Reliable Transmission of Aircraft Data over Satellite
After almost two years to recover the flight data recorder of Air France Flight 447 and, by January 2015, still no sign of Malaysian Airlines Flight 370, the public and media ask the question: ?How is it possible to have almost worldwide Internet access in the cabin but not being able to track the position of an aircraft?? One answer to the question is that the passenger pays for Internet access in the cabin while the airline would have to pay for transmission of sensor data, such as the aircraft position. Furthermore Internet access in the cabin is offered on a best effort basis without any guarantees with regard to delay, throughput and loss rate. In this paper we present a simple system capable of transmitting critical data to the ground and evaluate the statistical distribution of the end-to-end delay a transmitted data packet encounters. Signal Flow Graphs are used to systematically model the transmission system with regard to delays encountered by a packet, including those caused by retransmissions of lost data. Results for the Inmarsat-4 Broadband Global Area Network (BGAN) service are derived, but the method is applicable to many other transmission systems.
000: Allgemeines, Wissenschaft