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US 4,924,492 AGranted
Method and apparatus for wideband transmission of digital signals between, for example, a telephone central office and customer premises
AssigneesAmerican Telephone and Telegraph Company, AT&T Information Systems Inc.
InventorsRichard D. Gitlin, Sailesh K. Rao, Jean-Jacques Werner, Nicholas Zervos
Life of this patent
Estimating the term…
Abstract
In a telephone local loop transmission arrangement, data is communicated from the customer premises to the central office utilizing a multi-dimensional, passband signal illustratively at 480 kb/s and 1.544 Mb/s.
Claims28
A data communication method comprising the steps of
- generating an outbound passband signal representing a stream of outbound data bits,
- applying said outbound passband signal to a two-wire telephone local loop,
- receiving over said telephone local loop an inbound passband signal representing a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,
- generating a replica of said echoes,
- substracting said replica from said inbound passband signal to generate an echo compensated signal, and
- recovering said inbound data bits from said echo-compensated signal,
- at least one of said inbound or outbound bit streams being at a rate of at least 160 kb/s.
4 more elements
A data communication method comprising the steps of
- generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a stream of outbound data bits,
- applying said outbound passband signal to a two-wire telephone local loop,
- receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,
- generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,
- recovering said stream of inbound channel symbols from the resulting equalized signal, and
- recovering said inbound data bits from the recovered inbound channel symbols,
- at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.
4 more elements
A data communication method comprising the steps of
- generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of a stream of outbound data bits,
- applying said outbound passband signal to a two-wire telephone local loop,
- receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a trellis coded version of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,
- generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,
- recovering said stream of inbound channel symbols by Viterbi decoding the resulting equalized signal, and
- recovering said inbound data bits from the recovered inbound channel symbols,
- at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.
4 more elements
A network termination comprising
- transmitter means operative in response to receipt of a stream of outbound data bits for generating an outbound passband signal representing said outbound data bits,
- means for applying said outbound passband signal to a two-wire telephone local loop, and
- receiver means operative in response to an inbound passband signal which represents a stream of inbound data bits and which includes echoes of said outbound passband signal for recovering said inbound data bits from said inbound passband signal, said inbound passband signal having been received over a signal path which includes said two-wire telephone local loop,
- said receiver means including echo canceller means for generating a replica of said echoes and means for subtracting said replica from said inbound passband signal prior to the recovery of said inbound data bits therefrom,
- at least one of said inbound or outbound bit streams being at a rate of at least 160 kb/s.
2 more elements
In combination,
- a two-wire telephone local loop,
- transmitter means for generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a stream of outbound data bits,
- means for applying said outbound passband signal to said two-wire telephone local loop,
- means for receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,
- means for generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,
- means for recovering said stream of inbound channel symbols from the resulting equalized signal, and
- means for recovering said inbound data bits from the recovered inbound channel symbols,
- at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.
5 more elements
A network termination comprising
- transmitter means for generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of a stream of outbound data bits,
- means for applying said outbound passband signal to a two-wire telephone local loop,
- means for receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a trellis coded version of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,
- means for generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,
- means for recovering said stream of inbound channel symbols by Viterbi decoding the resulting equalized signal, and
- means for recovering said inbound data bits from the recovered inbound channel symbols,
- at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.
4 more elements
Dependencies are inferred from the claim text.