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ITU WCRL
Battle of the Waveforms for 5G
GUNES KARABULUT KURT, SELAHATTIN GOKCELI
gkur t@i tu .edu. t r, gokce l i s@i tu .edu. t r
W i re less Communicat ions and Research Laboratory (WCRL)
ISTANBUL TECHNICAL UNIVERSITY
ITU WCRL
OUTLINE
h"p://sine.ni.com/cs/app/doc/p/id/cs-17378#
Introduc;on: OFDM/OFDMA
5GChallenges
WaveformDesignTargets
Implementa;onPrespec;ve:
UniversallyFilteredMul;-carrier(UFMC)Systems
ErrorPerformance&Sidelobelevels
FurtherImprovements
Summary
IEEE 5G GREECE SUMMIT 2
ITU WCRL
OFDM/OFDMA
Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access: Enables transmission of parallel data streams
þ High data rates
þ Robustness to frequency selectivity
ý Sensitivity to time/frequency offsets
ý High peak to average power ratio (PAPR)
ý High sidelobe levels
IEEE 5G GREECE SUMMIT 3
ITU WCRL
5G Challenges Solutions to OFDM/OFDMA problems: ê Spectral efficiency ê Energy efficiency
IEEE 5G GREECE SUMMIT 4
ITU WCRL
5G Challenges Solutions to OFDM/OFDMA problems: ê Spectral efficiency ê Energy efficiency
OFDM/OFDMAmaynotaddress5Gconstraints!
IEEE 5G GREECE SUMMIT 5
ITU WCRL
5G Challenges Solutions to OFDM/OFDMA problems: ê Spectral efficiency ê Energy efficiency
OFDM/OFDMAmaynotaddress5Gconstraints!
Newwaveformsmaybeasolu;on
IEEE 5G GREECE SUMMIT 6
ITU WCRL
Design Targets é Spectral efficiency é Energy efficiency ê PAPR ê Sidelobe levels
+ Simpler synchronization
IEEE 5G GREECE SUMMIT 7
ITU WCRL
Candidate Techniques ü Filter Bank Multicarrier Modulation [SIOHAN, 2002]
ü Generalized Frequency Division Multiplexing [FETTWEIS, 2009]
ü Filtered-OFDM [ABDOLI, 2015]
ü Zero-tail DFT-spread-OFDM [BERARDINELLI, 2013]
ü Universal Filtered Multi-Carrier [VAKILIAN, 2013]
ü …
IEEE 5G GREECE SUMMIT 8
ITU WCRL
Implementation Perspective
A good compromise: UFMC þ Better control of sidelobe levels/interference þ Robustness to syncronization sensitivity:
Carrier Frequency Offset/Timing Offset
IEEE 5G GREECE SUMMIT 9
X1 N1-IDFTFiltering
F1
DACX2 N2-IDFTFiltering
F2
XB NB-IDFTFiltering
FB
.
.
.
.
.
.
Cyclic-Prefix
RemovalADC
Synchronization
Filtering/Channel
Equalization
Estimated Bits2N-DFT
TRANSMITTER
RECEIVER
ITU WCRL
SDR Testbed
IEEE 5G GREECE SUMMIT 10
ITU WCRL
Measurement Results
IEEE 5G GREECE SUMMIT 11
ITU WCRL
Sidelobe levels (1/2)
IEEE 5G GREECE SUMMIT 12
ITU WCRL
Sidelobe levels (2/2)
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
20 32 Subcarriers
OFDMDFT-s-OFDMUFMC
(a)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMDFT-s-OFDMUFMC
(b)
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
2048 Subcarriers
OFDMDFT-s-OFDMUFMC
(c)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMDFT-s-OFDMUFMC
(d)
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
2064 Subcarriers
OFDMDFT-s-OFDMUFMC
(e)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMDFT-s-OFDMUFMC
(f)Figure 5.3 : For 16, 24 and 32 subcarriers, PSD results of UFMC, OFDM and
DFT-s-OFDM are shown at (a), (c) and (e), respectively. Moreover,respective combined PAPR results are shown at (b), (d) and (f).
57
IEEE 5G GREECE SUMMIT 13
ITU WCRL
Further Improvements
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
20 32 Subcarriers
ZP-DFT-s-OFDMZP-DFT-s-UFMC
(a)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMZP-DFT-s-OFDMZP-DFT-s-UFMC
(b)
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
2048 Subcarriers
ZP-DFT-s-OFDMZP-DFT-s-UFMC
(c)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMZP-DFT-s-OFDMZP-DFT-s-UFMC
(d)
Normalized frequency-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
PSD
(dBW
/Hz)
-100
-80
-60
-40
-20
0
2064 Subcarriers
ZP-DFT-s-OFDMZP-DFT-s-UFMC
(e)
CCDF0 1 2 3 4 5 6 7 8 9 10 11
PAPR
(dB)
10-5
10-4
10-3
10-2
10-1
100
OFDMZP-DFT-s-OFDMZP-DFT-s-UFMC
(f)Figure 5.5 : For 16, 24 and 32 subcarriers, PSD results of ZP-DFT-s-UFMC and
ZP-DFT-s-OFDM are shown at (a), (c) and (e), respectively. Moreover,respective combined PAPR results are shown at (b), (d) and (f).
60
X1
M1-DFT
Zero Padding N1-IDFT Filtering
F1
DAC
Precoding
X2
M2-DFT
Zero Padding N2-IDFT Filtering
F2
Precoding
XB
MB-DFT
Zero Padding NB-IDFT Filtering
FB
Precoding
.
.
.
.
.
.
.
.
.
Figure 5.1 : Block diagram of the transmitter implementation.
Figure 5.2 : Block diagram of the receiver implementation.
supported with zero-padding, zeros are added into data symbols in order to implement
ZP-DFT-s-UFMC. This step can be represented as
ui [m] =
(
0, m = 0,1, . . . ,Z �1ui[m], m = Z,Z +1, . . . ,M�1,
(5.1)
where Z is the number of added zero symbols, M is the length of DFT, i = 1,2, . . . ,B is
the index of the subband where total number of subbands is B, ui is the data symbols at
ith subband before the M-DFT operation. Then to complete ZP-DFT-s-UFMC symbol
generation, spreading with DFT-precoding can be implemented. Lets assume that the
output of this operation is Xi[k], where k = 0,1, . . . ,K �1 is the subcarrier index with
total number of subcarriers K. If spreading version of UFMC is not considered, then
weighted correlative coding operation can be applied to Xi[k] as [28]
Xi[k] =p
22
(e jq Xi[k]+Xi[k+1]), k = 1,2, . . . ,K �1, (5.2)
51
TRANSMITTER
Figure 5.1 : Block diagram of the transmitter implementation.
Cyclic-Prefix
RemovalADC
Synchronization
Filtering/Channel
Equalization
Estimated Bits2N-DFT ML
Detection
Figure 5.2 : Block diagram of the receiver implementation.
supported with zero-padding, zeros are added into data symbols in order to implement
ZP-DFT-s-UFMC. This step can be represented as
ui [m] =
(
0, m = 0,1, . . . ,Z �1ui[m], m = Z,Z +1, . . . ,M�1,
(5.1)
where Z is the number of added zero symbols, M is the length of DFT, i = 1,2, . . . ,B is
the index of the subband where total number of subbands is B, ui is the data symbols at
ith subband before the M-DFT operation. Then to complete ZP-DFT-s-UFMC symbol
generation, spreading with DFT-precoding can be implemented. Lets assume that the
output of this operation is Xi[k], where k = 0,1, . . . ,K �1 is the subcarrier index with
total number of subcarriers K. If spreading version of UFMC is not considered, then
weighted correlative coding operation can be applied to Xi[k] as [28]
Xi[k] =p
22
(e jq Xi[k]+Xi[k+1]), k = 1,2, . . . ,K �1, (5.2)
51
RECEIVER
IEEE 5G GREECE SUMMIT 14
ITU WCRL
Summary
1. OFDM&OFDMAareproventechniques2. Densenetworksmayrequiremoreflexiblewaveformdesign
3. UFMCisagoodop;onintermsofitsflexibility
IEEE 5G GREECE SUMMIT 15
ITU WCRL
Selected References:
IEEE 5G GREECE SUMMIT 16
[SIOHAN, 2002] P. Siohan, C. Siclet and N. Lacaille, "Analysis and design of OFDM/OQAM systems based on filterbank theory," in IEEE Transactions on Signal Processing, vol. 50, no. 5, pp. 1170-1183, May 2002. [FETTWEIS, 2009] G. Fettweis, M. Krondorf and S. Bittner, "GFDM - Generalized Frequency Division Multiplexing,” IEEE 69th Vehicular Technology Conference, Barcelona, 2009, pp. 1-4. [ABDOLI, 2015] J. Abdoli, M. Jia and J. Ma, "Filtered OFDM: A new waveform for future wireless systems," 2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Stockholm, 2015, pp. 66-70. [BERARDINELLI, 2013] G. Berardinelli, F. M. L. Tavares, T. B. Sørensen, P. Mogensen and K. Pajukoski, "Zero-tail DFT-spread-OFDM signals," 2013 IEEE Globecom Workshops (GC Wkshps), Atlanta, GA, 2013, pp. 229-234. [VAKILIAN, 2013] V. Vakilian, T. Wild, F. Schaich, S. ten Brink and J. F. Frigon, "Universal-filtered multi-carrier technique for wireless systems beyond LTE," 2013 IEEE Globecom Workshops (GC Wkshps), Atlanta, GA, 2013, pp. 223-228
