Fast Layer 3 Handoffs in AODV-based IEEE 802.11 Wireless Mesh Networks

Wireless mesh networks (WMNs) are a promising networking concept to extend the range of wireless gateways by utilizing fixed relays as packet forwarders for nodes further away. WMNs use commodity IEEE 802.11 hardware running in ad-hoc mode, and routing protocols such as ad-hoc on-demand distance vector routing (AODV) to route packets between wireless gateways, fixed relays, and mobile nodes (MNs). This paper focuses on handoff-related delays specific to WMNs: delays due to rediscovery of multihop routes after a handoff. We present the pre- handoff route discovery (PRD) concept for AODV, which avoids these delays be enabling MNs to set up routes in the handoff- target network prior to handoff. Furthermore, we illustrate how PRD can be integrated with the fast handovers for mobile IPv6 (FMIPv6) approach to achieve low-latency layer 3 (L3) handoffs in AODV-based IEEE 802.11 wireless mesh networks. Our simulation results show that PRD reduces the total L3 handoff delay from multiple hundred milliseconds to less than 20 ms.