High performance static and dynamic cooperative communication protocols for the half duplex fading relay channel

Two novel communication protocols for the quasistatic coherent fading relay channel are proposed and analyzed under the diversity-multiplexing tradeoff framework. Both these protocols satisfy the half-duplex constraint and fall under the class of decode and forward (DF) protocols, wherein the relay node attempts to decode the source signal and if successful transmits the re-encoded signal. The first protocol is a static DF protocol where the relay waits for a fixed, channel independent duration before attempting to decode. It is shown that it achieves a tradeoff curve that uniformly improves upon those of the previously best known static half-duplex protocols, which are the NAF protocol and the STC3 protocol. Our second protocol is a dynamic DF protocol where the relay waits for a dynamic, channel dependent duration before attempting to decode and it is shown to achieve a tradeoff curve that uniformly improves upon the previously proposed half-duplex dynamic DF protocol.