A Topology Control Approach to Using Directional Antennas in Wireless Mesh Networks

Directional antennas in wireless mesh networks can improve spatial reuse. However, using them effectively needs specialized protocol support at the MAC layer, which is always not practical. In this work, we present a topology control approach to effectively using directional antennas with legacy MAC layer protocols such as IEEE 802.11. The idea is to use multiple directional antennas on each node and orient them appropriately to create low interference topologies while maintatining network connectivity. Our approach is based on a well-known approximation algorithm to compute minimum degree spanning trees. We show via empirical studies that this approach can reduce interference significantly without increasing stretch factors to any appreciable extent. Detailed wireless network simulations also show that this approach improves end-to-end throughput of multihop flows relative to using omni-directional antennas. Three or four directional antennas per network node with only moderate beamwidths are sufficient to improve the saturation throughput of multihop flows by a factor of 3-4.