Role of Feedback in Modulo-Sum Computation over Erasure Multiple-Access Channels

I-Hsiang Wang*, Shih-Chun Lin, Yu-Chih Huang

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

The problem of computing the modulo-sum of messages over a finite-field erasure multiple access channel (MAC) is studied, and the role of feedback for function computation is explored. Our main contribution is two-fold. First, a new outer hound on the non-feedback computation capacity is proved, which strictly improves the state of the art [1]. The new outer bound answers a previously unsettled question in the affirmative: delayed state feedback strictly increases computation capacity for the two-user erasure MAC universally. The proof leverages the subset entropy inequality by Madiman and Tetali Pl. Second, focusing on the family of linear coding schemes with hybrid-ARQ-type retransmissions, we develop the optimal computation rate with delayed state feedback. For the considered family of schemes, it is always sub-optimal to compute modulo-sum by decoding all messages first. This is in contrast to the non feedback case where sometimes the aforementioned "decode-all" strategy can reach the best known achievable rates.

Original languageEnglish
Title of host publication2017 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY (ISIT)
PublisherIEEE
Pages2293-2297
Number of pages5
StatePublished - 2017
EventIEEE International Symposium on Information Theory (ISIT) - Aachen, Germany
Duration: 25 Jun 201730 Jun 2017

Publication series

NameIEEE International Symposium on Information Theory
PublisherIEEE

Conference

ConferenceIEEE International Symposium on Information Theory (ISIT)
CountryGermany
CityAachen
Period25/06/1730/06/17

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