Tero Isotalo

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.

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

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.

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.

Techno-economical analysis and comparison of legacy and ultra-dense small cell networks

Network densification has been identified as one key enabling technology to address the 1000x mobile data challenge. This article analyzes network densification from the different deployment options perspective by looking into three mainstream technologies; Macrocells, Microcells, and Femtocells. The technologies are evaluated in a suburban neighborhood with modern residential houses. As majority of the data traffic in the network is believed to be generated by indoor users, we make a techno-economic analysis and comparison of the different deployment strategies from the indoor local area service provisioning viewpoint. Results show superior performance of low power indoor femtocell based deployment solutions in terms of coverage, capacity, energy and cost efficiency as compared to the outdoor solutions. Densifying the traditional pure Macro or Micro layers does provide improvement in the indoor coverage levels, however, due to the closer proximity of the co-channel interfering sites, the achievable capacity in the indoor environment deteriorates, which in turn also affects the energy and cost efficiency. These findings strongly motivate towards ultra dense deployments, based on indoor femtocell solutions, for addressing the local area capacity needs of the emerging future 5G networks.

Replacing terrestrial UMTS coverage by HAP in disaster scenarios

This paper discusses the use of high altitude platforms, HAPs, to provide mobile communication services to on-ground customers. The paper explains the behavior of UMTS radio network in a situation, where the service is being provided by HAP and terrestrial base stations in a disaster scenario. In the disaster scenario, a set of adjacent terrestrial cellular base stations in the middle of the network have been disabled. A HAP station has been launched to the disaster location to provide UMTS service. The possible effects between the HAP and the terrestrial UMTS network are assessed from the system point of view by analyzing the simulation results of the radio interface. The results show that the HAP is able to improve the performance in the radio network by providing UMTS coverage from the HAP station. The HAP station is able to restore the disaster area throughput to the level of 70 % from the original level. However, to achieve good network performance using HAP, careful configuration planning is required. Thus with careless HAP configuration design, the HAP service performance could totally be lost.

Fabrication of Ion-Shaped Anisotropic Nanoparticles and their Orientational Imaging by Second-Harmonic Generation Microscopy.

Ion beam shaping is a novel and powerful tool to engineer nanocomposites with effective three-dimensional (3D) architectures. In particular, this technique offers the possibility to precisely control the size, shape and 3D orientation of metallic nanoparticles at the nanometer scale while keeping the particle volume constant. Here, we use swift heavy ions of xenon for irradiation in order to successfully fabricate nanocomposites consisting of anisotropic gold nanoparticle that are oriented in 3D and embedded in silica matrix. Furthermore, we investigate individual nanorods using a nonlinear optical microscope based on second-harmonic generation (SHG). A tightly focused linearly or radially-polarized laser beam is used to excite nanorods with different orientations. We demonstrate high sensitivity of the SHG response for these polarizations to the orientation of the nanorods. The SHG measurements are in excellent agreement with the results of numerical modeling based on the boundary element method.

Indoor Planning for High Speed Downlink Packet Access in WCDMA Cellular Network

The aim of this paper is to show the special characteristics of the indoor environment related to radio propagation and furthermore to radio network planning. The aspects of the radio network planning are highlighted especially for Wideband Code Division Multiple Access (WCDMA) radio access technology that is used widely in the third generation mobile networks. Moreover, the detailed planning parameters in indoor environment are studied for High Speed Downlink Packet Access (HSDPA) in order to support high throughput data applications in Universal Mobile Telecommunications System (UMTS). The final target of the paper is to compare pico cell, distributed antenna system (DAS), and radiating cable network configurations in indoor environment to provide the optimal radio conditions for the data applications, and thus to serve highest number of mobile users. Several measurement campaigns with different antenna configurations have been conducted in order to study the effect of multi path related parameters, as delay spread of the signal. Also other capacity related parameters as received signal levels, interference, throughput, and transmit power levels have been studied in order to find out the optimal solution for HSDPA in UMTS. The results clearly show that pico cells and distributed antenna system have outstanding performance in indoor propagation channel compared to radiating cable. In sense of signal quality, pico cell performance is slightly better compared to distributed antenna system. However, measurements with HSDPA indicate that practical capacity of DAS outperforms pico cells. The measurements also show that separation of the antennas is a key capacity related parameter when planning WCDMA based indoor systems.

Nonlinear imaging of nanostructures using beams with binary phase modulation

We demonstrate nonlinear microscopy of oriented nanowires using excitation beams with binary phase modulation. A simple and intuitive optical scheme comprising a spatial light modulator gives us the possibility to control the phase across an incident Hermite-Gaussian beam of order (1,0) (HG10 mode). This technique allows us to gradually vary the spatial distribution of the longitudinal electric fields in the focal volume, as demonstrated by second-harmonic generation from vertically-aligned GaAs nanowires. These results open new opportunities for the full control of polarization in the focal volume to enhance light interaction with nanostructured materials.