Optimal user association in WiMAX MMR (802.16j) metworks

IEEE 802.16j standard defines the WiMAX Mobile Multihop Relay (MMR) networks. Multihop relays are introduced to improve the network throughput and to extend the coverage area of the network. In MMR networks, the MR-BS (Multihop Relay Base Station) has to associate each User (MS) with an Access Station which can be either one of the RS or MR-BS itself. Intuitively, MR-BS can select an Access Station for MS based on Maximum SINR or Minimum Traffic or Minimum Number of Hops. However, such association schemes will lead to inefficient resource utilization. In this paper, we propose an association scheme that guarantees the required QoS and minimize the resources required to serve an MS. The proposed association scheme exploits the frame scheduling to decide on access station for an MS. By allocating minimum possible resources to a each user without violating the user service requirement, we can accommodate maximum number of users within the current frame. The frame scheduling considered for the analysis is Even-Odd scheduling which is recommended by the standard [1]. The simulation results show that the proposed algorithm will result in efficient resource utilization and have less user drop percentage compared with the other intuitive algorithms of choosing Access Station based on Maximum SINR or Minimum Number of Hops or Minimum Traffic.