Bandwidth simulations of the traffic information service in contract mode (TIS-C) over VDL mode 2 with the ACTS simulator

The concept of traffic information services in contract mode (TIS-C) is new, in that it proposes client-server protocols between the air and the ground similar to those known from the World-Wide Web by extending these with contractual behaviour for mobile safety applications. The advantages of TIS-C in comparison to traffic information services in broadcast mode (TIS-B), especially when combined with a mandate for automatic dependent surveillance-broadcast (ADS-B) based on cheap and available MODE-S technology have been discussed in previous work. In addition it has been argued that TIS-C even when operated over the available digital link mode 2 (VDL 2) can fulfill basic requirements of applications for airborne separation assurance system (ASAS), and do much more. The technical concepts and protocols of TIS-C have been elaborated and are available now. This paper presents the results of the validation of the TIS-C concept over VDL2. The validation tool that is used is the aeronautical communications technologies simulator (ACTS), which has been developed in EUROCONTROL and is one of the most performing VDL2 simulators at the moment. Different TIS-C applications for ASAS are analysed in their use of bandwidth, and several scenarios run with changing traffic loads, equipage rates, and VDL2 parameters. The technical and operational assumptions for parameters of the simulations are discussed. The work proves that the TIS-C concept over VDL 2 is possible for many applications, but also shows its limitations. The validation results emanating from the simulations are presented for the first time in this paper.