Performance Comparisons of Flexible Time Triggered Ethernet and TTEthernet technologies for Space Launcher Networks

The new generation launchers require lower implementation costs inter-communication networks along with deterministic latency, and greater flexibility, to interconnect the terminals performing the Guide, Navigation and Control operations and producing/receiving telemetry traffic. Currently employed MIL-STD-1553B is no longer enough due to the demands for high bandwidth communications because it only provides a restricted bandwidth (1 Mbps) bus solution. Ethernet is an attractive high bandwidth alternative but needs additional functionality to meet avionics requirements. The well-established TTEthernet solution, which can provide determinism for individual message flows, is high cost, consequence of the use of a proprietary technology. The objective of the paper is to assess the effectiveness of a new low-cost Ethernet network design to use in launchers, through a comparison of the performance with TTEthernet. The following are the paper's main contributions: i) the definition of the Flexible Time Triggered Ethernet (FTTE), a low-cost Ethernet architecture capable of supporting services with deterministic latency needs; ii) Through the modeling of the optimization message scheduling for both solutions, a performance evaluation comparison of the proposed solution with TTEthernet is made (in a real network scenario characterized by the messages of VEGA, a small launcher defined by the European Space Agency and the Italian Space Agency). Performance approaches the one of TTEthernet when cut through switching technology is used.