GPS-squitter channel access analysis
February 14, 1995
GPS-Squitter is a system concept that merges the capabilities of Automatic Dependent Surveillance (ADS) and the Mode S beacon radar. The result is an integrated concept for seamless surveillance and data link that permits equipped aircraft to participate in ADS and/or beacon ground environments, offering many possibilities for transition from a beacon to an ADS-based environment. A number of choices exist in the selection of the squitter channel access protocol, including the access technique (i.e., random or organized), as well as such issues as the rate of squitter transmissions and whether they are fixed or variable. This report provides an analysis of the performance of the channel access protocol selected for GPS-Squitter compared with other alternative approaches. The results of this analysis indicate that the performance of the selected protocol is superior to the defined alternatives.