Scan and wait combining (SWC): A switch and examine strategy with a performance-delay tradeoff

Hong Chuan Yang*, Marvin K. Simon, Mohamed Slim Alouini

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


This paper proposes and analyzes an alternative form of switch and examine combining, namely one that waits for a channel coherence time if all the available diversity paths fail to meet a predetermined minimum quality requirement. This scanning through the available diversity paths followed by waiting process is repeated indefinitely until a path with an acceptable quality is found. The performance of the resulting "scan and wait" combining (SWC) scheme is studied in terms of its average probability of error and ergodic capacity. The paper looks also into (i) the delay associated with SWC by deriving the statistics of the waiting time needed before satisfactory transmission occurs and (ii) the underlying complexity by studying the statistics of the number of diversity paths estimated per channel access. Selected numerical examples show that, for a fixed average number of channel estimates per channel access, SWC outperforms traditional diversity combining schemes at the expense of a negligible time delay.

Original languageEnglish (US)
Article number1687771
Pages (from-to)2477-2483
Number of pages7
JournalIEEE Transactions on Wireless Communications
Issue number9
StatePublished - Sep 2006
Externally publishedYes


  • Diversity techniques
  • Fading channels
  • Performance analysis
  • Switched diversity

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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