Information theoretic analysis of hybrid-ARQ protocols in coherent free-space optical systems

Sahar Molla Aghajanzadeh, Murat Uysal

Research output: Contribution to journalArticlepeer-review


Automatic retransmission request (ARQ) is a feedback-based data link layer technique which enhances the reliability of communication in fading channels. In this paper, we investigate the performance of hybrid-ARQ (H-ARQ) techniques in coherent free-space optical (FSO) communication systems over atmospheric turbulence-induced fading channels. Under the assumption of a Gamma-Gamma statistical fading channel model, we derive outage probability and throughput expressions for three H-ARQ protocols. We further characterize the outage performance at high values of signal-to-noise-ratio (SNR) through diversity and coding gains. Our results provide insight into the performance mechanisms of different H-ARQ protocols in coherent FSO systems and demonstrate that significant performance gains can be achieved through the deployment of H-ARQ particularly in the strong turbulence regime.

Original languageEnglish (US)
Article number6168189
Pages (from-to)1432-1442
Number of pages11
JournalIEEE Transactions on Communications
Issue number5
StatePublished - May 2012


  • Automatic retransmission request
  • Free-space optical communications
  • Outage probability
  • Throughput
  • Turbulence-induced fading

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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