Cross layer design for ad-hoc networks

Research on ad hoc networks has recently attracted a lot of interest in the communication community. However, research on the performance of ad hoc networks under Rayleigh fading channel is still in its infancy. Some works have indicated that the performance of ad hoc networks could be badly affected by Rayleigh fading channel [1]. In this paper, we identify the causes for this performance degradation and we propose a new cross-layer approach which improves the network throughput, decreases unnecessary packet transmissions, saves power and bandwidth resource, and reduces packet loss due to channel contention under IEEE 802.11 DCF. In addition, we also propose two new Markovian models: one characterising Rayleigh fading channels and the other one modelling the IEEE 802.11 DCF. Both models are then combined to study the performance of the ad hoc networks MAC layer under Rayleigh fading channel conditions. The performance of the new cross-layer approach is studied through simulations as well as through analytical models. The simulation results reveal an increase in network throughput, decrease in unnecessary packet retransmission and reduction in packet loss due to network contention. The analytical results show a close match with the simulation results.