Jakub Borkowski

Practical network-based techniques for mobile positioning in UMTS

This paper presents results of research on network-based positioning for UMTS (universal mobile telecommunication system). Two new applicable network-based cellular location methods are proposed and assessed by field measurements and simulations. The obtained results indicate that estimation of the position at a sufficient accuracy for most of the location-based services does not have to involve significant changes in the terminals and in the network infrastructure. In particular, regular UMTS terminals can be used in the presented PCM (pilot correlation method), while the other proposed method - the ECID+RTT (cell identification + round trip time) requires only minor software updates in the network and user equipment. The performed field measurements of the PCM reveal that in an urban network, of users can be located with an accuracy ofm. In turn, simulations of the ECID+RTT report accuracy ofm–m for of the location estimates in an urban scenario.

Utilization of an Indoor DAS for Repeater Deployment in WCDMA

The aim of this paper is to assess the applicability of a repeater connected to a distributed antenna system for improving indoor capacity in UMTS radio network. A guarantee of sufficient coverage and capacity for in-building areas constitutes a considerable issue in topology planning, because in both links, indoor users produce high interference to the outdoor network due to significant indoor propagation losses. Presented configuration exploits effectively a repeater system that amplifies the signal from the outdoor network and delivers it for indoor locations through distributed antenna system. Implementation of the analyzed repeater system is straightforward as it does not require usage of separate carrier. Moreover, any separate scrambling codes do not have to be dedicated either. Conducted measurement campaigns reveal improvement of radio conditions due to repeater implementation that results in 35% gain of downlink capacity for indoor locations. Furthermore, in the analyzed scenario, the average value of SIR is improved by 3.41 dB that might lead to an increase of capacity in HSDPA as well. Simultaneously, the executed measurements illustrate the positive impact of the repeater configuration on the downlink capacity of the surrounding macrocellular network

Sensitivity of optimum downtilt angle for geographical traffic load distribution in WCDMA

The target of this paper is to evaluate the impact of geographical traffic load distribution the optimum downtilt angle of macrocellular WCDMA network. Moreover, the aim is to solve the feasibility of the usage of fast rate RET and to evaluate its possible capacity gain with respect to distribution of traffic load. The simulation results have revealed how allowed range of downtilt angles varies between 6 ◦ and 14 ◦ depending on whether the traffic is concentrated closer to cell edge or closer to base station. However, with this particular network configuration, 8 ◦ downtilt angle would provide almost the maximum uplink and downlink capacities with all simulated traffic distributions (maximum 5% degradation in downlink capacity). This indicates that there is no use for fast-rate adaptation of tilt angle with respect to changes in the geographical user distribution due to its low capacity gain and possibly complex implementation algorithm. This does not totally exclude the use of RET as it facilitates network optimization regarding tilt angles. Also, fast rate RET algorithm can be used for load balancing in high loaded networks.

Cellular location techniques supporting AGPS positioning

The aim of this paper is to propose applicable cellular location techniques improving latency and enhancing service availability of AGPS in cellular networks. Attractiveness of presented assistance methods is magnified due to opportunity of deployment in a standalone mode, e.g., in regular terminals or in networks, where AGPS positioning is not supported. In this paper, both completely network- and mobile-based assistance methods will be proposed and evaluated. Presented positioning approaches include solutions for effective assistance in urban UMTS networks as well as in GSM networks deployed in a rural environment. The performance of the positioning methods has been examined by measurement campaigns conducted in an urban UMTS network and by simulations performed on a digital map describing GSM rural environment. Executed analysis has provided positive results and confirmed that proposed assistance techniques can be also deployed individually, since 90% CERP of network-based technique for UMTS sustained below 180 m is sufficient for majority of location-sensitive applications. Simultaneously, poorer accuracy at the level of 500 m for 90% of estimates reported by mobile-based solutions for GSM can still improve AGPS performance or substitute satellite-based positioning for location-sensitive services, which do not require high accuracy.

Optimization Aspects for Cellular Service Performance and Mobile Positioning in WCDMA Radio Networks

The aim of this paper is to evaluate the impact of selected topology planning aspects on performance of WCDMA cellular network and mobile positioning techniques. The assessment is based on field measurements and simulations. Capacity improvement is illustrated for the network topology when antenna down tilt, sectoring, and repeaters are considered. In turn, two network-based location methods (CID+RTT and PCM) are selected for evaluation of the accuracy in a radio environment optimized for the maximum capacity. Presented results yield for a compromise if both, radio capacity and the CID+RTT, are aimed to be maximized through antenna down tilting and sectoring. On the other hand, topology optimization through repeater deployment improves the positioning accuracy as well. Considered topology optimization methods affect the PCM accuracy when the underlying database is intended to operate in a non-optimized topology, however the mean value of the accuracy is still on an appropriate level.