A game-theoretic approach to energy-efficient modulation in CDMA networks with delay QoS constraints

Farhad Meshkati, Andrea J. Goldsmith, H. Vincent Poor, Stuart C. Schwartz

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


A game-theoretic framework is used to study the effect of constellation size on the energy efficiency of wireless networks for M-QAM modulation. A non-cooperative game is proposed in which each user seeks to choose its transmit power (and possibly transmit symbol rate) as well as the constellation size in order to maximize its own utility while satisfying its delay quality-of-service (QoS) constraint. The utility function used here measures the number of reliable bits transmitted per joule of energy consumed, and is particularly suitable for energy-constrained networks. The best-response strategies and Nash equilibrium solution for the proposed game are derived. It is shown that in order to maximize its utility (in bits per joule), a user must choose the lowest constellation size that can accommodate the user's delay constraint. This strategy is different from one that would maximize spectral efficiency. Using this framework, the tradeoffs among energy efficiency, delay, throughput and constellation size are also studied and quantified. In addition, the effect of trellis-coded modulation on energy efficiency is discussed.

Original languageEnglish (US)
Pages (from-to)1069-1078
Number of pages10
JournalIEEE Journal on Selected Areas in Communications
Issue number6
StatePublished - Aug 2007

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


  • Cross-layer design
  • Delay
  • Energy efficiency
  • Game theory
  • M-QAM modulation
  • Nash equilibrium
  • Quality-of-service (QoS)
  • Trellis-coded modulation
  • Utility function


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