Robust and Scalable Routing in Wireless Mesh Networks Using Interference-Disjoint Backup Paths

Wireless Mesh Networks (WMNs) based on IEEE802.11s allow for ad-hoc and proactive path construction between individual Mesh Points (MPs) by utilizing the Hybrid Wireless Mesh Protocol (HWMP). In case of outages, HWMP propagates path errors through the network and reestablishes paths, resulting in a potentially large amount of broadcast traffic. Broadcast is handled at low rates and slows down the WMN additionally to the outage, which limits scalability in WMNs significantly. This paper proposes a routing mechanism that constructs and maintains main and backup paths by means of broadcast reduction, adaptive probing and efficient forwarding. Backup paths are established proactively, which limits the amount of broadcast necessary in case of an outage. Path establishment follows one of two possibilities: a link-state routing approach with global topology knowledge or in combination with a modified HWMP ad-hoc approach. For maximum robustness, we aim at backup paths that are interference disjoint to the formerly established main path, providing more robustness than state-of-the-art backup path approaches. This way, our routing will be able to withstand correlated node outages or localized jamming. Simulation results show that a global link state can be established from scratch in less than 15s for topologies up to 100 nodes, allowing path creation without any additional broadcasting. Even in case of local knowledge, path creation succeeds in less than 0.25s.