Indoor and outdoor positioning system based on navigation signal simulator and pseudolites

In positioning technology, indoor positioning is known as the “last kilometer” problem because the global navigation satellite system (GNSS) cannot work indoors. A wide range of indoor positioning technologies have been developed, notably Bluetooth and Wi-Fi, and others using LED and ultra-wideband light sources. Although these technologies have had good success indoors, the indoor use of GNSS is still being pursued, and an indoor and outdoor joint location system remains a development aim. In this paper, we propose a new indoor positioning scheme that adopts pseudo-satellite (pseudolite) technology combined with a navigation signal simulator. Positioning is achieved by indoor pseudolite antennas that transmit the 'actual' satellite signals in space handled by the navigation signal simulator to an indoor user. However, the 'actual' satellite ephemeris stored in the pseudolites will bring false pseudoranges, which makes it necessary to adopt map matching technology to determine the real position. The results of our computer simulation showed that when the measurement error mainly multipath error in the room was within 1 m, the positioning results were better than 2 m in about 94% of instances. The proposed method provides a feasible solution for indoor and outdoor joint positioning. The advantages of this system include a better dilution-of-precision (DOP) than an independent pseudolite system indoors, no singular matrix, and initial point selection without limitation in the positioning equation. In addition, the introduction of a navigation signal simulator makes the system more flexible.