Variable-rate coding for slowly fading Gaussian multiple-access channels

Giuseppe Caire, Daniela Tuninetti, Sergio Verdú

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


We consider a nonergodic multiple-access Gaussian block-fading channel where a fixed number of independent and identically distributed (i.i.d.) fading coefficients affect each codeword. Variable-rate coding with input power constraint enforced on a per-codeword basis is examined. A centralized power and rate allocation policy is determined as a function of the previous and present fading coefficients. The power control policy that optimizes the expected rates is obtained through dynamic programming and the average capacity region and the average capacity region per unit energy are characterized. Moreover, we study the slope of spectral efficiency curve versus Eb/N0 (dB), and we quantify the penalty incurred by time-division multiple access (TDMA) over superposition coding in the low-power regime.

Original languageEnglish (US)
Pages (from-to)2271-2292
Number of pages22
JournalIEEE Transactions on Information Theory
Issue number10
StatePublished - Oct 2004

All Science Journal Classification (ASJC) codes

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


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