| In the last few years, Wireless Mesh Networks (WMNs) have become increasingly popular for the broadband enterprise networking and community networking, thanks to their low-cost and flexible deployment and self-healing property. However, due to the relatively small transmission range of the mesh routers, mobile stations in WMNs may experience frequent handoffs, leading to high packet delays and loss rates, and limiting the performance of real-time applications (e.g., VoIP) over WMNs. Distinct from the traditional 802.11 WLANs, the backhaul of WMNs is fully wireless, which brings both challenges and opportunities to the mobility and association management for wireless mesh networks.;In this dissertation, we first propose a cross-layer association scheme for wireless mesh networks, which uses the end-to-end airtime cost as the association metric. The proposed association scheme considers the frame error rate for various packet sizes, the available bandwidth of the access link, and the asymmetric uplink and downlink backhaul transportation costs. Our experimental results on a Linux-based testbed show that the proposed association scheme is capable of providing the mobile stations with the highest end-to-end network performance after their association.;We then propose a backhaul-aided seamless handoff scheme (BASH), which takes advantage of the wireless backhaul feature of WMNs and allows a mobile station to probe on the backhaul channel. By utilizing the wireless backhaul, our handoff scheme reduces the Layer-2 handoff latency, and further reduces the overall handoff latency by allowing partial overlap of the Layer-2 and Layer-3 handoffs. Our handoff scheme also shortens the authentication latency by utilizing the transitivity of trust relationship. The experimental results show that BASH achieves an average Layer-2 handoff of 8.9ms, which supports real-time applications during the handoff.;Finally, we describe the 700MHz WiFi-based WMN testbed that we have deployed under both indoor and outdoor environments. Our experimental results show that the 700MHz WMN has a significantly larger transmission range and better penetration ability compared to the traditional 2.4GHz WMN, which indicates that utilizing the 700MHz frequency band will considerably enhance the performance of WMNs, including the ability to support real-time applications. |
