Satellite data communications have been introduced in some areas to provide the means for message exchange between air traffic controller and pilot, and for aircraft surveillance in oceanic areas. Before the completion of the standards on aeronautical satellite data communications by the International Civil Aviation Organization (ICAO), we had conducted a series of flight experiments using INMARSAT satellites to validate the draft standards. In the flight experiments, we evaluated the characteristics on transmission delay for various flight environments. In the flight experiments, only one Aircraft Earth Station (AES) was used and the effect of traffic congestion on transmission delay characteristics was not evaluated.

We reorganized the experimental equipment for the flight experiment and established a satellite data link experiment system in the laboratory. The experiment system consists of four pseudo-AES, an experimental Ground Earth Station (GES), fading simulators and experimental Air Traffic Control (ATC) equipment. This system provides the environment where the transmission delay characteristics can be evaluated for multiple AES environment in a practical satellite link condition. We also developed a computer simulation software to evaluate the transmission delay characteristics for many AES environment. This report describes the transmission delay characteristics for various traffic conditions obtained from the laboratory experiments using the satellite data link experiment system and from the computer simulations.

Satellite data communications have been introduced in some areas to provide the means for message exchange between air traffic controller and pilot, and for aircraft surveillance in oceanic areas. Before the completion of the standards on aeronautical satellite data communications by the International Civil Aviation Organization (ICAO), we had conducted a series of flight experiments using INMARSAT satellites to validate the draft standards being developed by ICAO. The result showed that the T-channel data undergo a considerable amount of transmission delay due to its transmission protocol. This report describes a periodic reporting protocol for ADS report transmission to reduce the transmission delay and performances measured in laboratory experiments. The result showed, as an example, that the transmission delay decreases by about 7 seconds using the periodic reporting protocol compared to that of the conventional T-channel protocol at a channel rate of 600 bps.