Routing Improvements using Directional Antennas in Mobile Ad hoc Networks

Abstract

In this paper, we present the design and evaluation of two techniques for routing improvement using directional antennas in mobile ad-hoc networks. First, we use directional antennas to bridge network partitions by adaptively transmitting selected packets over a longer distance, using the capabilities of the directional antenna, yet still transmitting most packets shorter distance in order to reduce power consumption and interference. Through simulations, we demonstrate the effectiveness of our design by modifying the Dynamic Source Routing (DSR) protocol, an on-demand ad hoc network routing protocol. Our simulations show that the modified protocol is able to effectively bridge network partitions, and that the protocol is otherwise equivalent to the original protocol when no partitions are present. Second, we propose a method to use directional antennas to repair routes in use when an intermediate node moves out of wireless transmission range along the route. By using the capability of a directional antenna to selectively transmit packets over a longer distance, we bridge the break in the route caused by the intermediate node's movement, thus reducing packet delivery latency and avoiding dropped packets and additional routing overhead. We present the results of simulations giving a preliminary performance evaluation of this technique demonstrating its effectiveness.