Achievable Rates for Conferencing Multiway Channels

A generalization of the additive Gaussian two-way channel to M users is considered. Such channels contain implicit feedback in the sense that the channel output signals observed by the different encoders are correlated. While the benefits of feedback are shown to be negligible at high SNR, for moderate SNR, feedback can play a significant role in boosting the sum-rate performance. To highlight this potential gain, the special case of the M-user multiway channel with a common output is considered. By taking insights from Kramer's Fourier MEC, a feedback strategy is introduced and shown to strictly dominate the performance of a pre-log optimal non-feedback strategy. Furthermore, an upper bound is derived to show this feedback strategy achieves the sum-rate capacity beyond a certain SNR threshold. Under per-symbol power constraints, this upper bound can be tightened to show the feedback strategy is sum-rate optimal for all SNR values.

Published in:
2008 Ieee International Symposium On Information Theory Proceedings, Vols 1-6, 1398-1402
Presented at:
IEEE International Symposium on Information Theory, Toronto, CANADA, Jul 06-11, 2008
Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa

 Record created 2011-10-17, last modified 2018-03-17

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