Energy-aware user selection and power allocation for cooperative communication system with guaranteed quality-of-service

Energy consumption in wireless communication system is rapidly increasing due to the growth in wireless multimedia access. Combating the adverse effects of excessive energy consumption demands for energy-aware system design called green communication, which has become the major focus of many researchers recently. In this paper, we propose user selection and power allocation schemes for a multi-user multi-relay cooperative cellular system in order to minimize the cost of transmission. In the proposed schemes, the cost function is first formulated with the objective of optimizing the sum power consumption. Then it is extended to a more general multi-objective optimization scheme which jointly optimizes the sum power and throughput. The former scheme makes the system energy efficient, while the latter scheme keeps a balance between energy efficiency and throughput. In both of the schemes, quality-of-service is guaranteed in terms of end-to-end signal-to-noise ratio. Numerical results are also presented to confirm the system performance enhancement with the proposed schemes.