ABSTRACT
Research in cooperative communications was inaugurated by the advent of the relay channel [1,2]. In this simple three-node model, a relay aids the communication a source–destination pair by overhearing the source's signal and forwarding some function of it to the destination. The Shannon capacity of the relay channel is unknown, but Reference 2 describes simple schemes that allow the relay to greatly improve throughput. Cooperative communications has been studied more recently for wireless networks in References 3 through 5. While specifics of topology, relay schemes, and so on differ between works, they share a common thread: users assist each other by forwarding each other's messages, leading to an improvement in rate and/or reliability.
