The necessity of scheduling in compute-and-forward

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

1 Scopus citations


Compute and Forward (CF) is a promising relaying scheme which, instead of decoding single messages or forwarding/amplifying information at the relay, decodes linear combinations of the simultaneously transmitted messages. The current literature includes several coding schemes and results on the degrees of freedom in CF, yet for systems with a fixed number of transmitters and receivers. It is unclear, however, how CF behaves at the limit of a large number of transmitters. In this paper, we investigate the performance of CF in that regime. Specifically, we show that as the number of transmitters grows, CF becomes degenerated, in the sense that a relay prefers to decode only one (strongest) user instead of any other linear combination of the transmitted codewords, treating the other users as noise. Moreover, the sum-rate tends to zero as well. This makes scheduling necessary in order to maintain the superior abilities CF provides. Indeed, under scheduling, we show that non-trivial linear combinations are chosen, and the sum-rate does not decay, even without state information at the transmitters and without interference alignment.

Original languageEnglish
Title of host publication IEEE Information Theory Workshop, ITW 2017
PublisherInstitute of Electrical and Electronics Engineers
Number of pages5
ISBN (Electronic)9781509030972
StatePublished - 2 Jul 2017
Event2017 IEEE Information Theory Workshop, ITW 2017 - Kaohsiung, Taiwan, Province of China
Duration: 6 Nov 201710 Nov 2017

Publication series

NameIEEE International Symposium on Information Theory - Proceedings
ISSN (Print)2157-8095


Conference2017 IEEE Information Theory Workshop, ITW 2017
Country/TerritoryTaiwan, Province of China

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Information Systems
  • Modeling and Simulation
  • Applied Mathematics


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