On the sum-capacity of degraded Gaussian multiple-access relay channels

Lalitha Sankar, Narayan B. Mandayam, H. Vincent Poor

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The sum-capacity is studied for a K-user physically degraded Gaussian multiple-access relay channel (MARC). Decode- and-forward (DF) is shown to achieve the sum-capacity and capacity region for a subclass of degraded Gaussian MARCs in which the multiple-access link from the sources to the relay is the bottleneck link. For the remaining subclass, DF is shown to achieve the K-user sum-capacity when the sources are symmetric, i.e., they transmit with the same transmit power. The optimality of DF is conjectured for the case of asymmetric sources.

Original languageEnglish (US)
Pages (from-to)5394-5411
Number of pages18
JournalIEEE Transactions on Information Theory
Issue number12
StatePublished - Dec 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences


  • Gaussian and degraded Gaussian MARC
  • Multiple-access relay channel (MARC)
  • Polymatroids
  • Sum-capacity

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