Zone Switching Diversity for Hierarchical Resource Allocation in Mobile WiMAX Networks

This article addresses downlink resource allocation in multi-cell OFDMA mobile WiMAX systems using zone switching diversity method. We propose to use fractional frequency reuse for guaranteeing the quality of service for different service flows (SFs) in the system. Our approach includes an architecture which coordinates the allocation of resources in terms of slots (the basic allocation unit in time and frequency domain in an OFDMA frame) between the radio resource controller and the radio resource agent which resides in the Base Station. The scheme for slot allocation balances between maximizing the overall throughput of the system while guaranteeing the QoS requirements for a mixture of real-time and non real-time SFs. We used simulations to compare four resource allocation schemes that represent various degrees of multi-cell coordination and taking advantage of multiuser diversity. We find a feasible hierarchical coordination combined with intra-cell multiuser diversity provides large throughput gains compared with non coordinated schemes.