Design, Implementation, and Characterization of a Cooperative Communications System

作者：Murphy Patrick^*; Sabharwal Ashutosh

来源：IEEE Transactions on Vehicular Technology, 2011, 60(6): 2534-2544.

DOI：10.1109/TVT.2011.2158461

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

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 noncooperative 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 40x 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.

• 出版日期2011-7