Implementing Space Link Extension (SLE) for Very High Rate Space Links

Abstract

Space Link Extension (SLE) is a set of recommended standards for mission cross support developed by the Consultative Committee for Space Data Systems (CCSDS). The SLE recommendations define protocols for extending the space link from ground terminals to other facilities deeper within a ground network, allowing distributed access to space link telecommand and telemetry services. The SLE protocols are widely used to provide cross support between sites, programs, and agencies. Traditional SLE protocol implementations have been limited in their ability to support high data rates and large numbers of concurrent service instances. Such limited solutions were sufficient to support the needs of spacecraft health and status or older, low-rate science data. More recent missions, however, have required significantly increased data rates on both uplink and downlink paths, necessitating a new approach to SLE implementation. This paper discusses the design principles involved in implementing the SLE protocols in support of high channel and aggregate mission data rates, with particular focus on the tradeoffs necessary to provide SLE link capability at sustained single-channel rates above 1 Gigabit per second. The paper addresses significant performance bottlenecks in the conventional SLE protocol stack and proposes potential mitigation strategies for them.