Adaptive resource allocation in OFDMA-based cooperative cellular network

Adaptive resource allocation is studied for OFDMA-based cooperative cellular networks. Assuming that the base station has all the channel state information (CSI), an optimization problem for adaptive subcarrier assignment, power allocation and relay selection scheme that maximizes downlink capacity of the system is formulated. Since the optimal solution is computationally complex to obtain, a suboptimal solution dividing the problem into two steps is proposed. The algorithm in the first step for allocating subcarriers and power of BS aims at exploiting multiuser diversity of OFDMA network, while greedy relay selection and iterative relay power allocation algorithms in the second step try to exploit cooperative diversity capacity as much as possible. Numerical results show that the proposed solution can achieve significant improvement on system capacity due to two diversity schemes fully utilized by the algorithms.