UMTS - Competing Navigation System and Supplemental Communication System to GNSS

Oliver Balbach

Abstract:	The requirement in USA of providing an accuracy of 125 m for E-911 calls has driven the positioning function of mobile phones. This requirement can hardly be fulfilled without GPS. Usually, with GSM the position is deter- mined with time difference techniques in base stations. The additional drawback is that the user has no direct access to his position (if at all). The new mobile communication standard UMTS foresees WCDMA as multiple access scheme. Therefore, similar position determination tech- niques as with satellite navigation systems can be applied and the mobile phone can locate itself. The first-glance conclusion is, that due to less disturbing environmental in- fluences (ionosphere, troposphere) but eventually higher multipath delays similar accuracies can be achieved; at least by far enough to fulfill the E-911-requirement. On the other side, nowadays existing mobile phones have yet integrated GPS modules and display the position graphically on digital maps. Thus, this technique will probably be a standard feature for mobiles when UMTS will start in a few years. The transmission of differential corrections is from the technical aspect via the GSM/UMTS network an easy task so that high accuracies can be provided with this approach. Such services are yet realized (e.g. SAPOS in Germany). GSM/UMTS as well as radio services are highly suitable for providing differential corrections for automotive ap- plications. Both will be the standard equipment of cars in the near future. Therefore, it is very astonishing why manufacturers of car navigation systems hardly apply dif- ferential techniques at the time being. The role of dGNSS seems to lose against map matching techniques. The question can be raised if it is worth it for the mobile users mass market, as e.g. tourists, automotive applications or just man-on-the-street, to integrate a second system with the possibility to apply differential corrections or if it’s sufficient to use the UMTS positioning. This paper tries to find an answer to this question and in- vestigates the achievable performance of UMTS in re- spect to navigation, i.e. accuracy and availability are es- timated. Applications are discussed and weighted against GNSS.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	519 - 527
Cite this article:	Balbach, Oliver, "UMTS - Competing Navigation System and Supplemental Communication System to GNSS," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 519-527.
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