A Feasibility Study on the Regional Navigation Transceiver System Using a Transceiver Position Estimation Algorithm (2006)

Global Navigation Satellite System (GNSS) represented by GPS and GLONASS is very useful and essential to almost all the field including industries, national defense and security. From these necessities many countries make efforts and investments to have their own navigation systems based on satellite such as Galileo in EU, QZSS in Japan, and Compass in China. These countries still want to have backups to their GNSS whose signal is too weak to be easily interfered. On the other hand, other countries need alternatives since developing the satellite demands immense cost. Rockwell Collins has developed an airborne pseudolite-based Battlefield Navigation System (BNS) which has wide visibility and fast maneuverability. It is, however, only a backup system, not an alternative in a strict sense, because GPS is used to estimate pseudolite’s non-fixed position. To improve this backup into an alternative, we should estimate the mobile pseudolite position without the help of GPS. Inverted GPS algorithm was suggested to be independent of the existing GNSS, but some limitations have been obstacles to its wide-use. It is hard to construct a reference pseudolite as high as all the ground stations of wide distribution can see it. Moreover, geometry and observability of the ground stations are critical factors of the system accuracy, so several mobile pseudolites outside the ground network inevitably suffer from huge position error. This paper proposes an airborne transceiver system as an alternative navigation system and triangulation using bidirectional range measurements as a method of transceiver position determination. By canceling out the clock biases via a double-differencing technique, the bidirectional range between two transceivers can be obtained. The ground stations with transceivers, which do not need a common observable pseudolite, can be extended over a huge area, so it is possible to enlarge the coverage of this system as large as a state or a small country. Additionally, mobile transceivers far from the ground network can also get their relatively accurate positions using the airborne pseudolite network, and the position accuracy is less affected by the geometry than that of inverted GPS method. The transceiver navigation system, therefore, is still working in the area where the ground-fixed transceiver stations were not established. We simulated the performance of the suggested regional navigation system using transceivers. We estimated the mobile transceivers of positions using the measurements from the other airborne and the ground-fixed transceiver networks. In this simulation, each airborne transceiver constructed navigation message based on the estimated positions, and then user solved its position receiving signals with the message. We considered a receiver noise and tropospheric error to reflect the reality, and then conducted various case studies. With only ten transceivers (five within the ground-network, the other five outside the network) at the altitude of 40km, the alternative navigation system working in 700km uI 900km region is feasible, and its performance can compete that of Galileo's Open Service. This paper will contribute to the alternative or the backup navigation system independent of the GPS with a slim budget in a short development period. The system structure and the position determination algorithm described in this paper are able to be applied to any loading vehicle including high maneuverable UAV (Unmanned Aerial Vehicle) and stationary airship. Using the simulation result, we can solve the optimal constellations for various operating heights and predict the navigation performance for verifying the system feasibility.