Space link simulator for development of a new standard CCSDS file delivery protocol

Terrestrial network based file transfer protocol is known to be unacceptable for the space network environment. The Consultative Committee for Space Data Systems (CCSDS) is about to propose a new file transfer protocol for use in both space and ground based networks, named CCSDS File Delivery Protocol (CFDP). CFDP is based on packet oriented protocols as its underlaying network layer. The supported packet protocols include CCSDS packet standard protocol and TCP/IP. Space communication links display specific characteristics different from those of terrestrial ones: larger link delay, higher bit error rates, bursts of errors, packet deordering, etc. For use in CFDP implementation a packet protocol based space link simulator is designed and implemented. This space link simulator, named LinkSim, can simulate not only distance driven link delay, but also link quality and link diversity. This paper presents the organization of the space link simulator and the algorithms used to emulate each link characteristic feature. An example configuration is also discussed.