Multiplex communications – Wide area network – Packet switching
Patent
1988-12-02
1991-04-09
Ng, Jin F.
Multiplex communications
Wide area network
Packet switching
375 8, 379406, 379410, H04J 300
Patent
active
050070479
ABSTRACT:
An echo cancellation modem for full-duplex communication over a channel with a remote device in accordance with one of several possible modulation schemes suitable for different channel qualities, respectively. The modem includes an echo canceller for reducing echo components appearing in the channel signal while leaving a residual echo component in the echo reduced channel signal, a monitor for determining the quality of the channel based on an analysis of the residual echo component, and a controller for selecting an acceptable modulation scheme, based on the analysis of the monitor. The modem selects the acceptable modulation scheme prior to data communication and it also requests changes to the appropriate level of modulation during data communication when the monitor indicates that the channel quality has changed significantly. The modem requests the remote device to operate at the selected rate and begins operating at the selected rate only if the remove device concurs. In another aspect, the modem includes a fall forward flag which is used to prevent contention between the modem and the remote device which would occur if the modem repeatedly requested an increase to a higher level modulation scheme which the remote device cannot support. In another aspect, the modem includes re-initialization logic which selects the appropriate thresholds used to monitor the quality of the channel depending upon whether the modulation option is coded or uncoded.
REFERENCES:
patent: Re31253 (1983-05-01), Weinstein
patent: 3449716 (1969-06-01), Brothman et al.
patent: 3534264 (1970-10-01), Blasbalg et al.
patent: 3536840 (1970-10-01), Lee
patent: 4110558 (1978-08-01), Kageyama et al.
patent: 4524244 (1985-06-01), Faggin et al.
patent: 4562426 (1985-12-01), Forney, Jr.
patent: 4589111 (1986-05-01), Adachi
patent: 4606044 (1986-08-01), Kudo
patent: 4630126 (1986-12-01), Kaku et al.
patent: 4653044 (1987-03-01), Kudo
patent: 4736388 (1988-04-01), Eguchi
patent: 4756007 (1988-07-01), Qureshi et al.
patent: 4802189 (1989-01-01), Wedler
"Real Time Application of Trellis Coding to High-Speed Voiceband Data Transmission", H. Thapar, IEEE Journal in Selected Areas in Communications, vol. SAC-2 No. 5,9-1984, pp. 648 to 658.
"Microprocessor Implementation of High-Speed Data Modem," P Van Gerwen et al., IEEE Transactions on Communications, vol. Com-25, No. 2, 2-1977 pp. 238-258.
"Line Quality Monitoring Method", P. G. Bryant, IBM Technical Disclosure Bulletin, vol. 18, No. 8, Jan. 1976, p. 2726.
CCITT Draft Recommendation V.32.
Bargoot Carol A.
Payton John L.
Sridhar Manickam R.
Augustus Jhancy
Codex Corporation
Ng Jin F.
LandOfFree
Adaptive rate control for echo cancelling modem does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adaptive rate control for echo cancelling modem, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adaptive rate control for echo cancelling modem will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2040368