Dynamic channel switching for downlink relay-aided OFDMA systems

A relay-aided OFDMA system model with dynamic channel switching is introduced in this paper. Specifically, this model allows each user to communicate with the base station either through direct path or relaying path. The investigated problem is formulated as maximizing system capacity with joint consideration of power distribution, subcarrier selection in direct path and subcarrier paring in relaying path. Also, the optimal criterion of selecting these two operating modes is analyzed. A low complexity algorithm is then proposed for allocating radio resources, and the performance is verified by some simulations results. It can be shown that the use of relaying does not always give better performance than only adopting direct path and an appropriate switching mechanism between direct and relaying modes can give much performance improvement.