Robust positioning systems for efficient C2 - Final report

This report provides a summary of the main activities performed in the project Robust positioning for efficient C2, from a technology perspective. The research performed within the project has focused on evaluating the potential performance of different technologies in real-world scenarios. Hence, the work has been mainly experimentallybased research, where experimental positioning systems have been developed and evaluated in as realistic settings as possible. There is a need to provide warnings when the position estimates from the GPS-receiver are larger than what is acceptable. The standard deviation of latitude and longitude delivered by the NMEA GST message can be used as an estimate of the position error. The position error is estimated quite well during good and bad conditions. However, in areas with heavy multipath propagation, such as close to buildings, reliable estimation of the position error is difficult. It is in many situations possible to detect GPS frequency interference before the receiver is affected negatively. Energy detection is a conceptually simple detector that provides good results. Carrier-to-noise (C/N0) based detectors are unsuitable for mobile urban scenarios, since they are not able to distinguish between an increased noise-plusjammer- power and a decrease in the received GPS signal power. It is possible to improve critical parameters in several military applications, e.g. the TTFF and the possibility of performing direct P(Y)-acquisition, by providing military GPS receivers with assistance data. Existing soldier positioning systems will not be able to provide room- or floor-level position accuracy. Although significantly more robust and accurate, single footmounted INS are not expected to provide room-level position accuracy during extended indoor operations. Dual foot-mounted INS cancels much of the systematic errors, as well as provides a higher robustness towards crawling and other irregular movement types. However, additional supporting sensors are required in order to keep the position error below three meters after time periods of 30 minutes. The position accuracy can be improved through cooperative localization approaches; however, it is crucial that the sub-systems uncertainty estimates are reliable when cooperative localization is applied. Furthermore, it was shown that multi-frequency RSS measurements could be useful to aid a multisensor indoor positioning system, for instance by allowing the system to perform loop-closure. Also, by integrating camerabased localization with foot-mounted INS it is possible to significantly improve the robustness and accuracy since the two systems are both likely to run into situations where the performance is insufficient and where the other system in those situations can provide high accuracies. The capability to generate 2D and 3D maps of unknown indoor environments is appealing.