Ground Based Sense and Avoid System for Air Traffic Management

Unmanned aerial vehicles (UAVs) need to "see and be seen" by manned aircraft for their safe operation. For this purpose, using available Automatic Dependent Surveillance-Broadcast (ADS-B) for all UAVs will not only saturate the 1090 MHz spectrum but will require an extra hardware. To mitigate these issues, we propose a ground based sense and avoid (GBSAA) system to enable coexistence of low altitude UAVs and ADS-B enabled flying vehicles (FVs), i.e., manned aircraft, for avoiding collisions. UAVs transmit their location information via a cellular technology to cloud, and a GBSAA base station accesses the aggregated information to send it to the ADS-B enabled FVs via ADS-B technology. We performed analytical and simulation studies to investigate the ADS-B message collision probability for different network parameters such as number of UAVs and ADS-B enabled FVs. Our study shows that for a collision probability of 0.1 with the lowest ADS-B update interval, GBSAA system can support approximately 10 times more UAVs than ADS-B only system. The proposed GBSAA approach provides a tremendous potential to integrate UAVs into airspace in a scalable manner.