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US005596604A
[ii] Patent Number: 5,596,604
[45] Date of Patent: Jan. 21, 1997
OTHER PUBLICATIONS
Bingham, "Multicarrier Modulation for Data Transmission: An Idea Whose Time Has Come", IEEE Communications Magazine, pp. 5-(May 1990).
Chow et al., "A Discrete Multitone Transceiver System for
HDSL Applications", IEEE Journal on Selected Area in
Communications, vol. 9, No. 6, pp. 895-908 (Aug. 1991).
Chow et al., "Performance Evaluation of a Multichannel
Transceiver System for ADSL and VHDSL Services", IEEE
Journal on Selected Areas in Communications, vol. 9, No. 6,
pp. 909-919 (Aug. 1991).
Heming et al., "ADSL: The On-Ramp to the Information
Highway", Telephony, pp. 20, 24-26 (Jul. 1993).
Clark et al., "Interleaver Structures for Coded Systems",
Error-Correction Coding for Digital Communications, Sec-
tion 8.3, pp. 347-349.
Primary Examiner—Stephen Chin
Assistant Examiner—T. Ghebretinsae
Attorney, Agent, or Firm—Hickman Beyer & Weaver, LLP
[57] ABSTRACT
A transmission system using multicarrier modulation applies FECC (forward error correcting code) coding and codeword interleaving differently to input signals from a plurality of different data channels to produce encoded data signals having different reliabilities and different coding delays. Bits of encoded data signals having relatively less delay are allocated to carriers that are subject to relatively more attenuation and/or channel noise, and hence that are allocated fewer bits for transmission in each symbol period, to reduce the effects of impulse noise. The data channels can comprise video, data, and control channels transmitted on an ADSL (asymmetric digital subscriber line) two-wire telephone line.
22 Claims, 3 Drawing Sheets
