Design and Evaluation of Multi - Channel Multi - Hop Wireless Networks

Wireless networks have been widely deployed in the past few years. With rapidly increasing number of users, it is important to maximize utilization of given resources to achieve high performance. Among many approaches, the aim of this dissertation is in utilizing available frequency spectrum, which may be divided into multiple non-overlapping channels. Particularly, we focus on the case where wireless nodes are equipped with a single network interface, which can operate on any one channel at a given time. Wireless network standards such as IEEE 802.11 provide multiple non-interfering frequency channels, where multiple communications can take place simultaneously. However, current protocols cannot exploit this availability to achieve high performance. The main challenge in utilizing multiple channels is the fact that a node equipped with a single network interface can only operate on a single channel, although it is capable of switching its operating channel. When two nodes want to communicate, they must be operating on the same channel. Thus, to support multiple channels, protocols need to properly assign and coordinate channels among nodes. Without careful design, multi-channel protocols may not be able to achieve higher performance than single-channel protocols. In this disseration, we first identify issues in designing a multi-channel multi-hop network, with the focus on layer-2 and layer-3 protocols. Based on the observations, we develop medium access control (MAC) and routing protocols that can utilize multiple channels with a single interface. Finally, we evaluate the multi-channel protocols through simulation and a prototype implementation.