Optimum spreading bandwidth for selective RAKE reception over Rayleigh fading channels

Wing C. Lau*, Mohamed Slim Alouini, Marvin K. Simon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Building on the recent developments in the performance analysis of generalized selection combining (GSC), this paper examines the optimum spreading bandwidth for a fixed-complexity GSC diversity receiver operating over independent identically distributed Rayleigh paths. For this purpose, the study considers three performance criteria: 1) average combined signal-to-noise ratio (SNR) at the GSC output; 2) average bit error probability (BEP); and 3) outage probability of the instantaneous combined SNR at the GSC output. For the average BEP criterion, results are presented for both coherent and noncoherent combining. For the average combined SNR and some instances of the average BEP optimization problem, an accurate approximate estimate of this optimum bandwidth in the form of a solution of a transendental equation is provided. In other cases, where the optimization is not easily tractable in an analytic fashion, a numeric-search procedure is used to find this optimum bandwidth for different performance criteria and system parameters of interest. Finally, simplified rule-of-thumb-type formulas are also presented as a good reference for picking the optimum spreading bandwidth given a set of system parameters and a particular performance criterion of interest.

Original languageEnglish (US)
Pages (from-to)1080-1089
Number of pages10
JournalIEEE Journal on Selected Areas in Communications
Issue number6
StatePublished - Jun 2001
Externally publishedYes


  • Diversity combining
  • Generalized selection combining
  • Hybrid SC/MRC
  • Maximal ratio combining
  • RAKE reception
  • Rayleigh fading
  • Selection combining
  • Spreading bandwidth
  • Ultrawideband radio

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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