Power allocation methods in relay-assisted network with mobile-to-mobile channels

This paper explores the relay-assisted transmission system with mobile-to-mobile links undergo cascaded Rayleigh fading. The BER (bit error rate) bounds of the system are derived through mathematic analysis assuming amplify-and-forward relaying. And the OPA (optimal power allocation) method is discussed which is based on minimizing Chernoff bound on BER performance. The paper presents two classical cases based on geometrical topology and gets optimized power distribution parameters by numerical calculations. It further emphasizes useful insights which are as bellows: when the relay is closer to destination terminal (e.g., d_R2 ¿ d₁₂/10), it should spend more than 97% power to source terminal for the first phase transmission, whereas the relay approaches to the source, an equal power method (EPA) is adopted between the source and the relay during two transmissions. Simulation results manifest that through OPA power savings can be achieved as large as 3 dB.