Development of CCSDS Proximity-1 protocol for ISRO's extraterrestrial missions

Proximity-1 protocol has been the key in successful communication link establishment for a number of extraterrestrial missions. In recent years ISRO has flown missions to the moon and Mars. Given the reliability of Proximity-1 protocol over short distances, it was decided to develop the protocol for ISRO's future space missions where a short haul communication link is required for communication between Rovers, Landers and Orbiters. In this paper we discuss the implementation of Proximity-1 protocol with reference to the requirement of Indian spacecrafts. The paper discusses the modifications and customization made during implementation of the protocol under the purview of protocol standard. Requirements and feasibility of new features such as proximity safe mode and data interface unit are discussed with possible scenarios which may employ them. The safe mode allows usage of all proximity features, but with a greater protocol control and reduced complexity. Data interface unit allows proximity to function as independent module and communicate with higher layers via high speed interfaces. The paper details the response to directives and generation of notifications at various sublayers of the protocol. The protocol is developed and tested on an FPGA platform. Test setup and testing strategies used to evaluate the performance of the protocol at baseband level are also discussed.