Design of a Routing Protocol that Exploits the Availability of Directional Antennas in Wireless Ad Hoc Networks

We present a new distributed routing protocol for direct-sequence spread-spectrum, mobile ad hoc packet radio networks that contain a mix of nodes with directional antennas and nodes with omnidirectional antennas. Two components of the routing protocol are jointly designed: a new congestion-based link metric that is utilized to identify multiple routes with low levels of congestion and a new forwarding protocol that can dynamically split traffic among the multiple routes based on the relative capabilities of the routes. To be able to efficiently exploit the nodes with the directional antennas, our routing approach accounts for the additional capabilities of these nodes and utilizes multiple routes to a destination if the routes exhibit low mutual coupling. We show that our joint routing and forwarding approach provides substantial improvements in network performance compared to a scheme that simply selects minimum-hop routes. Our investigations demonstrate that the most significant gains in network performance are achieved in networks in which there is a mix of nodes with different types of antennas, but gains in network performance are also achieved in networks in which all nodes employ omnidirectional antennas only