Asynchronous pseudolites and GNSS hybrid positioning

Pseudolites have the potential to extend Global Navigation Satellite System (GNSS) usage to environments where GNSS navigation is usually precluded. This also applies to asynchronous pseudolite systems, i.e. systems where the different pseudolites operate in an independent way and have the potential to enable metre level navigation. Asynchronous pseudolite systems require however dedicated strategies in order to integrate GNSS and pseudolite information. In this paper, a hybrid asynchronous pseudolite/GNSS system is developed and an extended navigation solution integrating both pseudolite and GNSS observations is obtained. Loosely-and tightly-coupled integrations are considered along with two different pseudolite positioning approaches: proximity and Receiver Signal Strength (RSS)-based location. The performance of the approaches proposed has been tested in different scenarios including static and kinematic conditions. The methods developed are effective techniques for integrating heterogeneous measurements from different sources such as asynchronous pseudolites and GNSS and suitable for different contexts.