Do we really need OSTBCs for free-space optical communication with direct detection?

Majid Safari, Murat Uysal

Research output: Contribution to journalArticlepeer-review


In this letter, we investigate spatial diversity techniques for free-space optical (FSO) links with intensity modulation and direct detection (IM/DD) over log-normal atmospheric turbulence-induced fading channels. We restrict our attention to the deployment of orthogonal space-time block codes (OSTBCs) and repetition codes both of which have been recently proposed for FSO links. Our performance analysis demonstrates that, although both schemes are able to extract full diversity, repetition codes outperform OSTBCs. The performance gap increases with the increasing number of transmit apertures. Our findings clearly point out that deployment of OSTBCs is not necessary for a FSO IM/DD link.

Original languageEnglish (US)
Article number4686821
Pages (from-to)4445-4448
Number of pages4
JournalIEEE Transactions on Wireless Communications
Issue number11
StatePublished - Nov 2008


  • Atmospheric turbulence
  • Free-space optical communication
  • Space-time coding
  • Spatial diversity

ASJC Scopus subject areas

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


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