Joint Power Allocation and Beamforming for Cooperative Networks

In this paper, we investigate power allocation problem with the use of transmit beamforming in a dual hop MISO (multiple input single output) relay channel. We consider either amplify and forward (AF) or decode and forward (DF) cooperative protocols at the relay and optimize the power allocated to the relay and the source, under total transmit power constraint, to minimize the bit error rate (BER) of relaying system. Cooperative communication is viewed as a method for increasing diversity gain and reducing end to end path loss. The use of relay can create a virtual antenna array so that it allows users to exploit the advantages of multiple input multiple output (MIMO) techniques. In this work, we solve cooperative ratio, which is defined as the ratio power used for cooperative transmission over the total power. This approach is then compared to an equal power assignment method and its performance enhancement is verified by simulation results.