The impact of access probabilities on the delay performance of Q-CSMA algorithms in wireless networks

Javad Ghaderi, R. Srikant

Research output: Contribution to journalArticlepeer-review


It has been recently shown that queue-based carrier sense multiple access (CSMA) algorithms are throughput-optimal. In these algorithms, each link of the wireless network has two parameters: a transmission probability and an access probability. The transmission probability of each link is chosen as an appropriate function of its queue length, however the access probabilities are simply regarded as some random numbers since they do not play any role in establishing the network stability. In this paper, we show that the access probabilities control the mixing time of the CSMA Markov chain and, as a result, affect the delay performance of the CSMA. In particular, we derive formulas that relate the mixing time to access probabilities and use these to develop the following guideline for choosing access probabilities: Each link i should choose its access probability equal to 1/(di+1) , where d-i is the number of links that interfere with link i. Simulation results show that this choice of access probabilities results in good delay performance.

Original languageEnglish (US)
Pages (from-to)1063-1075
Number of pages13
JournalIEEE/ACM Transactions on Networking
Issue number4
StatePublished - 2013


  • Carrier sense multiple access (CSMA)
  • Markov chain
  • scheduling
  • wireless network

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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