Performance Evaluation of a Launcher Network based on Commercial-Off-The-Shelf Ethernet Technology

The objective of the paper is to propose and evaluate the performance of a low cost Ethernet network architecture applied in small launchers, in order to interconnect the terminals (on-board computer, telemetry apparatus, Inertial Reference System,...) performing the Guide, Navigation and Control (GNC) operations and producing/receiving telemetry traffic. The aerospace industry is interested in low-cost Ethernet technologies for their use as telecommunications networks within spacecraft (launchers and satellites). Current networks (e.g. 1553B bus) are characterized by low performance in terms of supported bit rates and very high maintenance costs. Some evolutions of the Ethernet standard (ARINC 664, TTEther-net, Time Sensitive Networking) have been proposing for some years now to meet the real time requirements of aerospace applications. Finally, the most ready solution is TTEthernet, standardized by the Society of Automotive Engineers as AS6802 standard, it is able to support determinism on single messages flows. Its disadvantage is the high cost, consequence of the use of a proprietary technology. The main contributions of the paper are the following: i) the definition of a low cost Ethernet architecture, referred to as Flexible Time Triggered Ethernet (FTTE), able to support services characterized by deterministic delay requirements; ii) the modelling of the message scheduling as a heap of pieces problem whose solution is pursued by using the max-plus algebra; this approach will allow us to define a low computational complexity heuristic; iii) the evaluation of the proposed solution in a real network scenario characterized by the messages of VEGA, a small launcher defined by European Space Agency and Italian Space Agency. We will compare the results of the heuristic algorithm to those obtained in case the operation mode of the network is based on TTEthernet technology. Though, our solution is less expensive for the use of traditional Commercial-Off-The-Shelf Ethernet switches, its performance approaches the one of TTEthernet when cut through switching technology is used, especially for low traffic and small network scenario.