On applicable cellular positioning for UMTS

Abstract

Enabling the positioning of cellular handsets increases the safety level and at the same time opens exciting commercial opportunities for operators through providing location-based services. A major implementation obstacle, which prevents a wide deployment of cellular location techniques is the requirement of modifications of the existing network infrastructures and a need for the replacement of legacy terminals. Despite a significant amount of research on the mobile positioning problem, there are still unresolved aspects regarding applicable positioning solutions providing estimation accuracy sufficient for the majority of location-based services. Typically, the applicability of positioning technology in current networks and provided estimation accuracy yield for trade off.

The aim of the research performed in the frame of this thesis is to propose network- and mobile-based location techniques for UMTS networks that do not require any changes on the network side or in the user terminals and at the same time provide a reasonable estimation performance. This thesis provides a comprehensive overview of cellular mobile positioning with emphasis on applicable, practical approaches to the problem. The research results are mainly focused on the presentation of novel positioning techniques, performance assessment of the proposed techniques and evaluation of the impact of radio network planning on positioning accuracy.

Two applicable network-based positioning techniques (ECID+RTT and PCM) are proposed and evaluated. Consecutively, mobile-based location methods are presented that exploit signal strength measurements complemented by delay spread measurements or serving site information. Moreover, the thesis includes an extensive study on CID+RTT positioning. The performance of the proposed positioning methods is assessed through simulations and field measurements. In addition, this thesis introduces the influence of the topology planning process on the performance of the proposed positioning methods. The impact of capacity-oriented radio network planning on network-based positioning functionality and performance is evaluated in the context of numerous aspects of topology planning with emphasis on repeater deployment. The impact of the proposed network-based positioning on the network functionality and capacity is also studied.