Use of diversity in wireless multihop networks

Various forms of wireless multihop networks are gaining importance with the advent of affordable platforms for wireless communication. Examples include "ad hoc" networks of mobile devices, "mesh" networks of wireless routers, and networks of wireless embedded sensors. The need for these networks be multihop arises from the fact that all network nodes are not within communication range from one another. Several characteristics of wireless channels make network protocol design difficult. Examples include multiple access interference due to the shared nature of the radio medium, susceptibility to external noise and time-varying channel fading. They all lead to poor utilization of the already limited bandwidth. We respond to this protocol design challenge by exploiting various forms of diversity. In this talk, we will summarize our recent work on exploiting link diversity via a link-layer anycast mechanism, path diversity using multipath routing, channel diversity via exploitation of multiple frequency channels, and antenna diversity by using directional antennas. These designs explore interesting cross-layer interactions between the network and link layers, a topic of active interest in the wireless networking research community.