Towards the performance analysis of IEEE 802.11 in multi-hop ad-hoc networks

The performance of IEEE 802.11 in multi-hop wireless networks depends on the characteristics of the protocol itself, and on those of the upper layer routing protocol. Extensive work has been done to analyze and evaluate the performance of single hop networks under saturated traffic conditions, either through simulations or mathematical modeling. Little work has been done on the analysis of the performance of IEEE 802.11 protocol under the unsaturated traffic conditions that arise in multi-hop networks. The paper proposes analytical models and scenarios for such an analysis. ns-2 simulations with different network configurations validate the proposed models for performance metrics such as throughput, message delay, average queue length, and energy consumption. Simulation results show that the proposed models work well. Key to the modeling of the multi-hop networks is a treatment of the upper layer routing protocols that can affect the network performance through the way they forward packets and the impact of that on the traffic load. The model proposed takes into account the impact of the upper layer routing protocol by introducing a packet acceptance factor with which each relay station accepts packets from the wireless medium before forwarding the same.