The development of next-generation Internet is driven by the demand for high-speed wireless connectivity from anywhere at anytime. As one of the two main on-going efforts for wide-area wireless Internet access, 3G infrastructure provides almost ubiquitous coverage but at low data rates. On the other hand, high data rate IEEE 802.11b devices continue to proliferate but the access infrastructure is designed to cover local areas or hot-spots. In this talk, I will present a new network architecture called UCAN, unified cellular and ad-hoc network, that combines the best of both. In UCAN networks high data rate IEEE 802.11b devices relay traffic through each other to improve the throughputs of their connections with the 3G base station. At the same time, the 3G infrastructure provides centralized coordination for the IEEE 802.11b ad-hoc networks to improve the connectivity and performance.
I will present our solutions to two specific problems in UCAN. First, to ensure the performance of the IEEE 802.11b ad-hoc network in relaying bandwidth-demanding and delay-sensitive Internet traffic, I propose our two-tier service model for channel bandwidth allocation. Fully distributed packet scheduling algorithms and localized protocols are implemented to realize the service model. I will then present our base station assisted routing to establish relay paths in the IEEE 802.11b ad-hoc networks under the dynamics of 3G downlink channel quality and node mobility. At the end of the talk I will summarize my current work and outline the future directions in wireless and sensor networking research.