Oblivious fronthaul-constrained relay for a Gaussian channel

Adi Homri, Michael Peleg, Shlomo Shamai Shitz

Research output: Contribution to journalArticlepeer-review


We consider systems in which the transmitter conveys messages to the receiver through a capacity-limited relay station. The channel between the transmitter and the relay station is assumed to be a frequency-selective additive Gaussian noise channel. It is assumed that the transmitter can shape the spectrum and adapt the coding technique so as to optimize performance. The relay operation is oblivious (nomadic transmitters), that is, the specific codebooks used are unknown. We find the reliable information rate that can be achieved with Gaussian signaling in this setting, and to that end, employ Gaussian bottleneck results combined with Shannon's incremental frequency approach. We also prove that, unlike classical water pouring, the allocated spectrum (power and bit rate) of the optimal solution could frequently be discontinuous. These results can be applied also to a MIMO transmission scheme. We also investigate the case of an entropy-limited relay. We show that the optimal relay function is always deterministic, present lower and upper bounds on the optimal performance (in terms of mutual information), and derive an analytical approximation.

Original languageEnglish
Article number8379461
Pages (from-to)5112-5123
Number of pages12
JournalIEEE Transactions on Communications
Issue number11
StatePublished - Nov 2018


  • Gaussian information bottleneck
  • Oblivious processing
  • finite entropy
  • quantization
  • relay
  • water-pouring

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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