Circularly multi-directional antenna arrays with spatial reuse based MAC for aerial sensor networks

In this paper, we introduce a novel multiple access scheme for aerial sensor networks employing adaptive antenna arrays with spatial reuse. Spatial reuse has been adopted to enable simultaneous data transmission among unmanned aerial vehicles in a context of spatial diversity. This work introduces two types of UAV: a single main actor UAV and multiple actor UAVs. Since these UAVs cooperatively perform a mission, packet collisions and signal interference can degrade a real time data transmission among them. In light of this, we propose a circularly multi-directional beam forming array antenna to be used on the main actor UAV and each UAV is equipped with a directional antenna. These two kinds of antenna are deployed so that packet collisions and signal interference can be alleviated. The main UAV is positioned in the center and surrounded by actor UAVs. By using different antennas on different types of UAV and based on the UAVs positioning, the paper proposes two MAC protocols. While both proposed MAC protocols adopt a conventional IEEE 802.11 MAC, the second one introduces a certain threshold value of angle between UAVs to enable a spatial reuse. Simulation results confirm that our proposed MAC protocols offer a huge gain in system throughput compared to an IEEE 802.11 protocol.