Satellite augmentation of terrestial cellular mobile radio telephone systems

Cellular type mobile radio telephone systems offer the potential for higher capacity and better service than is now available. Terrestrially-based systems will be cost effective in densely populated areas, but could leave most of the land area without service. Satellites appear to offer a cost effective means to serve thinly populated areas, so a combined terrestrial and satellite system may provide an ubiquitous mobile telephone service. Reliable, good quality voice communications have been relayed through NASA's ATS satellites with mobile equipment adapted from commercially available units, demonstrating that the terrestrial and satellite cellular systems can be compatible. Vehicle position surveillance by voice bandwidth ranging from the satellites was shown to be practical and potentially accurate to about 1/10 mile. Mobile satellite communications were tested for long distance transportation, remote area search and rescue, and used for medical emergencies and disasters including the Mt. St. Helens eruption. The success of the ATS experiments has encouraged NASA to initiate studies to assess requirements, develop concepts, and plans for a multibeam demonstration satellite. International interest is evident in the 1979 WARC authorization for satellite mobile in the cellular band (806-890 MHz) and in joint Canadian/NASA discussions on the possibility of a multi-beam satellite to serve Canada and the United States.