Fair Flow Rate Optimization by Effective Placement of Directional Antennas in Wireless Mesh Networks

Directional antennas have been used to solve interference and connectivity issues in wireless networks for some time. Many scenarios have been presented and often positive conclusions are drawn, i.e., showing the increase in capacity. However, to date the research has mainly focused on either antenna placement or transmission scheduling but not the two combined. Such consideration will become increasingly important with the advent of heterogeneous networks and other possible combinations of public access networks in the near future.} \textbf{In this paper we study the problem of maximizing the minimal flow rate from gateways to mesh routers in wireless mesh networks using a combination of directional and omni-directional antennas. We present mixed integer programming models for deploying directional antennas at appropriate nodes, and finding a corresponding transmission scheduling (with data rate adaptation) for non-preset and preset routing. By introducing directional antennas, the considered traffic objective is substantially improved, which is verified by the numerical study. Interestingly, the results also show that it is not always optimal to deploy directional antennas at all possible nodes due to the increased interference observed at non-receiving nodes within the beam width