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L40: Lower Power Equalizer. J. W. Kim and J.D.Cho 성균관대학교 http://vada.skku.ac.kr . Low Power Equalizer . Jin Woo Kim, J.D.Cho, 1999, SKKU Introduction Equalizer Low-Power Methodology in Equalizers Simulation Future Work Reference. Introduction – xDSL (Digital Subscriber Line).

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L40 lower power equalizer

L40: Lower Power Equalizer

J. W. Kim and J.D.Cho

성균관대학교

http://vada.skku.ac.kr

SungKyunKwan Univ.


Low power equalizer
Low Power Equalizer

  • Jin Woo Kim, J.D.Cho, 1999, SKKU

  • Introduction

  • Equalizer

  • Low-Power Methodology in Equalizers

  • Simulation

  • Future Work

  • Reference

SungKyunKwan Univ.


Introduction xdsl digital subscriber line
Introduction – xDSL(Digital Subscriber Line)

  • Provide high bandwidth over copper twisted pair local loop cable, without amplifiers or repeaters

  • Utilize full potential of a copper telephone subscriber loop up to a few hundred times that of a voiceband modem

  • Support industry – standard transmission formats and bit rate such as T1 and E1

SungKyunKwan Univ.


Introduction xdsl channel configuration
Introduction – xDSL Channel Configuration

SungKyunKwan Univ.


Dmt for adsl discrete multitone modulation
DMT for ADSL( Discrete MultiTone Modulation)

  • Built-in subchannel optimization

  • Ongoing active monitoring

  • Maximum loop variation coverage

  • Highest level of rate flexibility

  • Superior noise immunity for greater throughput

  • Broad industry chipset support

  • Interoperability through standards

  • Virtually future proof

SungKyunKwan Univ.


Dmt subchannel allocation for adsl
DMT SubChannel Allocation for ADSL

  • #1 ~ #6 : Analog Voice

  • #7 ~ #38 : Upstream Channels

  • #7 ~ #256 : Downstream Channels

SungKyunKwan Univ.


Adsl block diagram dmt
ADSL Block Diagram ( DMT )

SungKyunKwan Univ.


Equalizer teq time domain equalizer
Equalizer – TEQ ( Time Domain Equalizer )

  • TEQ with a small number of taps can reduce the cyclic prefix(CP)

  • Power Consumption Critical Part

  • Adaptive FIR filters (LMS algorithm)

    • The Filter Output

    • The Filter Coefficient

    • The Error Signal

SungKyunKwan Univ.


Equalizer example of teq
Equalizer – Example of TEQ

SungKyunKwan Univ.


Equalizer feq frequency domain equalizer
Equalizer – FEQ ( Frequency Domain Equalizer )

  • Compensate for the remaining frequency dependent attenuation and phase rotation of each subchannel

  • Complex One-Tap FIR filter per one subchannel (ADSL ; 256-7)

SungKyunKwan Univ.


Equalizer example of feq
Equalizer – Example of FEQ

  • LMS(Least Mean Square) Adaptive Filter

SungKyunKwan Univ.


Low power methodology in equalizers circuit
Low Power Methodology in Equalizers – Circuit

  • FIR Filter

    • Carry-save adder

    • Grouped Multipliers(Wallace Tree Multiplier)

    • Booth Recoding technique

  • Updating Circuits

    • Power-of-two LMS updating

    • The use of register file

    • Coefficient freezing

    • Make step size constant(m) to power-of-2

SungKyunKwan Univ.


Low power methodology in equalizers run time
Low Power Methodology in Equalizers – Run-time

  • The Error Monitor

  • Adaptive Bit Precision

  • Burst-Mode Update

  • Adaptive Filter Length

SungKyunKwan Univ.



Simulation environment 1
Simulation – Environment (1)

Input Sequence

PRD(Pseudo Random Sequence)[T1E1.4]

Make 4-QAM symbols as Training Sequence

SungKyunKwan Univ.


Simulation environment 2
Simulation – Environment (2)

  • Test Channel

    • CSA#6

      • 26AWG(0.4mm)

      • 9000ft(about 2.7Km)

    • AWGN noise environment

    • SNR 40dB

SungKyunKwan Univ.


Simulation channel impulse response
Simulation – Channel ( Impulse Response )

SungKyunKwan Univ.


Simulation before training received constellation
Simulation – Before Training( Received constellation )

SungKyunKwan Univ.


Simulation before training coefficient constellation
Simulation – Before Training( Coefficient constellation )

SungKyunKwan Univ.


Simulation before training output constellation
Simulation – Before Training( Output constellation )

SungKyunKwan Univ.


Simulation after training output constellation
Simulation – After Training( Output constellation )

SungKyunKwan Univ.


Simulation output snr
Simulation – Output SNR

SungKyunKwan Univ.


Simulation result analysis
Simulation – Result Analysis

  • Step Constants(m) are power-of-2

    • 0.5 -> ½ (2-1)

    • 0.125 -> 1/8 (2-3)

    • 0.03125 -> 1/32 (2-5)

    • 0.007125 -> 1/128 (2-7)

  • The smaller Constant, the longer convergence time

  • Replace Complex Multiplier to Just Exponent Adder

  • Low Power Consumption is acquired

SungKyunKwan Univ.


Simulation using hp ads schematic transceiver
Simulation – Using HP ADSSchematic - Transceiver

SungKyunKwan Univ.


Simulation using hp ads schematic channel
Simulation – Using HP ADSSchematic - Channel

SungKyunKwan Univ.


Simulation using hp ads schematic receiver
Simulation – Using HP ADSSchematic - Receiver

SungKyunKwan Univ.


Future work 1
Future Work (1)

  • Simulation

    • TEQ simulation

    • NEXT, FEXT Channel Modeling

    • Attach Cyclic Prefix

    • Echo Canceller Simulation

    • Apply more Low-power Method

    • Apply Auto Bit Loading

    • Transmission Test to 215-QAM

SungKyunKwan Univ.


Future work 2
Future Work (2)

  • Hardware Synthesis

    • Implement FEQ in VHDL (Synopsys)

    • Implement TEQ in VHDL (Synopsys)

    • Apply Low-Power algorithm to EQ

    • Verify the function between Classical EQ and Low-Power EQ

    • Compare the power between Classical EQ and Low-Power EQ

SungKyunKwan Univ.


Future work 3
Future Work (3)

  • Current Simulation and Implementation model is for ADSL, but after improve the Speed and Power, I will apply all the algorithms to VDSL.

SungKyunKwan Univ.


Reference 1
Reference (1)

  • W. Y. Chen, “DSL”, Macmillan Technical publishing, 1998

  • W. Goralski, “ADSL and DSL Technologies”, McGraw-Hill, 1998

  • K. Azadet et al, “Low-Power Equalizer Architectures for High-Speed modems”, IEEE Comm. Magazine, Oct. 1998

  • C. Nicol et al, “A Low-Power 128-Tap Digital Adaptive Equalizer for Broadband Modems”, IEEE jour. Of Solid-state Circuits, Nov. 1997

SungKyunKwan Univ.


Reference 2
Reference (2)

  • H. Lee et al, “A New Hardware-Efficient Architecture for Programmable FIR Filters”, IEEE Trans. On Circuits and Systems, Sep. 1996

  • J. Rinne et al, “Equalization of Orthogonal Frequency Division Multiplexing Signals”, Proc. Of GLOBECOM’94, pp. 415-419, Nov 27, 1994

  • “DSP Solutions for Voiceband and ADSL Modems”, Texas Instrument, June, 1998

SungKyunKwan Univ.


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