Optimal power allocation schemes for amplify-and-forward relay networks with different levels of channel knowledge

This paper proposes two optimal power allocation (OPA) schemes for two-hop wireless relay networks operating in amplify-and-forward (AAF) manner. All the relay nodes in the network participate in relaying information from the source to the destination. We explore the OPA schemes among the cooperative relays to maximize the received SNR at the destination. When the instantaneous channel state information (CSI) is readily available, a closed-form solution of the OPA is derived, whereas when only the channel statistics (CS) are a priori known, the OPA scheme is developed on the basis of the statistical properties of the relaying channels. Analysis and simulations verify that the proposed schemes significantly outperform the equal power allocation (EPA) scheme.