Optimal resource allocation in multihop relay-enhanced WiMAX networks

Multihop relaying in WiMAX networks is considered an increasingly attractive technology for providing throughput enhancement, coverage extension, or both. In this paper, we consider deploying non-transparent relay stations (RSs) that transmit on the same carrier frequency as the base station (BS) for the purpose of coverage extension. Since it is possible that the RSs and BS are transmitting/receiving simultaneously to/from the subscriber stations (SSs) during the access zone period, it is challenging to schedule resources optimally for serving SSs in a fair manner. We propose an optimal scheduling scheme that preserves fairness among active SSs, and compare its performance with two different resource allocation schemes, namely, the overlapped and orthogonal in terms of cell throughput and outage performance. Our numerical results show that proposed scheme can achieve more throughput than the orthogonal scheme, while maintaining the fairness and lower outage performance of the orthogonal one.