Multipath Forwarding in WiMAX Mesh Networks with Dynamic Metrics

One of the most promising emerging wireless technologies, IEEE 802.16, supports broadband access to the Internet and Quality of Service (QoS) for multimedia applications. A WiMAX network can be deployed and operated in point-to-multipoint (PMP) mode or mesh (i.e., multihop relay) mode. In a WiMAX mesh network, there are two fundamental problems: routing and scheduling. Based on a given routing policy, a subscriber station selectively connects to a sequence of relay stations to establish a data forwarding path to a base station. Then, a scheduling policy is enforced by all relay stations and the base station along the selected path to provide the requested QoS. With the support of advanced air interface and the enhanced functional blocks (e.g., routing, self organization) proposed by the IEEE 802.16m, a WiMAX mesh network can flexibly form a partial mesh structure, in which a subscribe station can connect to multiple relay stations and a relay station can also connect to multiple neighbor relay stations to construct multiple data forwarding paths to the base station. In this paper, we present a protocol that allows a subscriber station to find multiple least-cost paths collectively providing the required services. The selection of the paths is based on statistical measurements of relay stations´ past link-quality-experience (LQE) in providing the requested QoS.