Satellite based voice communication for air traffic management and airline operation

Satellite based voice communication services today are typically provided by communication centers interconnecting ground based communication facilities with suitably equipped aircrafts. These communication services are either based on a radio operator relaying the radio calls or by connecting the call automatically to phone lines through a telephone gateway. Calls from ground parties to aircraft typically use telephone numbers on a private telephone network in order to reach the appropriate air-to-ground relay station, which in turn patches the call into the radio call to the aircraft, or v ia a dispatcher in a communication center. Common for these satellite based services is the fact that only a single aircraft is addressed. Further, there is no relation between boundaries controlled by Air Navigation Service Providers (ANSPs), or any other responsible agency and the coverage of a satellite beam. This is a clear disadvantage over conventional Air Traffic Management (ATM) voice communications performed via VHF radio. Situational awareness is key for the decision making process of controllers and pilots in the next generation airspace system (NEXTGEN). In VHF radio communications this awareness is automatically provided by the shared-media nature of the air waves, thus allowing commands from controllers and the corresponding read-back from pilots to be received by all listeners on a particular frequency simultaneously (propagation delay of the radio signal not considered). In addition, today's sector boundaries (horizontal and vertical) are based on traffic patterns and thus are in accordance with the major air traffic routes, where it never happens, that a single sector requires a handover between two different radio channels (i.e. different physical frequencies). We describe mechanisms that allow combining aircrafts to virtual sector groups independent of satellite beam coverage and introduce communication services by considering technical issues of satellite based communications. Aspects of NEXTGEN are addressed such as capacity, performance, and global coverage. ANSPs, FAA, Eurocontrol, and industry are working together to define IP as the next generation common network layer for voice and data communications. EUROCAE Working Group 67 (WG-67) has recently completed its recommendation documents [1], which are now ready to become ICAO recommendations. To ensure interoperability at the application layer, open standards, a center piece of the internet protocol suite, have been agreed upon by consensus. In addition we elaborate an optimization concept for satellite communication that is in the context of the WG-67 definitions. It takes into account the available data-rate, channel access methods, different end-to-end delay, and more. A translation and optimization entity between the different technologies is introduced providing the WG-67 interface definitions on the ground side and an optimized air-to-ground interface as Link Gateway (LGW). The LGW provides the key communication capabilities to both ends, the ground based voice communications network and the aircraft and handles the interface to the data-link layer (L2) capabilities provided by the data-link via the Ground Earth Station (GES). This allows designing voice communication application services independent of the underlying transport technology. For instance changing or extending the interface at the GES would not affect the Voice Communication System (VCS) or aircraft application, only changes at the LGW are necessary. Another service entity, the Sector Floor Control (SFC) performs floor control and if applicable requests appropriate resources from the GES via the LGW. Finally, we discuss the benefits of future ATM data-link concepts as well as the benefits of integration in a multi-link environment.