DSL Technology

1
Adaptive Suppression of Crosstalk Between DSL
Data Cables
Author Cheng King Heng Supervisor John
Homer

• DSL Technology
• Offers high-bit-rate digital information with
  the use of existing telephone infrastructure
• Most economical means of transporting
  high-bandwidth signal
• VDSL is the latest DSL technology which offers a
  much better transmission rate and bandwidth.

• METHOD LMS Adaptive Crosstalk cancellation
• An adaptive process involving the automatic
  adjustment of the tap weights of the crosstalk
  equalizer according to the computed error
  estimation.
• LMS Algorithm
• Wnew Wold µve

• Active Tap Detection
• Many of the crosstalk channel taps are zero or
  negligible
• More efficient approach because it detects the
  non-zero taps and only estimate them
• Least square based detection employed and LMS
  based equalizer employed
• Computational cost is same as standard LMS

• Simulations Results
• 8x8 crosstalk channel matrix with 10 Active taps
• SNR 1, µ 0.01

• Crosstalk within DSL cables
• Interference caused by electromagnetic radiation
  of other phone lines in close proximity
• Severe crosstalk limits the maximum data rate of
  any individual line and degrade overall
  performance of the system

• This simulation results indicates that
• they both have a similar convergence rate
• LMS with active tap detection performs better in
  terms of Steady state error