Telephonic communications – Subscriber line or transmission line interface – Network interface device
Patent
1988-12-29
1991-01-01
Ng, Jin F.
Telephonic communications
Subscriber line or transmission line interface
Network interface device
379410, 370 321, H04M 100
Patent
active
049824287
ABSTRACT:
In an arrangement for simultaneously exchanging digital symbols between terminals over a bidirectional transmission path, near term interference in the signal received from the transmission path is canceled by storing the sequence of successive digital symbols 1, 2, . . . , N applied to the transmission path, forming a replica of the interference from the stored digital symbols and subtracting the replica from the received signal. A signal representative of a replica of the interference occurring subsequent to the Nth digital symbol of the successive digital symbols 1, 2, . . . , N is then generated and combined with the signal having the interference corresponding to the stored symbol sequence removed to cancel the subsequent interference in the received signal. The signal representing the interference subsequent to the Nth digital symbol is generated by modifying the Nth stored symbol by an adaptive gain signal corresponding to the correlation of the subsequent interference replica signal with the signal having the interference removed, and recursively altering the modified Nth stored digital symbol with a prescribed impulse response representative of the characteristics of the bidirectional transmission path subsequent to the time periods of the sequence of successive digital symbols 1, 2, . . . , N.
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Agazzi Oscar E.
Koh Taiho
AT&T Bell Laboratories
Augustus Jhancy
Birnbaum L. H.
Ng Jin F.
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