Yasuto Sumiya

Mitigation of log-on rush phenomenon in aeronautical satellite data communication

Recently, satellite data communication using geostationary satellites has been introduced for oceanic air traffic control (ATC). Each aircraft needs to log on to a Ground Earth Station (GES) through a satellite before it starts data transmission and log off to finish the communication at the end of a flight. Several hundred aircraft use the link through a satellite at busy times. Once the link is disconnected due to a failure of a GES or satellite, hundreds of aircraft initiate access for re-logon to a GES almost simultaneously, and the link may be congested excessively. Many aircraft in flight are not able to complete re-logon for a long time, and the safety of those aircraft is greatly endangered. This paper describes the phenomenon of excessive link congestion due to log on sequence initiations by hundreds of aircraft in the event of a GES or satellite failure, then some methods to minimize the period for re-logon, and finally the effectiveness of those methods as demonstrated through a series of simulations.

A numerical evaluation method of the revised ACAS algorithms using a smoothed spline interpolation

This paper discusses the evaluation method of Airborne Collision Avoidance System (ACAS) algorithms. The risk ratio analysis is discussed using probability theory. Natural spline functions are presented as a tool for radar data smoothing and interpolation. Finally, the risk ratios of sample situations are calculated.

Radio propagation analysis using an aircraft model for MIMO antenna system in an anechoic chamber

Recently, new aeronautical communication systems using L-band and C-band frequencies have been defined as candidates for future communication by the Aeronautical Communication Panel of the International Civil Aviation Organization. The performance of the system may be greatly improved if the Multiple-Input Multiple-Output (MIMO) antenna system is applied to the air-ground communication system. The MIMO antenna system has multiple antenna elements, which uses indirect waves, such as multipath etc., in addition to the direct wave to enhance transmission capability. It is important to analyze the effect of the surface of the aircraft on radio propagation for the introduction of MIMO antenna systems. This paper describes the radio propagation characteristics of the antenna system on aircraft, measured using a scale model and measurement equipments in an anechoic chamber. It describes the effect of the aircraft structure, such as, tail etc., on radio propagation, and the availability of the MIMO antenna system for aeronautical communication systems.1 2