Efficient RTK Positioning by Integrating Virtual Reference Stations with WCDMA Network

The most advanced and proven implementation of the networked RTK is the VRS network concept. Its requirement of bi-directional communications is a critical disadvantage as this limits the robustness of the system. High costs and coverage limitations are also associated with the types of technology (i.e. UHF, GSM and GPRS) required for VRS communications. The Virtual Reference Cell (VRC) approach can be used to mitigate the disadvantages of the VRS network. This approach generates corrections for a fixed number of cells that are broadcast to the rovers. The drawback of the VRC system is a lower positioning accuracy due to the use of DGPS corrections instead of RTK. This paper proposes an RTK-VRC system whereby advantages of the VRC are maintained while achieving RTK level accuracy, mitigating high communications costs and supporting kinematic applications. The RTK- VRC system is an integration of the VRS network, to provide RTK positioning, and the WCDMA wireless network, to provide the cell structure and communications. For this system a novel communications link will be implemented using the pilot channel of the WCDMA network to minimise the communications costs. The results of a field experiment that utilises the NR&M VRS network in Australia shows that RTK positioning accuracy is achievable for VRS baselines of up to 2 km. This supports the idea of using the WCDMA cells with the RTK-VRC system.