NOT LOST IN COMMUNICATION: PLANETARY SURFACE COMMUNICATION AND NAVIGATION USING WIRELESS COTS TECHNOLOGIES

摘要

This paper describes the results of an ESA led study to identify wireless technologies which could be used to provide networked communication and position location services for assets on a planetary surface. These wireless technologies are based on mature COTS standards such as WiMAX and UWB. Transport of data at rates from a few bits per second (low-power sensors) to megabits per second (real-time video) were considered at ranges from metres to tens of kilometres. A number of position determination methods were devised which operate as overlays at the media access level. These methods provide time-of-flight measurements which enable positioning with an accuracy of a few metres at the threshold of the communications system. We have performed extensive modelling of several selected systems at a number of potential landing sites on Mars. Network coverage and performance were modelled under realistic conditions using suitable Digital Terrain Models derived from Mars Express and Mars Global Surveyor datasets. The resulting coverage maps demonstrate that COTS based wireless OFDM systems will be a strong contender for providing communications and positioning services in a planetary environment. However, due to the practical constraints of mission scenarios, system deployment and safety considerations, the wireless system alone is insufficient for all positioning requirements and must be augmented by the use of next generation inertial guidance technologies.