Cross-Layer Routing Design For Wireless Mesh Networks Based On Bandwidth Estimation

In recent years, Wireless Mesh Networks technology has scored big points rapidly, and it has become the key technology of next generation wireless networks. However, due to the characteristics of Wireless Mesh Networks in terms of topology, transmission link and traffic, the existing routing protocol in Wireless Mesh Networks can not fully guarantee quality of service. Therefore, how to improve radio resources utilization in the Wireless Mesh Networks, as well as provide good Quality of service(QoS) guarantee to the existing flows has become a key problem.QoS support in IEEE 802.11-based Wireless Mesh Networks relies on the networks'ability to estimate the available bandwidth on a given link.However, no mechanism or method has been standardized to accurately estimate the amount of resources remaining on a given channel.In this paper,we propose an improved available bandwidth estimation mechanism, which takes the synchronization between sender and receiver and the packet collision probability into consideration , also differentiates the channel busy state caused by transmitting or receiving from the channel sense busy state caused by carrier sensing, and thus improves the accuracy of the overlap probability of the idle channel time between sender and reciver.In order to calculate the available bandwidth under interference, the paper studies a distributed estimation scheme, which is implemented at each node for estimating the idle time on each associated channel periodically, and broadcast the numerical of idle time to other nodes within interference regularly.Based on the improved available bandwidth evaluation mechanism,the paper does research on Wireless Mesh Networks routing protocols and routing metric, and proposes a bandwidth estimation based cross-layer QoS routing protocol for Wireless Mesh Networks. According to the residual available bandwidth at each node, the algorithm predicts the feasible sending rate of a path with the consideration of inter-?ow and intra-?ow interference,as well as the admission control. Then,the paper proposes the transmission cost function of path,which is used to calculate the Path Efficiency Factor with the path feasible sending rate .The Path Efficiency Factor is used as a routing metric to select the most ef?cient one among all feasible paths, which strikes a balance between the interfering neighbor and the available bandwidth of the path. The simulation results show that the proposed mechanism can comparatively accurately estimate a link's available bandwidth. Based on the improved available bandwidth evaluation mechanism ,the proposed routing algorithm shows relatively good performance, and can enhance the network throughput, avoid the network congestion and provide better QoS guarantee.