Downlink sub-channel allocation algorithm for OFDMA-based multi-cell networks

This paper presents a sub-channel allocation algorithm for OFDMA-based multi-cell networks where co-channel interference from nearby cells is serious in the downlink transmission. The algorithm is semi-distributed in the sense that the sub-channel allocation can be split between radio network controller (RNC) and base stations (BSs). RNC will decide the sub-channels used by each BS at the super-frame level, in order to avoid inter-cell co-channel interference. Moreover, BSs will decide the sub-channels allocated to each user to maximize entire network throughput according to the channel state information as well as the load distribution at the frame level. The sub-channel allocations at RNC and BSs are formulated as two optimization problems which are solved by RNC algorithm and BS algorithm, respectively. Simulation results show that the proposed algorithm can improve the network performance in terms of network throughput and sub-channel utilization.