Frequency Planning in IEEE 802.16j Networks: An Optimization Framework and Performance Analysis

The network planning aims to allow the maximum number of users and throughput in a network. This imposes a demanding performance requirement on the new relay-based architecture for mobile WiMAX, in which the capacity estimation is complex. In the network design process, where interference avoidance plays an important role, WiMAX supports reconfiguration of the subchannel usage with some frequency reuse schemes and subchannel allocation techniques already proposed in the standard and existing literature. However, these fixed strategies are not the most suitable for multihop scenarios, where some of the advantages that relay can provide are network load balancing or capacity improvement in variable conditions. The scope of this paper is first, to describe and evaluate the main two frame structures proposed in the IEEE 802.16j draft to allow multihop communications; second, to analyze the capacity improvement provided by a new optimization framework for frequency planning which considers the relay WiMAX specific characteristics that influence this process. In addition, we introduced efficient capacity calculations that will allow intensive system level simulations in a Mobile WiMAX multihop environment. Numerical results are given for various configurations allowing interesting observations about WiMAX radio efficiency. These results can be used as an order of magnitude of the real case of IEEE 802.16j network design.