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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.

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 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.

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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