Joint optimization of opportunistic relaying and power allocation in cooperative OFDM networks

Cooperative OFDM transmission is an efficient solution to combat wireless channel fading and to increase system throughput in future board communication. In this paper, we consider the uplink scenario of a cellular cooperative OFDM network, in which multi-relays can forward the source´s message to base station. The uplink throughput is optimized by using decode-and-forward (DF) opportunistic relaying. We show that the problem is formulated as a mixed binary integer programming problem, which is hard to find the global optimum in terms of computational complexity. Thus we decomposed the optimization problem into two sub-problems of opportunistic relaying strategy and power allocation. First, the opportunistic relaying strategy is given by making use of the equivalent channel power gain. Second, a low-complexity power allocation algorithm is proposed. The simulation result shows that the proposed scheme can greatly improve the system throughput.