Transmit power allocation for asymmetric bi-directional relay networks using channel statistics

This study proposes a transmit power allocation (TPA) scheme for bi-directional relay networks with an objective of minimising the total power consumption to meet both the service quality (i.e. the outage probability) and individual power requirements. This new scheme focuses on the amplify-and-forward protocol-based multiple-access broadcast mode with asymmetric network traffics where the bi-directional relay channel (BDRC) statistics are assumed to be available at the transmitters. A two-step method is devised to solve the optimisation problem pertaining to the total power minimisation. In the proposed method, the system outage probability is first minimised subject to both the individual and total power constraints, and then the total power consumption of the network is minimised subject to the given service quality constraint based on the preliminary solutions achieved in the first step. This two-step optimisation mechanism leads to a novel TPA algorithm for the relay and two sources of the network. Simulation results are provided to validate the proposed algorithm, showing that the proposed new power allocation scheme can significantly reduce the total power consumption, especially when the BDRC or the network traffic is asymmetric.