Improving the performance of wireless mesh networks with better medium access and routing strategies

The recent increase in the number of technologies operating in the 2.4GHz ISM band has drawn attention towards the impact they can have on each other. We highlight the ways in which coexistence can be improved by making run time adjustments to some MAC/PHY layer parameters and show their effectiveness. Furthermore, we propose a framework which exploits the pervasiveness and ubiquity of WiFi to improve coexistence among wireless technologies in the 2.4GHz ISM band. Our framework has the capability to detect the presence of wireless technologies operating anywhere in the 2.4GHz ISM band and also accounts for devices whose signatures do not exist in the database. It facilitates the WiFi AP to make decisions such as changing the channel or making MAC/PHY layer adjustments which are compliant with the configured coexistence policy thus improving the performance of the wireless devices. We have implemented our framework on real hardware and evaluated its performance in the presence of IEEE 802.15.4.;Recently, IEEE 802.11s has been ratified as an amendment to the IEEE 802.11 standard. The amendment makes provisions for a routing protocol called Hybrid Wireless Mesh Protocol (HWMP). We have studied the impact of asymmetric bi-directional links on the performance of HWMP. We show through experiments using real hardware on a testbed and the open80211s 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.