Research on the power exponent and the outage exponent in superposition coding relaying strategy

In this work, a novel two-level rate superposition coding relaying (SC-relaying) strategy is investigated. In this SC-relaying strategy, the channel state feedback of relay-to-source is introduced under a long term power constraint at source. For the SC-relaying strategy, the source power SNR exponent constraints are first obtained. And then, by using the power SNR exponent constraints, the optimizing outage exponent of the SC-relaying is proposed as well as its optimizing close-form explicit solution. From these results, it is obtained that, in the proposed SC-relaying strategy, the diversity multiplexing tradeoff (DMT) characteristics of basic signal and additional signal are not inter-independent, but have inter-constraint relationship. With asymptotical considering, the approximate DMT inter-constraint relationship of the two signals is obtained too.