Energy-Efficient Resource Allocation in OFDM Relay Networks under Proportional Rate Constraints

This paper investigates the energy efficient resource allocation for OFDM relay networks, where K users receive information via L helping relays. For such a system, an optimization problem is formulated to maximize the system energy efficiency (EE) by jointly optimizing the relay selection, subcarriers assignment and power allocation under the proportional rate constraints and available power constraint. Since this problem is non-convex with integer variables, which is nontrivial to be solved by using known methods, we design an efficient low- complexity algorithm to solve it. Simulation results show that by using our proposed resource allocation scheme, the approximate optimal results can be achieved. It is also shown that the circuit power (including a rate-dependent part and a constant part) in the consumed power has a great impact on limiting the EE resource allocation to obtain a high spectral efficiency. Besides, the effects of the relay selection, subcarrier assignment and power allocation on the system performance are also discussed via simulations.