Session-oriented Adaptive Routing for improving path stability in WLAN based mesh networks

The IEEE 802.11s standard is designed to support multi-hop mesh networking between WLAN devices. It features the HWMP (Hybrid Wireless Mesh Protocol) as its default path selection protocol which combines the proactive tree building mode and the on-demand path selection mode. The proactive mode can periodically maintain the lowest link cost route to the root node, but poses the path instability problem, where the path is unnecessarily changed when the path is updated. As a result, the performance of the network is degraded. To alleviate this problem, we propose the Session-oriented Adaptive Routing (SOAR) protocol, which recognizes each data session and prevents path switching while the data session is in progress. To achieve this, we do not switch the existing path even though the link cost may be higher than the new path, unless the potential throughput gain of the new path is considered better than the pre-determined threshold. Moreover, the new path with lower link cost is also stored and used when a new data session is initiated. We have conducted preliminary simulation studies via the ns-3 to evaluate the performance of the proposed scheme.