Diamond channel with partially separated relays

Ravi Tandon, Sennur Ulukus

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations


We consider diamond channels with a general broadcast channel p(y, z|x), with outputs Z and Y at relays 1 and 2, respectively, and where the relays 1 and 2 have noiseless links of capacities Rz and Ry, respectively, to the decoder. For the case when Y and Z are deterministic functions of X, we establish the capacity. We next give an upper bound for the capacity of the class of diamond channels with a physically degraded broadcast channel, i.e., when X → Y → Z forms a Markov chain. We show that this upper bound is tight, if in addition to X → Y → Z, the output of relay 2, i.e., Y, is a deterministic function of X. We finally consider the diamond channel with partially separated relays, i.e., when the output of relay 2 is available at relay 1. We establish the capacity for this model in two cases, a) when the broadcast channel is physically degraded, i.e., when X → Y → Z forms a Markov chain, and b) when the broadcast channel is semi-deterministic, i.e, when Y = f(X). For both of these cases, we show that the capacity is equal to the cut-set bound. This final result shows that even partial feedback from the decoder to relays strictly increases the capacity of the diamond channel.

Original languageEnglish (US)
Title of host publication2010 IEEE International Symposium on Information Theory, ISIT 2010 - Proceedings
Number of pages5
StatePublished - 2010
Externally publishedYes
Event2010 IEEE International Symposium on Information Theory, ISIT 2010 - Austin, TX, United States
Duration: Jun 13 2010Jun 18 2010

Publication series

NameIEEE International Symposium on Information Theory - Proceedings
ISSN (Print)2157-8103


Other2010 IEEE International Symposium on Information Theory, ISIT 2010
Country/TerritoryUnited States
CityAustin, TX

ASJC Scopus subject areas

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


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