Decimeter Positioning in an Urban Environment Through a Scalable Optical-Wireless Network

Abstract

While global positioning systems (GPSs) play a significant role in modern life, they are far from perfect. GPSs and global navigation satellite systems (GNSSs) in general are critical assets for three-dimensional positioning, navigation, and timing (PNT) worldwide. GPSs have built a remarkable track-record since their inception, meeting set performance standards and achieving impressive up-times. GPSs have become a very popular PNT sensors in a large variety of applications, including vital functions such as sustainable energy grids, telecommunication networks, and electronic banking and trading, as well as aviation, logistics and transportation, and unmanned vehicle applications. However, GPSs have several shortcomings and vulnerabilities. Typically, GPSs perform worst where they are needed most, i.e., in densely-built urban areas. In these areas, satellite signals are frequently blocked by objects that are abundantly present in these environments. This may lead to a denial of its PNT functionality. Also, signals are frequently reflected by these objects; these detoured signals are received instead of or immediately adjacent to direct line-of-sight (LoS) signals, thereby degrading its PNT performance. In addition, several authorities have expressed increasing concern about the reliance of