On building a cooperative communication system: Testbed implementation and first results

Ashutosh Sabharwal, Patrick Murphy, Behnaam Aazhang

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


We present the results from over-the-air experiments of a complete implementation of an amplify and forward cooperative communications link. Our custom OFDM-based physical layer uses a distributed version of the Alamouti block code, where the relay sends one of the branches of Alamouti-encoded symbols. First we show analytically and experimentally that amplify and forward protocols are unaffected by carrier frequency offsets at the relay. This result allows us to use a conventional Alamouti receiver without change for the distributed relay system, thereby allowing cooperative systems to reuse components of current (noncooperative) systems. Our full system implementation shows gains of up to 5.5dB in peak power constrained networks. Thus, we can conclusively state that even the simplest form of relaying can lead to significant gains in practical implementations.

Original languageEnglish (US)
Article number972739
JournalEurasip Journal on Wireless Communications and Networking
StatePublished - 2009

ASJC Scopus subject areas

  • Signal Processing
  • Computer Science Applications
  • Computer Networks and Communications


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