Efficient RTK Positioning by Integrating Virtual Reference Stations with WCDMA Network

Dinesh Kumar-Mills, John Homer, Kurt Kubik, Matt Higgins

Department of Natural Resources and Mines, Locked Bag 40, Coorparoo DC, Queensland, Australia.
School of Information Technology & Electrical Engineering, University of Queensland, Australia.

DOI:                 

Abstract

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 RTKVRC 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.

Keywords

GPS, Network RTK, VRS, WCDMA, VRC

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	3GPP-R1 (2001): Technical specification group radio access network; spreading and modulation (FDD) (Release 4). 3rd Generation Partnership Project (www.3gpp.org)
[2]	3GPP-R1 (2003): Technical specification group radio access network; physical layer - general description (Release 6). 3rd Generation Partnership Project (www.3gpp.org)
[3]	Edwards S.J.; Cross P.A.; Barnes J.B.; Betaille D. (1999): A methodology for benchmarking Real Time Kinematic GPS. Survey Review, 35(273): 163-174
[4]	Fotopoulos G.; Cannon M.E. (2001): An overview of multireference station methods for cm-level positioning. GPS Solutions, 4(3): 1-10
[5]	Higgins M.B. (2001): An Australian pilot project for a real time kinematic GPS network using the virtual reference station concept. New Technology for a New Century International Conference, Seoul, South Korea, May
[6]	Hu G.R.; Khoo H.S.; Goh P.C.; Law C.L. (2003): Development and assessment of GPS virtual reference stations for RTK positioning. Journal of Geodesy, 77(5-6): 292-302
[7]	Jalloul L.M.A.; Shanbhag A. (2002): Enhancing data throughput using quasi-orthogonal functions aggregation for 3G CDMA systems. 55th Vehicular Technology Conference, May 6-9 2002, Birmingham, AL, United States, 2008-2012
[8]	Karim M.R.; Sarraf M. (2002): W-CDMA and cdma2000 for 3G Mobile Networks. McGraw-Hill, New York, 211
[9]	Landau H.; Vollath U.; Chen X. (2003a): Virtual reference stations versus broadcast solutions in network RTK -Advantages and Limitations. GNSS, Graz, Austria, Apr.
[10]	Landau H.; Vollath U.; Deking A.; Pagels C. (2003b): Virtual reference station networks - recent innovations by Trimble. Trimble, Terrasat GmbH
[11]	Lenz E. (2004): Networked transport of RTCM via internet protocol (NTRIP) application and benefit in modern surveying systems. FIG Working Week 2004, Athens, Greece, 22-27 May
[12]	Liu G.C. (2004): GPS RTK positioning via internet-based 3G CDMA2000/1X wireless technology. GPS Solutions, 7(4): 222-229
[13]	Norgaard J. (2003): Utilizing the inherent advantages of lower frequency bands for advanced communications systems. KKRRIT, Poland, 26 June
[14]	NRME. (2004): http://www.nrme.qld.gov.au/about/index.html. The State of Queensland (Department of Natural Resources, Mines and Energy)
[15]	Petrovski I et al. (2001): Practical Issues of Virtual Reference Station implementation for nationwide RTK network. GNSS International Symposium, Seville, Spain, May
[16]	Rappaport T.S. (2002): Wireless Communications Principles and Practices. Prentice Hall Communications Engineering and Emerging Technologies Series. Prentice Hall, Upper Saddle River
[17]	Retscher G. (2002): Accuracy performance of virtual reference station (VRS) networks. Journal of Global Positioning Systems, 1(1): 40-47
[18]	Valkealahti K.; Hoglund A.; Parkkinen J.; Hamalainen A. (2002): WCDMA common pilot power control for load and coverage balancing. Proceedings of 13th IEEE
[19]	International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC 20020, 15-18 Sept. 2002, Pavilhao Altantico, Lisboa, Portugal, 2002, 1412-16
[20]	Vollath U.; Deking A.; Landau H.; Pagels C. (2001): Longrange RTK positioning using virtual reference station. KIS-2001
[21]	Vollath U.; Landau H.; Chen X. (2002): Network RTK -concept and performance. Trimble (www.trimble.com) Wanninger L. (2002): Virtual Reference Stations for centimeter-level kinematic positioning. ION GPS, Portland, Oregon, Sept., 1400-1407
[22]	Wesolowski K. (2002): Mobile Communication Systems. John Wiley & Sons, West Sussex
[23]	Wübbena G.; Bagge A.; Schmitz M. (2001): Network-based techniques for RTK Applications. GPS Symposium, Tokyo, Japan, 14 Nov.
[24]	Yang K.; Kim Y-K.; Kumar P.V. (2000): Quasi-orthogonal sequences for code-division multiple-access systems. IEEE Transactions on Information Theory, 46(3): 982-993
[25]	Zhang K. and Roberts C. (2003): Network-based real-time kinematic positioning system: current development in Australia. Geoinformatics and Surveying Conference, Malaysia, 7 Apr.