CROSS-LAYER RELAY SELECTION FOR COOPERATIVE RELAY SYSTEM IN IEEE 802.16j NETWORK

The IEEE 802.16j amendment has been developed to improve the performance of the IEEE 802.16e standard in terms of its network capacity and coverage area via employment of relay stations. An optional feature of cooperative relay has been initiated to fully utilize multihop network environment. This work focuses on the selection of cooperative relay path/paths through cross-layer approach to forward data from source to destination. The selection scheme jointly considers the signal-to-noise ratio (SNR) from physical (PHY) layer and buffer status from medium access control (MAC) layer. The SNR of the communication link between the basestation and the mobile station has to be compared to a certain threshold before making decision on the optimal cooperative relaying mode. Numerical and simulation results show that cooperative relaying improves the throughput and delay of the IEEE 802.16j system. In addition, the average transmission time of cooperative relay system decreases when the parameter from the MAC layer is considered in the relay selection scheme.