Simple directional antennas: Improving performance in wireless multihop networks

Directional antennas are a promising option for use in ad-hoc networks for a variety of reasons, such as increased spatial reuse, reduced interference and enabling more efficient MAC designs. The main difficulty in using directional antennas is the complexity of coordinating and managing users' transmissions, which we collectively refer to as link scheduling. In this paper, we propose the concept of simple directional antennas (SDA), which combine several of the benefits of directional antennas while avoiding the aforementioned complexity. We investigate the use of SDA in the context of wireless multi-hop networks with contention-based MAC protocols such as ALOHA and CSMA. The metrics we consider are network connectivity, dilation, throughput, delay and energy consumption. We study their behavior extensively via analysis and simulation. In the case of slotted ALOHA, we obtain the optimum SDA parameters to maximize MAC throughput. In addition, SDA is shown to he a better strategy for reducing interference as compared to power-controlled onmi-directional antennas. Our results indicate that SDA is a good way to exploit the benefits of directionality without incurring the high computational costs of other directional antenna approaches.