3-dimensional cellular systems for aeronautical mobile radio communications

A technique for designing three-dimensional cellular systems for VHF air/ground communications is proposed to solve the problem of frequency congestion of air traffic control and flight services. In VHF air/ground communication systems, a radio-line-of-sight (LOS) between the aircraft and ground station must exist. The frequency reuse distance is reduced by using the radio horizon to block cochannel interferences. In the proposed system, cells of different sizes to cover different altitude ranges are separated by different reuse distances. With nine groups of channels, the altitude range from 740 feet to 45000 feet, or from 1185 feet to 72000 feet, can be covered without interference. The proposed system utilizes the spectrum efficiently by covering a certain airspace with the minimum number of frequency channels and cell sizes