Optimal Power Allocation and Relay Selection in OFDM-Based Cooperative Systems

In this paper, we consider an OFDM-based cooperative diversity system where a source communicates with a destination with the help of a relay in Amplify-and-Forward relaying or Decode-and-Forward relaying. First, we propose a scheme to selecting the "best" relay to assist the transmission. And then, we present two power allocation schemes to minimize system outage probability, based on statistical channel status information (SCSI, in the form of fading distribution, and path loss information) and instantaneous channel status information (ICSI), respectively From analysis and simulation, we show that with the help of the "best" relay, full diversity order is achieved, and the power allocation schemes have better performance than fixed power allocation in terms of outage behavior.