Spectrally efficient relay selection protocols in wireless networks

Relay networks face a fundamental challenge in terms of spectral efficiency, because relays must repeat the source information. To address this key problem, this paper presents two relay selection protocols that salvage spectral efficiency by adroitly leveraging the multiple relays. Both protocols have the feature of letting the source transmit all or most of the time. The diversity-multiplexing tradeoff (DMT) of Zheng-Tse is used to show the advantage of our protocols. The proposed protocols require minimal overhead and feedback, and have similar complexity compared to existing protocols.