High-Precision Time-of-Arrival Estimation for UWB Localizers in Indoor Multipath Channels

The global positioning system (GPS) has found application in many different fields, in areas where there is a good line-of-sight (LoS) to GPS satellites, this technique provides a good estimate of the location of user terminal (UT). However, in indoor and dense urban environments, localization has always been a more challenging problem for several reasons. Typically the GPS signal is not strong enough to penetrate through most materials. As soon as an object obscures the GPS satellite from the UT’s view, the signal is corrupted. This constrains the usefulness of GPS to open environments, and limits its performance in forests or in dense urban environments, as retaining a lock on the GPS signals becomes more difficult. GPS typically becomes completely useless inside buildings. However there is an increasing need for accurate localization in cluttered environments, in addition to open spaces. In commercial applications for example, the tracking of inventory in warehouses or cargo ships is an emerging need. In military applications the problem of blue force tracking, i.e., knowing where friendly forces are, is of vital importance. This is not a problem in open environments where systems can rely on GPS, but in dense urban or indoor environment, no satisfactory solution exists. Navigation in GPS-denied environment is also a pressing military need. For example untethered robots operating in enclosed environments such as urban canyons or inside buildings need accurate positioning to safely navigate. Indoor localization is of great importance for the applications that a person or a vehicle enter a building and accurately tracking its position over time is needed and the position estimate should have a precision of under one meter, i.e. on the order of some of the building feature dimensions, such as hallway width.