Optimum power compensation for error propagation in relay-assisted wireless networks

It is known that relay assisted wireless transmission in a triplet, which consists of a source node, intermediate relay node and a destination node results in less power consumption than direct transmission between the source and destination pair. However, extra power compensation is needed for error propagation in the relay-assisted scenario to provision the same end-to-end bit error rate (BER) constraint as the direct transmission. This key point is neglected in the literature. In this paper, we first quantify the impact of power compensation on power savings due to relaying for M-ary QAM modulation schemes, and compare power savings performances of simple relaying and regenerative repeating at the intermediate node. Second, we present upper and lower bounds for the power savings under consideration of lognormal shadowing.