Jukka Lempiäinen

Optimum antenna downtilt angles for macrocellular WCDMA network

The impact of antenna downtilt on the performance of cellular WCDMA network has been studied by using a radio network planning tool. An optimum downtilt angle has been evaluated for numerous practical macrocellular site and antenna configurations for electrical and mechanical antenna downtilt concepts. The aim of this massive simulation campaign was expected to provide an answer to two questions: firstly, how to select the downtilt angle of a macrocellular base station antenna? Secondly, what is the impact of antenna downtilt on system capacity and network coverage? Optimum downtilt angles were observed to vary between– depending on the network configuration. Moreover, the corresponding downlink capacity gains varied between–. Antenna vertical beamwidth affects clearly the required optimum downtilt angle the most. On the other hand, with wider antenna vertical beamwidth, the impact of downtilt on system performance is not such imposing. In addition, antenna height together with the size of the dominance area affect the required downtilt angle. Finally, the simulation results revealed how the importance of the antenna downtilt becomes more significant in dense networks, where the capacity requirements are typically also higher.

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.

Impact of mechanical antenna downtilt on performance of WCDMA cellular network

The aim of this paper is to evaluate the impact of the base station mechanical antenna downtilt scheme on the downlink capacity of a 6-sectored WCDMA cellular network of 33/spl deg/ horizontal beamwidth antennas. The effect of the base station antenna height and vertical beamwidth together with site spacing was evaluated in a macrocellular environment and observations were made based on system level simulations utilizing a Monte Carlo approach. The results show that downlink capacity of a WCDMA cellular network obviously depends on the mechanical downtilt angle and the capacity enhancements are based on reduction of other-cell interference. Moreover, the soft and softer handover areas are changed according to mechanical downtilt angle, which clearly depends on the base station antenna height and vertical beamwidth together with site spacing.

Impact of the base station antenna beamwidth on capacity in WCDMA cellular networks

In this paper the impact of the base station antenna horizontal beamwidth on radio network capacity in WCDMA cellular networks in the downlink direction is studied. Influence of coverage overlapping and radio propagation environment together with antenna beamwidth are also studied. A radio network planning tool is used to simulate WCDMA macro cellular network performance in urban and suburban area in Tampere, Finland. By utilizing digital morphology and topography information in the simulations reliable and practical results were expected. The simulation results show that the effect of the base station antenna horizontal beamwidth on capacity is almost unremarkable in three-sectorised sites between 65/spl deg/ and 90/spl deg/ antennas. Meanwhile the capacity enhancement between 33/spl deg/ and 65/spl deg//90/spl deg/ beamwidths in six-sectorised sites is significant. Altogether, the results of this study yield for exact planning guidelines of the base station antenna configuration for different capacity needs.

HSDPA Measurements for Indoor DAS

The target of the paper is to study performance of HSDPA in indoor environment, and to provide guidelines for HSDPA coverage and capacity planning and antenna configurations selection. Field measurements with a HSDPA data card, field measurement software, and a fully functional HSDPA enabled UMTS network were performed. Indoor corridor environment was used to study the impact of different distributed antenna configurations on a HSDPA performance. In addition, pico cell configuration is compared to corresponding distributed antenna configuration, and the effect of coverage limitations on HSDPA capacity is studied. The results show, that ensuring sufficient coverage is the key factor in planning HSDPA indoor network. Signal quality can be enhanced by increasing the number of antennas in DAS, which is also visible as improved capacity. Better signal level can be achieved by pico base stations, but taking benefit of added capacity is problematic. The measurement results show that distributed antenna configuration provides better performance compared to pico cells. As a conclusion, adequate coverage planning plays an important role in planning indoor networks for HSDPA, and some additional capacity can be gained by antenna configuration optimization.

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

An Approach for Network Outage Detection from Drive-Testing Databases

A data-mining framework for analyzing a cellular network drive testing database is described in this paper. The presented method is designed to detect sleeping base stations, network outage, and change of the dominance areas in a cognitive and self-organizing manner. The essence of the method is to find similarities between periodical network measurements and previously known outage data. For this purpose, diffusion maps dimensionality reduction and nearest neighbor data classification methods are utilized. The method is cognitive because it requires training data for the outage detection. In addition, the method is autonomous because it uses minimization of drive testing (MDT) functionality to gather the training and testing data. Motivation of classifying MDT measurement reports to periodical, handover, and outage categories is to detect areas where periodical reports start to become similar to the outage samples. Moreover, these areas are associated with estimated dominance areas to detected sleeping base stations. In the studied verification case, measurement classification results in an increase of the amount of samples which can be used for detection of performance degradations, and consequently, makes the outage detection faster and more reliable.

Improving HSDPA indoor coverage and throughput by repeater and dedicated indoor system

The target of the paper is to provide guidelines for indoor planning and optimization using an outdoor-to-indoor repeater or a dedicated indoor system. The paper provides practical information for enhancing the performance of high-speed downlink packet access (HSDPA) in an indoor environment. The capabilities of an outdoor-to-indoor analog WCDMA repeater are set against a dedicated indoor system and, furthermore, compared to indoor coverage of a nearby macrocellular base station. An extensive measurement campaign with varying system configurations was arranged in different indoor environments. The results show that compared to dedicated indoor systems, similar HSDPA performance can be provided by extending macrocellular coverage inside buildings using an outdoor-to-indoor repeater. According to the measurements, the pilot coverage planning threshold of about −80 dBm ensures a 2500 kbps throughput for shared HSDPA connections. Improving the coverage above −80 dBm seems to provide only small advantage in HSDPA throughput. Of course, the pilot planning thresholds may change if different channel power allocations are used. In addition, network performance can be further improved by increasing the antenna density in the serving distributed antenna system. Finally, good performance of repeater implementation needs careful repeater gain setting and donor antenna siting.

ADVANCED ANTENNA TECHNIQUES AND HIGH ORDER SECTORIZATION WITH NOVEL NETWORK TESSELLATION FOR ENHANCING MACRO CELL CAPACITY IN DC-HSDPA NETWORK

Mobile operators commonly use macro cells with traditional wide beam antennas for wider coverage in the cell, but future capacity demands cannot be achieved by using them only. It is required to achieve maximum practical capacity from macro cells by employing higher order sectorization and by utilizing all possible antenna solutions including smart antennas. This paper presents enhanced tessellation for 6-sector sites and proposes novel layout for 12-sector sites. The main target of this paper is to compare the performance of conventional wide beam antenna, switched beam smart antenna, adaptive beam antenna and different network layouts in terms of offering better received signal quality and user throughput. Splitting macro cell into smaller micro or pico cells can improve the capacity of network, but this paper highlights the importance of higher order sectorization and advance antenna techniques to attain high Signal to Interference plus Noise Ratio (SINR), along with improved network capacity. Monte Carlo simulations at system level were done for Dual Cell High Speed Downlink Packet Access (DC-HSDPA) technology with multiple (five) users per Transmission Time Interval (TTI) at different Intersite Distance (ISD). The obtained results validate and estimate the gain of using smart antennas and higher order sectorization with proposed network layout.

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.