Diversity-enabled power profile design for relay networks

Cooperative networks have caught a lot attention these days because they provide diversity which mitigates the deleterious wireless channel fading effects. So far, numerous strategies have been proposed to collect the cooperative diversity. In the link-adaptive strategy, the relay node scales the decoded symbols according to the signal-to-noise ratio (SNR) of the source-relay and the relay-destination links to exploit the cooperative diversity. In this paper, based on a general link-adaptive strategy which does not require any feedback at either source or relay, we design power profile at the relay node to enable diversity at the destination. The necessary and sufficient conditions for the design of the adaptive relay to guarantee full diversity at the destination are also provided.