Suboptimality of TDMA in the low-power regime

Giuseppe Caire, Daniela Tuninetti, Sergio Verdú

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


We consider multiaccess, broadcast, and interference channels with additive Gaussian noise. Although the set of rate pairs achievable by time-division multiple access (TDMA) is not equal to the capacity region, the TDMA achievable region converges to the capacity region as the power decreases. Furthermore, TDMA achieves the optimum minimum energy per bit. Despite those features, this paper shows that the growth of TDMA-achievable rates with the energy per bit is suboptimal in the low-power regime except in special cases: multiaccess channels where the users' energy per bit are identical and broadcast channels where the receivers have identical signal-to-noise ratios. For the additive Gaussian noise interference channel, we identify a small region of interference parameters outside of which TDMA is also shown to be suboptimal. The effect of fading (known to the receiver) on the suboptimality of TDMA is also explored.

Original languageEnglish (US)
Pages (from-to)608-620
Number of pages13
JournalIEEE Transactions on Information Theory
Issue number4
StatePublished - Apr 2004

All Science Journal Classification (ASJC) codes

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


  • Broadcast channels
  • Channel capacity
  • Code-division multiple access (CDMA)
  • Interference channels
  • Low-power communication
  • Multiple-access channels
  • Time-division multiple access (TDMA)
  • Wideband regime


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