Dynamic Resource Allocation for Relay-Based OFDMA Systems with Fairness Considerations

Capacity and coverage of a Frequency Division Multiple Access (OFDMA) network can be greatly enhanced by dynamically allocate the radio transmission resources. By including the radio resources of cooperative nodes and taking into account the fairness issue, we present a simple suboptimal solution to the problem of radio resource allocation in relaybased OFDMA cellular systems. We restrict our investigation to a single-cell system with several cooperative relay stations and mobile stations (MSs). An IEEE 802.16e-like TDD scenario is assumed and only the uplink transmission with the base station(BS) handling the resource allocation is of concern. We propose two suboptimal algorithms that assign power, subcarriers and cooperative relay stations to a group of MS's to meet their QoS and minimum rate requirements. Our low-complexity solutions maximize the sum rate and a fairness index while satisfies the QoS and total transmit power constraint. Numerical results show that the proposed algorithms provide robust fairness and achieve near optimal sum rate performance.