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Powerline Communications: Channel Characterization and Modem Design. Yangpo Gao Helsinki University of Technology yangpo.gao@nokia.com 2005-10-18. Thesis Contents. Table of Contents Introduction PLC Technology Background Channel Measurement and Modeling Disturbance over PLC - PowerPoint PPT Presentation
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Powerline Communications:Channel Characterization and Modem Design
Yangpo Gao
Helsinki University of Technology
yangpo.gao@nokia.com 2005-10-18
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design22 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Thesis Contents
Table of ContentsIntroduction
PLC Technology Background
Channel Measurement and Modeling
Disturbance over PLC
DMT Based PLC Modem Design
Conclusion
Reference
This thesis is part of project “ PLC controlled LEDs for general lighting system”, which is sponsored by TEKES
Introduction
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design44 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
History of PLC and Motivation of Thesis
What is PLCPLC – Powerline CommunicationsUsing powerline as transmission medium for data communication
History of PLCFrom high voltage (HV) low voltage (LV)Low data rate high data rateControl application multimedia data applications
MotivationCheap “the last mile” solutionHowever, worse channel than other wired networkChannel characterization reliable communications
PLC Technology Background
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design66 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
PLC Technologies
Three network levelsHigh voltage (110–380 kV) Medium voltage (10–30 kV) Low voltage (230/400 V, in the USA 110 V) (my thesis range)
Efficient couplingInductive couplingConductive coupling
Modulation and error correctionOFDM, DMTCDMAFEC
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design77 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
EMC Issues
EMC --Electromagnetic compatibilityThe ability of a device or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances in the form of interferences to any other system in that environment, even to itself.
Electromagneticcompatibility (EMC)
electromagneticemission (EME)
Electromagneticsusceptibility (EMS)
Conductedemission (CE)
Radiatedemission (RE)
Radiatedsusceptibility (RS)
Conductedsusceptibility (CS)
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design88 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Standardizations
PLC standardization bodies
IEC Committee
TC 77 CISPR Product Committees
ITU ISO CENELECAisa and Pacific
organizations FCCRA RegTP
InternationalInternational
RegionalRegionalNationalNational
Channel Measurement and Modeling
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1010 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Transmission Line Theory
A piece of mains cable can be modeled as following figure
( , )i z tR z
L z
Gz
C z
( , )i z z t
( , )v z t ( , )v z z t
zz z z
R : resistance . L : inductance.G : conductanceC : capacitance
0 0( ) ( ) ( ) z zV z V z V z V e V e
0 0( ) ( ) ( ) z zI z I z I z I e I e
( )( )j R jwL G jwC
00
0
V R jwL R jwLZ
I G jwC G jwC
Attenuationconstant
phaseconstant Characteristic
impedance
Propagationconstant
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1111 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Channel Measurement Setup
Equipment:Network Analyzer (NA)
Coupling Circuit
Coupling circuitConductive coupling
High pass filter
Galvanic isolation
Over Voltage protection
NA
Cou
pler
Cou
pler
PLCchannel
Transmittest head
Receivetest head
C1
C2
D1
D2 D3 D4
D5To
powerl i neTo measurement
devi ce
T1
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1212 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
10-1
100
101
102
-14
-12
-10
-8
-6
-4
-2
0
2
Frequency (MHz)A
tten
uatio
n (d
B)
1. 0.75mm2 Vulcanize rubber cable
2. 1mm2 Vulcanize rubber cable
3. 0.75mm2 PVC/PVC cable
4. 0.5mm2 PVC/PVC cable
Fluctuation at high frequency
(2)
(3)
(1) (4)
• Rapid fluctuation caused by impedance mismatch
• Maximum of 4 dB attenuation difference @ 100 MHz
rR
rR
Cable transversal
PLC Cable Measurements
Cable Type Size (mm2)
Vulcanize rubber cable (three-wire) 0.75
Vulcanize rubber cable (three-wire) 1
PVC/PVC cable (three-wire) 0.75
PVC/PVC cable (two-wire) 0.5
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1313 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
PLC Channel Measurements
Scenario 1: Internet access and distribution
Scenario 2: Home networking
0 20 40 60 80 100-30
-25
-20
-15
-10
-5
0
Frequency (MHz)
Am
plitu
de A
tten
uatio
n (d
B)
1. socket 12. socket 23. socket 34. 20 m cable
(1 )
(2 )
(4)
(3)
Scenario 1: Network topology is known, or easy to estimate. Channel is simple, and
has few multipath components Scenario 2: Network topology is unknown
or it is hard to define. Channel acts as
black box. A lot of multipath components
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1414 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Channel Responses
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8-0.2
-0.1
0
0.1
Time (us)
Am
plitu
de
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
Time (us)
Am
plitu
de
0 20 40 60 80 100-25
-20
-15
-10
-5
0
Frequency (MHz)
Ch
an
ne
l att
en
ua
tion
(d
B)
0 20 40 60 80 100-30
-25
-20
-15
-10
-5
Frequency (MHz)
Ch
an
ne
l att
en
ua
tion
(d
B)
FrequencyDomain
TimeDomain
Scenario 1 Scenario 2
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1515 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
PLC Channel Modeling
According to PLC channel multipath phenomenon, channel can be modeled as:
3hL
2
0g 1g 2g 3ghLg
I nput
Output
. . .
. . .
. . .
. . .
1
1
( ) ( )hL
i ii
h t g t
1
( ) ( )hL
i ii
H f r t
( )( , ) id f l
i ir f l a e 0
1 20
( ) ( ) ( )
2 2
R Gd f d f d f
GZRv f v f
Z
0 1( ) ( )d f c c f
Disturbance over PLC
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1717 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
PLC Noise
Noise Classification:Colored background noise
Narrowband noise
Periodic impulsive noise, asynchronous to the main frequency
Periodic impulsive noise, noise, synchronous to the main frequency
Asynchronous impulsive noise
Our concentrationColored background noise
Asynchronous impulsive noise
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1818 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Noise Measurement setup
Equipment:Oscilloscope
Spectrum Analyzer
Coupler
PLC
chan
nel
Cou
pler
Spectrumanalyzer
(frequency domain)
Oscilloscope(time domain)
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design1919 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Colored Background Noise
Quasi-Static behavior
Statistic information is extracted in table
Can be modeled as:
0 20 40 60 80 100-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
Frequency (MHz)
Bac
kgro
und
Noi
se P
SD
(dB
m)
1. Maximum background noise PSD2. Average background noise PSD3. Minimum background noise PSDCurve fitting
(1) (2)
(3) ( ) 10 (W/Hz)cs b fN f
s b c
Max -94 -80 -0.4
Min -124 -100 -0.6
Average -105 -90 -0.5
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2020 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Random Impulsive Noise
Caused by frequency bursts generated by electrical devices connected to the powerline.
Statistic information is extracted
0 2 4 6 8 10 12 14 16 18 20 -0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
Time (ms)
Impu
lsiv
e no
ise
am
plitu
de (
v)
0 200 400 600 800 1000 1200 1400 1600 1800 2000-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Time (us)
Impu
lsiv
e n
ois
e am
plitu
de
(V)
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2121 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Other Disturbance
NEXT (Near End crosstalk)
FEXT (Far End crosstalk).
ELFEXT FEXT Cable Attenuation
0 20 40 60 80 100-120
-100
-80
-60
-40
-20
0
20
Frequency (MHz)
FE
XT
Att
enua
tion
(dB
)
1. PLC FEXT2. Cable Attenuation3. PLC ELFEXT4. xDSL FEXT
(2)
(1)
(3)
(4)
Transmi t
Recei ve
NEXT
NEXT Formation
FEXT Formation
Transmi t
Recei ve
FEXT
DMT Based PLC Modem Design
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2323 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
DMT Technology
Discrete Multi-tone Modulation (DMT)
Advantages:Multicarrier technology – combat frequency selective fading
Dynamic bit loading based on SNR – efficient spectrum utilization
High channel capacity
EncoderConstel l at i on
mappi ng and Toneshuffl e
I FFTCycl i cprefi x
P/ STransmi tter
fi l ter
DecoderConstel l at i onde-mappi ng andTone shuffl e
FFTCycl i cprefi xremove
S/ PRecei verfi l ter
PLC ChannelNoi se
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2424 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
DMT Based PLC Modem Design
Simulation environment:MATLAB SimuLink
MATLAB DSP Blockset
Simulated channel response
Expected resultBit Error Rate (BER)
0 20 40 60 80 100-30
-25
-20
-15
-10
-5
Att
enua
tion
(dB
)
Frequency (MHz)
Simulated channelMeasured channel
BitSource
AdaptiveLoading
Algorithm
DMTModulator
SpectrumObservation
SpectrumObservation
PLC Channel
NoiseGenerator
DMTDemodulator
BERComparison
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2525 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Simulation and Performance
0 32 64 96 128 160 192 224 2560
5
10
15
Channel Number
Num
ber
of b
its p
er c
hane
l
0 10 20 30 40 5010
-7
10-6
10-5
10-4
10-3
10-2
10-1
100
SNR (dB)
BE
R
DMT over AWGN channelDMT over PLC channel
Optimized bit loading algorithm
Signal spectrum before PLC channel
Signal spectrum after PLC channel
Modem performancePLC vs AWGN
Publications Related to My Thesis
Powerline Communications: Channel Characterization and Modem DesignPowerline Communications: Channel Characterization and Modem Design2727 Yangpo Gao,Yangpo Gao, 2005-10-18 2005-10-18
Publications
More information can be found in my publications:
“Channel modeling and modem design for broadband
power line communications”, Proceeding of ISPLC 2004,
April, Spain
“Broadband characterization of indoor powerline channel”,
Proceeding of ISPLC 2004, April, Spain
“Broadband Characterization of Indoor Powerline Channel
and Its Capacity Consideration”, Proceeding of ICC 2005,
May, Korea
Any Questions?
Thank You!
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