Architecture and Performance Evaluation of the Space Communication Protocol Proximity-1

Abstract

The amount of data generated during missions to other planets is ever-increasing. To accommodate the requirements on communication equipment, relay communication such as lander-satellite-earth links are used. For short-range communication between a lander and a satellite, protocols such as Proximity-1 are used. This report describes the implementation, testing and evaluation of the Data link layer of the Proximity-1 space communication protocol. The implementation, called Proximity-1 module, can establish a communication session with a remote Proximity-1 transceiver, transfer data, and reconfigure the radio link if needed. The Proximity-1 module is entirely implemented in hardware in order to off-load work from the On-Board Computer (OBC) of the system in which the module is used. The Proximity-1 module is designed to be as exible as possible in order to ease the task of incorporating it into a host system. The internal design of the Proximity-1 module is divided into blocks which correspond to the sublayers defined in the Proximity-1 standard. Each block is connected using streaming handshake interface. The well-defined block functionality and handshaking interfaces means that blocks implementing additional functionality can easily be added into the design for future expansions. In order to ensure an efficient design, the module is designed to provide an evenly distributed workload throughout the implementation. In addition, a performance enhancing acknowledgment strategy which is not part of the Proximity-1 standard is proposed and implemented. The configuration can be used to reduce the number of acknowledgment messages sent in a communication session and hence increase the effective data throughput.