A Cross-Layer Hybrid Strategy for Congestion Avoidance and Link Quality Routing in Wireless Multi-Hop Networks

The IEEE 802.11s standard was developed for wireless mesh networks. In this standard, the hybrid wireless mesh protocol (HWMP) is the default routing protocol for route selection based on the airtime metric as a measure of link quality for routing. We investigate the performance of HWMP in networks with different load levels and different link conditions. Two cross-layer optimization strategies based on the principle of joint scheduling and routing were developed and their performance compared to HWMP. One technique was a cost function technique that uses weights for the node's load and for the link quality. The second was a probabilistic based selection (PBS) method in which individual nodes in the network perform selection of neighbouring nodes with either better link quality or less load level before routing is performed. We implemented the techniques in OMNeT++ and used the INETMANET framework which has the default HWMP routing protocol implementation. Simulation results showed that for most cases, both techniques improve performance in terms of packet delivery ratio and less end-to-end latency with the PBS technique having better performance in most cases. This work aims to optimise performance by choosing better quality links for routing of data.