Blended secondary surveillance radar solutions to improve air traffic surveillance

The 1030/1090 MHz frequency band is allocated for air traffic surveillance, including Secondary Surveillance Radar (SSR), Traffic Collision Avoidance System (TCAS), and Automatic Dependent Surveillance-Broadcast (ADS-B) systems. Concerns have been raised that the 1030/1090 MHz frequency band will experience significant congestion to the point of inhibiting ADS-B and TCAS from meeting performance requirement minimums by 2035 in the United States. Even today, intermittent SSR transponder availability has occurred in some high-density air traffic areas. These occurrences will likely escalate as air traffic increases, resulting in the inability of air traffic control to accurately track aircraft. This paper presents three alternative methods of using variable SSR interrogation powers with respect to azimuth sectors and ADS-B aircraft tracking data to mitigate spectrum congestion. Simulation results showed that the presented methods could reduce the spectrum congestion up to 92 percent in terms of an SSR transponder occupancy time. In addition, the proposed methods lessened the required number of Mode-S interrogator identification codes about 50 percent in the simulation environment.