Pedestrian navigation with high sensitivity GPS receivers and MEMS

Abstract

Following a brief introduction to pedestrian navigation and dead-reckoning methods, the characteristics of the current global navigation satellite system (GNSS), namely the US global positioning system (GPS), and its suitability for pedestrian navigation are reviewed. Error sources affecting system performance under both line-of-sight and attenuated signal conditions are described. Attenuated signals can now be acquired and tracked under certain indoor environments, but accuracy and other performance measures are degraded. Pedestrian navigation examples under the forestry canopy and indoor are used to show not only performance but also performance variability as a function of the environment. The use of micro-electro-mechanical systems (MEMS) to aid GPS is introduced. Their advantages and limitations are described through the use of an urban canyon test in a city core, a very harsh RF environment due to signal multipath. It is found that although MEMS aiding substantially improve performance, test conditions have a major impact on actual performance. As a consequence, enough test results are not available at this time to fully characterize performance as a function of the environment due to the high variability of the latter. Accuracy, for instance, varied between 15 and 150 m in the few tests deported herein. Finally, a few predictions are made regarding potential future improvements.