Design, implementation, and characterization of a cooperative communications system

Patrick Murphy, Ashutosh Sabharwal

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Cooperative communications is a class of techniques that seek to improve reliability and throughput in wireless systems by pooling the resources of distributed nodes. Although cooperation can occur at different network layers and time scales, physical-layer cooperation at symbol time scales offers the largest benefit in combating losses due to fading. However, symbol-level cooperation poses significant implementation challenges, particularly in synchronizing the behavior and carrier frequency of distributed nodes. We present the implementation and characterization of a complete real-time cooperative physical-layer transceiver built on the Rice University Wireless Open-Access Research Platform (WARP). In our implementation, autonomous nodes employ physical-layer cooperation without a central synchronization source and can select between non-cooperative and cooperative communications per packet. Cooperative transmissions use a distributed Alamouti space-time block code (STBC) and employ either amplify-and-forward (AF) or decode-and-forward (DF) relaying. We also present experimental results of our transceiver's real-time performance under various topologies and propagation conditions. Our results clearly demonstrate significant performance gains (more than 40× improvement in packet error rate in some topologies) provided by physical-layer cooperation, even when subject to the constraints of a real-time implementation. Finally, we present methodologies for isolating and understanding the sources of performance bottlenecks in our design. As with all our work on WARP, our transceiver design and experimental framework are available through the open-source WARP repository for use by other wireless researchers.

Original languageEnglish (US)
Article number5783355
Pages (from-to)2534-2544
Number of pages11
JournalIEEE Transactions on Vehicular Technology
Issue number6
StatePublished - Jul 2011


  • Cooperative communications
  • decode-and-forward relaying
  • distributed space-time block coding
  • orthogonal frquency-division multiplexing
  • performance analysis
  • physical layer
  • synchronization

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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