp. 167–174.

[3] B. Shrestha, A. Elsherbeni, L. Ukkonen, “ UHF RFID Reader Antenna for near-field and far-field operations,” IEEE Antennas Wireless Propag. Lett. , vol.10, Nov.2011, pp. 1274-1277.

[4] X. Qing, C. Khan Goh, Z. Ning Chen, “ A broadband UHF near-field RFID Antenna,” IEEE Trans. Antennas Propag., vol.58,no.12, Dec.2010,pp. 3829-3838.

[5] J. Dong, X. Li, “ UHF Near-Field Tags design based on split ring resonator,” in Proc. APMC, Dec. 2011, pp 1794-1797.

[6] S. Chen, V. Thomas, “Optimization of inductive RFID technology”, IEEE International Symposium on Electronics and the Environment, May 2001, pp. 82 – 87

[7] G. Marrocco,“The art of UHF RFID antenna design : impedance-matching and size-reduction techniques,” IEEE Antennas Propag. Mag., Vo.50, N.1, Jan. 2008, pp. 66-79.

[8] Higgs™ 3 UHF RFID Tag IC, Available: http://www.alientechnology.com/wp-content/uploads/Alien Technology-Higgs-3-ALC-360.pdf .

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Documents

Liste des publications - supcom.mincom.tn · Liste des publications [1] [2] ... [email protected]; mohamed.mabrouk@isetc 130, CNRS-INPG-UJF, Minatec-3, Grenoble Ce RFID reader at