Backup radio site identification in air traffic control systems

The identification of backup radio sites, to increase the availability of the future air/ground (A/G) air traffic control (ATC) systems, is investigated, When there is an A/G communications failure, due to a radio site or an ATC controller access failure, another site (or sites) provides the service. The backup site should be capable of providing full coverage of the desired airspace known as the service volume. Meeting the full coverage conditions by one site or a group of sites is analyzed. It is concluded that identification of one site providing full coverage can be determined easily. The identification of a group of sites, each with partial coverage and providing full coverage is analyzed in detail. An algorithm involving both analytical and numerical approaches is described. It determines if two radio sites with given geographical coordinates, and each with partial coverage of a given cylindrical service volume, can provide full coverage. This algorithm can be implemented as a computer program to process a database of radio sites     

Capacities of mobile air/ground radio communication systemsemploying cylindrical cells

Cylindrical cells represent actual service volumes used in terminal areas (airports) for air traffic control (ATC) communications between pilots and ground controllers. The channel capacities of simplex and duplex frequency division multiplexing (FDM) mobile air/ground (A/G) radio communication systems employing cylindrical cells are compared assuming a network of identical cylindrical cells and a dedicated radio channel per group of aircraft and its ground controller. The two systems are compared considering both cochannel and adjacent channel interferences for analog and digital modulation. Then, capacities of duplex FDM and code division multiplexing (CDM) are compared under the same assumptions for digital modulation. The capacity of FDM depends mainly on the frequency reuse distance while the capacity of CDM is limited by the self users interference. This work shows that the capacity ratio of duplex and simplex FDM systems depends on the cell dimensions. It also shows that considering ATC requirements, FDM provides a higher capacity than CDM for all the cell dimension ranges considered