Energy Modelling and Optimization of Amplify-and-Forward Relay Transmission

摘要

Cooperative relays have been used in many wireless applications to reduce transmit power as well as adding receiver diversity. However, the energy efficiency trade-offs of relay networks have not been thoroughly investigated using a more complete system energy model. In this paper we present an energy model for a cooperative amplify-and-forward (AF) relay system that utilizes receiver diversity, and energy consumption is based on models of both analog and digital components for transmission and reception. Transmit power amplifier (PA) energy is written as a function of the following parameters: relay location, relative transmit power allocation among the transmitter and relay, spectral efficiency, transmission distance, pathloss, and target bit-error rate (BER). The energies of the remaining circuit components are added to form an AF system energy equation, which is then minimized to find the optimal relay location, transmitter and relay PA power allocations, and spectral efficiency. Results are compared to the energy of direct transmission system, and the minimum-energy system as a function of source-destination distance is investigated.