Power optimal allocation in decode-and-forward opportunistic relaying

To combat the bottleneck effect in the relay channels, this paper proposes a simple power-control algorithm for decode-and-forward cooperative networks with opportunistic relay selection. Taking advantage of the existing channel state information, which is a by-product during the process of relay selection, an optimal power allocation factor can be easily figured out. This factor is quantized into a few control bits and then fed back to the source via the existing feedback channel, i.e., the flag packet. Using the channel capacity and outage probability as metrics, the theoretical analysis and Monte-Carlo simulation corroborate that such distributed power allocation between the source and the best relay can effectively boost the system performance. Most importantly, this performance gain comes at almost no price due to just reusing the existing CSI and flag packet.