Power Allocation Based on System Capacity under Cooperative Communication Systems

Different effects of power allocation between the source node and all the relay nodes on the system capacity are taken into consideration in an amplify-and-forward cooperative communication system. An optimum power allocation algorithm based on harmonic mean of relay channel strength to increase the system capacity was proposed. Furthermore, exact formulations of P_s, P_r and P_i were derived. The simulations show that the algorithm proposed increases the system capacity significantly compared with the traditional average power allocation algorithm, especially when the signal-to-noise ratio is low, the increase ratio can reach more than 90%. And the scheme proposed has a very strong practicability because of its low computational complexity.