Equalization for Discrete Multitone Transceivers. Güner Arslan Ph.D. Defense Committee Prof. Ross Baldick Prof. Alan C. Bovik Prof. Brian L. Evans, advisor Prof. Joydeep Ghosh Dr. Sayfe Kiaei Prof. Edward J. Powers. Receive bit stream. Transmit bit stream. Transmitter. Channel.
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Equalization for Discrete Multitone Transceivers
Güner Arslan
Ph.D. Defense
Committee
Prof. Ross Baldick
Prof. Alan C. Bovik
Prof. Brian L. Evans, advisor
Prof. Joydeep Ghosh
Dr. Sayfe Kiaei
Prof. Edward J. Powers
Transmit bit stream
Transmitter
Channel
Receiver
TEQ
Outline
Courtesy of Shawn McCaslin (Cicada Semiconductor, Austin, TX)
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Intersymbol Interference (ISI)
=
*
Receivedsignal
Channel
Transmit signal
Threshold
at zero
1
1
1
1
Detected signal
MMSE
Equalizer frequency response
Zeroforcing Equalizer frequency response
Channel frequency response
Magnitude (dB)
Frequency
channel
frequency response
magnitude
carrier
subchannel
frequency
copy
copy
s y m b o l ( i+1)
CP
CP
s y m b o li
CP: Cyclic Prefix
v samples
N samples
N/2 subchannels
N subchannels (N = 512 for ADSL)
DAC and
transmit filter
serial to parallel
QAM
encoder
mirror
data
and
NIFFT
add
cyclic prefix
parallel to serial
TRANSMITTER
channel
RECEIVER
N/2 subchannels
N subchannels
parallel to serial
QAM
decoder
invert channel
=
frequency
domain
equalizer
NFFT
and
remove
mirrored
data
serial
to
parallel
remove
cyclic prefix
receive filter
and
ADC
TEQ
time domain equalizer
rk
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xk
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h
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Minimum Mean Squared Error (MMSE) MethodChow, Cioffi, 1992
h
Maximum Shortening SNR (MSSNR) MethodMelsa, Younce, Rohrs, 1996Maximum Geometric SNR MethodAlDhahir, Cioffi, 1996
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xk
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b
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CP
CP
Contribution #1New Subchannel Model: Motivating ExampleTail
ISI
signal
ISI
noise
1
...
k
Contribution #1Proposed Subchannel SNR Modelnk
rk
yk
xk
h
w
+
xk
h
w
x
Signal
gk
xk
h
w
x
ISI
1gk
nk
w
noise
Sx,i
H
HT
qi
Ai
=
Sn,i
Sx,i
qiH
qiH
H
HT
qi
=
qi
Bi
+
D
GT
G
DT
FT
F
Contribution #2Optimal Maximum Channel Capacity (MCC) TEQTEQ taps
cyclic prefix () 32
FFT size (N) 512
coding gain 4.2 dB
margin 6 dB
input power 14 dBm
noise power 113 dBm/Hz,
crosstalk noise 10 ADSL disturbers
TEQ taps
cyclic prefix () 32
FFT size (N) 512
coding gain 4.2 dB
margin 6 dB
input power 14 dBm
noise power 113 dBm/Hz,
crosstalk noise 10 ADSL disturbers
TEQ taps 17
FFT size (N) 512
coding gain 4.2 dB
margin 6 dB
input power 14 dBm
noise power 113 dBm/Hz,
crosstalk noise 10 ADSL disturbers
TEQ taps 2
FFT size (N) 512
coding gain 4.2 dB
margin 6 dB
input power 14 dBm
noise power 113 dBm/Hz,
crosstalk noise 10 ADSL disturbers
Cyclic prefix length of 32
FFT size (N) 512
Coding gain 4.2 dB
Margin 6 dB
Input power 14 dBm
Noise power 113 dBm/Hz
Crosstalk noise 10 ADSL disturbers
Simulation Results for TwoTap TEQ
Cyclic prefix length of 32
FFT size (N) 512
Coding gain 4.2 dB
Margin 6 dB
Input power 14 dBm
Noise power 113 dBm/Hz
Crosstalk noise 10 ADSL disturbers
ADSL: Asymmetric DSL
CAD: Computer aided design
CP: Cyclic prefix
DAC: Digitalanalog converter
DMT: Discrete multitone
DSL: Digital subscriber line
FFT: Fast Fourier transform
HDSL: Highspeed DSL
IFFT: Inverse FFT
ISDN: Integrated service digital network
ISI: Intersymbol interference
LAN: Local area network
MCC: Maximum channel capacity
MFB: Matched filter bound
minISI: Minimum ISI
MMSE: Minimum MSE
MSE: Mean squared error
MSSNR: Maximum SSNR
QAM: Quadrature amplitude modulation
SNR: Signaltonoise ratio
SSNR: shortening SNR
TEQ: Time domain equalizer
VDSL: Veryhighspeed DSL
Acronyms