Research On Power Allocation In Cooperative Communications

In recent years, Cooperative Communication technology has developed rapidly. Its basic idea isthat several single-antenna nodes can share each other’s antenna and cooperate with each other tosend message according to some way. Thus, a virtual multiple-antenna environment is produced toimprove the system’s channel capacity，guarantee the connectivity and broaden the coverage of thewireless networks. In communication system, power is limited resource. Effective and reasonableallocation of power among cooperative nodes can improve the system’s performance significantly.Thus, optimal allocation of the power in cooperative communication system is studied in this paper.The problem of power allocation in multi-hop Decode-and-Forward cooperative networks isdiscussed in this paper. With the limitation of the total power in the system，an Optimal PowerAllocation(OPA) algorithm is proposed to maximize the channel capacity. The result shows that theproposed OPAalgorithm improves the performance of the system significantly.To eliminate the influence of frequency selective fading, the Orthogonal Frequency DivisionMultiplexing (OFDM) technology is combined to study the problem of power allocation in OFDMmulti-hop cooperative communication system based on the above result. A kind of dual optimalpower Allocation(D-OPA) algorithm is proposed: First, power among relay nodes is optimized in asingle subcarrier, making its channel capacity maximal; Then power among subcarriers is optimized,making the channel capacity maximal of a single-hop. Thus, the system channel capacity ismaximized. Simulation results show that the proposed algorithm improves the channel capacitysignificantly compared with adaptive optimal power allocation(A-OPA), and equal powerallocation(EPA).