Improving the Performance of Hybrid Wireless Mesh Protocol

Recently, IEEE 802.11s has been ratified as an amendment to the IEEE 802.11 standard. It adds the ability to establish a wireless mesh network. The amendment makes provisions for a routing protocol called Hybrid Wireless Mesh Protocol(HWMP). In this paper we study the impact of asymmetric bidirectional links on the performance of HWMP. We show through experiments using real hardware on a test bed and the open 80211s implementation of HWMP that such links significantly impact the performance of the protocol. We describe in detail the cause of decline in performance and attribute it to implementation issues and more importantly the inadequacy of the routing metric. Moreover, we propose solutions to the identified problems, implement those solutions by making modifications to the Linux kernel mac80211 stack and show the achieved performance gains through detailed experiments.