A Multi-Channel MAC Protocol With Retrodirective Array Antennas in Flying Ad Hoc Networks

In this paper, we propose a multi-channel medium access control (MMAC) protocol for the exploitation of retro-directive array antennas in Flying Ad Hoc Networks (named FA-MMAC). This FA-MMAC employs multiple channels and retro-directive array antennas to adjacent unmanned aerial vehicles (UAVs) to transmit simultaneously over the same channel without causing interference. The channel utilization characteristic of FA-MMAC increases the spatial reuse of channel and thus improve the system performance. The key idea is that UAVs first exchange control packets in control window to select data channels and to align beams before exchanging data packets in the data window. In this way, the hidden-terminal and deafness problems are reduced. UAVs can reserve channels and align beams through a circular directional transmission of control frames so that the protocol can take advantage of the benefits of retro-directive array antennas of spatial reuse and increased coverage without prior knowledge of the locations. We develop both antenna model and channel model for FA-MMAC protocol. Analysis and simulation results show that our proposed FA-MMAC can offer a significant performance gain for both static and mobile scenarios than the existing MMAC and 802.11-based protocols. Our findings reported in this paper provide some insights into the performance of multi-channel Flying Ad Hoc Networks which might help network researchers to contribute in the development of next generation UAVs.