This Master thesis deals with wave propagation and starts with wave propagation basics. It briefly presents the theory for the diffraction over terrain obstacles and describes two different path loss models, the Hata model and a FFT-based model. The significance of this paper is that it gives the simulation results for the models mentioned above and presents a comparison between the results obtained from an empirical formula and the FFT-model. The comparison shows that the approach based on Fast Fourier Transform is good enough for prediction of the path loss and that it is a time efficient method.

The objective of this thesis is to design a mobile positioning system on the premise that low system complexity and less modification of components of Mobile Communication System to improve the possibility that adopted by service provider. Therefore we propose a Mobile Service Positioning System for Cellular Mobile Communication System. It works based on location information of base station and mutual relations of signal strength of base stations received by mobile phone. We adjust the environment factor upon different path loss caused by different geographical feature. And then we perform EWVD Algorithm to estimate the area where mobile phone locates in. Eventually, we obtain a Mobile Positioning System which has properties: lower building cost, smaller locating area, and faster response time.

[pt] O transporte de voz continua crescendo nos sistemas de comunicações atuais, progredindo de um serviço específico numa determinada localização para um serviço mais pessoal, com a grande maioria das pessoas possuindo um telefone móvel. O transporte de dados é a área de maior desenvolvimento que, através da introdução do IP (acesso Internet), irá permitir diversas oportunidades de negócios. Transmissão de dados e outras aplicações serão a chave para novos rendimentos. Diversos serviços, principalmente para transporte IP, têm sido desenvolvidos, operando em freqüências mais altas que a de sistemas celulares atuais. Dentre elas existe uma aplicação específica da banda de 3,5 GHz para sistemas FWA (Fixed Wireless Access). Neste sentido, destaca-se a importância do estudo do comportamento de um sinal eletromagnético na freqüência de 3,5 GHz principalmente em ambientes urbanos. Este estudo foi desenvolvido neste trabalho e constituiu-se de uma campanha de medições de intensidade de campo nesta freqüência específica realizada em dois ambientes de características diferentes dentro da cidade do Rio de Janeiro. Um laboratório de medidas móveis foi montado e o nível de sinal recebido de uma transmissão fixa foi medido em diversas ruas destes ambientes. Resultados de perda de percurso em função da distancia foram obtidos e comparados com os modelos mais usuais de predição de cobertura. Além disto as características de variabilidade do nível de sinal recebido foram também medidas e suas estatísticas comparadas com distribuições de probabilidade conhecidas. Resultados obtidos no trabalho sugerem novos modelos de predição de perda de percurso e novas distribuições estatísticas principalmente para parâmetros sistêmicos como taxa de cruzamento de nível e duração média de desvanecimento. / [en] Voice transport stills emerging in modern communication systems, going ahead from a specific located service to a more personal, with most of people having a mobile phone. Data transport is the development area that, through the Internet Protocol (IP), will allow a lot of opportunities on the business market. Data and the new applications that will emerge will be the key to new yields in wireless communications. A lot of data transport services through IP are being developed, operating on a frequency band higher than the one used by the existent cellular mobile systems. Actually there are a lot of emerging FWA (Fixed Wireless Access) services in the 3.5 GHz band with support to IP. Then, the study of the behaviour of an electromagnetic signal in 3.5 GHz is a very important issue because new and important applications are emerging and being developed in this band. In order to carry out this task, a fixed to mobile link was assembled and a lot of experimental work was performed on two different sites of Rio de Janeiro city. The results presented in this work deal with path- loss measurements for coverage prediction and the study of received signal variability essential on system parameter determination. The results are compared with the most popular empirical and statistical models in the literature. The conclusion of this work suggest that new prediction models for path-loss determination and new distribution functions are needed mainly for systems parameters like level crossing rate (LCR) and average fading duration (AFD). / [es] EL transporte de voz continúa creciendo en los sistemas de comunicaciones actuales, llendo de un servicioo específico en una determinada localización para un servicio más personal, donde la gran mayoría de los individuos posean un teléfono móvil. El transporte de datos es el área en desarrollo que, a través de la introducción del IP (acceso Internet), abrirá diversas oportunidades de negocios. la transmisión de datos y otras aplicaciones serán un punto clave para nuevos rendimientos. Diversos servicios, principalmente para transporte IP, han sido desarrollados, operando en frecuencias más altas que la de sistemas celulares actuales. Dentro de ellas, existe una aplicación específica de la banda de 3,5 GHz para sistemas FWA (Fixed Wireles Acces). En este sentido, es de destacar, la importancia del estudio del comportamiento de una seña eletromagnética en frecuencia de 3,5 GHz principalmente en ambientes urbanos. Este estudio fue desarrollado en el marco de este trabajo y está constituido por una campaña de mediciones de intensidad de campo en esta frecuencia específica realizada en dos ambientes de características diferentes en la cidad del Rio de Janeiro. Se montó un laboratorio de medidas móviles y el nivel de la señal recibido de una transmisión fija fue medido en diversas calles de estos ambientes. Se obtuvieron resultados de pérdida de recorrido en función de la distancia. Éstos fueron comparados con los modelos más usuales de predicción de cobertura. Se midieron además, las características de variabilidad del nivel de la señal recibida y sus estadísticas se fueron comparadas con las distribuciones de probabilidad conocidas. Los resultados obtenidos en este trabajo sugieren nuevos modelos de predicción de pérdida de recorrido y nuevas distribuciones estadísticas principalmente para parámetros sistémicos como tasa de cruzamiento de nível y duración media de desvanecimiento.

The invention of closed circuit television (CCTV) has initiated a new trend in high security by video surveillance. More recently, CCTV cameras have been incorporating wireless LAN technology for data transfer purposes by using on chip memory storage until the time of update. In this thesis, short range communication such as Bluetooth low energy (Bluetooth smart) is used in order to perform simple I/O applications. The two important components of the project are the camera and the Bluetooth module box. An external antenna is designed for the connectivity box and the operating range of the box is deduced by using link budget. The blue cool connectivity box is assessed by defining the capabilities of the box, i.e., simple I/O operations. Field test measurements for the designed antenna provide optimum communication range. The thesis also reviews software simulation tools that are essential for antenna design and path loss modelling. The efficiency of simulated measurements versus real-time measurements are also assessed. The primary target of the thesis is to detail the design of a cost-effective antenna based on link budget calculations and perform basic I/O tasks wirelessly between the blue cool connectivity box and the camera. It is concluded that in future works, advanced operations can be added on to the existing model. It is also suggested that a model for multi floor communication can be designed.

LoRaWAN is a wireless network technology based on the LoRa modulation technology. When planning such a network, it is important to estimate the network’s coverage, which can be done by calculating path loss. To do this, one can utilize empirical models of radio wave propagation. Previous research has investigated the accuracy of such empirical models for LoRa inside cities. However, as the accuracy of these models is heavily dependent on the exact characteristics of the environment, it is of interest to validate these results. In addition, the effect of base station elevation on the models’ accuracy has yet to be researched. Following the problems stated above, the purpose of this study is to investigate the accuracy of empirical models of radio wave propagation for LoRa in an urban environment. More specifically, we investigate the accuracy of the models and the effect of base station elevation on the models’ accuracy. The latter is the main contribution of this study. To perform these investigations, a quantitative experiment was conducted in the city of Jönköping, Sweden. In the experiment a base station was positioned at elevations of 30, 23, and 15m. The path loss was measured from 20 locations around the base station for each level of elevation. The measured path loss was then compared to predictions from three popular empirical models: the Okumura-Hata model, the COST 231-Walfisch-Ikegami model, and the 3GPP UMa NLOS model. Our analysis showed a clear underestimation of the path loss for all models. We conclude that for an environment and setup similar to ours, models underestimate the path loss by approximately 20dB. They can be improved by adding a constant correction value, resulting in a mean absolute error of at least 3,7-5,6dB. We also conclude that the effect of base station elevation varies greatly between different models. The 3GPP model underestimated the path loss equally for all elevations and could therefore easily be improved by a constant correction value. This resulted in a mean absolute error of approximately 4dB for all elevations.

In this thesis it is investigated to what extent it is possible to accurately model path loss in indoor environments using a simple empirical approach. Two kinds of radio access antenna deployments are investigated: 1) standard dipole antennas and 2) leaky cables. For the case of standard dipole antenna deployment, a few well established empirical models are integrated in order to account for the main observed propagation mechanisms. One important propagation mechanism is wave guiding in corridors. It has been shown that a model designed for street microcells (“The recursive model”) combined with the power law model (combined model) well describes this wave guiding propagation. Some inaccuracies have, however, been observed when the direct pathway is dominating. In this master thesis it is therefore investigated if the model accuracy may be improved by integration of the Keenan-Motley and the Devasirvatham model (modified combined model) accounting for loss due to obstructions along the direct pathway. In this work, the primary models used for the case of leaky cable antenna deployments are the Keenan-Motley model (for short distances) and the modified combined model (for large distances). In order to improve and evaluate the modeling, propagation measurements have been carried out at the 2.44 GHz band in an indoor office environment. The measurement data, i.e., the calibrated frequency response of the channel, is obtained using the network analyzer measurement technique by sweeping the frequency over a range of 80 MHz around the center frequency. Hence, the path gain measured in dB-scale is obtained as the difference between the transmitted power and the received power. The combined model and the modified combined model are evaluated and parameterized based on the conducted measurements. The accuracy of the combined model is improved by the implemented modifications. In our case, the standard deviation error is reduced from 5-19 dB to 2-4 dB. Moreover, the measurements show that using leaky cables results in a better coverage in rooms alongside the corridor compared with using dipole antennas. Also the interference into adjacent cells is reduced using leaky cables compared with using dipole antennas.

IEEE 802.11 wireless networking equipment has made it possible to bridge the last mile for new broadband internet service providers. Inexpensive wireless networking equipment and high gain antennas enable high speed internet delivery at a fraction of the cost of installing or upgrading land lines for cable or DSL services. Based on this research, a guide of general practices and procedures is proposed for designing, installing, and maintaining a reliable wireless community area network. Included tests have provided performance results for several types of wireless antennas (including wire grid parabolic dishes, Yagi and Vagi styles, and echo backfire), wireless bridges, and other factors which influence overall signal strength and throughput. Two separate configurations are recommended. The first configuration is based on high reliability, longer distances, and low error rates. The second recommendation is based on lower overall cost, ease of installation, and shorter link distances.

This thesis presents a model to predict signal strength for frequencies between 902 MHz and 28 GHz. The model approximates diffraction using the knife-edge concept and equations proposed by Lee (1985). LOS pathways are calculated using the Bresenham algorithm and the corresponding elevations are obtained from a 30m DEM base map. The base map was generated by the procedure outlined in Rose (2001) and includes building elevations. The effect of Fresnel zones on prediction accuracy is considered. The effect of interpolating elevations along the Bresenham line is also considered. An Inverse Distance Weighting algorithm was used to interpolate the elevations. The accuracy of the model was evaluated using received signal strength data compiled from studies conducted at 902 MHz, 24.12 GHz and 27.525 GHz. In addition to the compiled data, data was also collected for this study at 2.4 GHz. 257 receiver locations were evaluated; 70 samples were Line-of-Sight. The study area incorporates the Virginia Polytechnic Institute and State University campus. Incorporating Fresnel zones, Interpolating elevations and calculating double blockages do not have an effect on the program's overall ability to predict signal strength. However, for obstructed pathways, it is not adequate to simply use path loss as an estimate of signal strength. Accurate estimates of diffraction gain are crucial for obstructed pathways. In addition, examination of the standard deviation for the data sets indicates that the model is independent of frequency. The average error across the frequencies is positively correlated with frequency, indicating that the model predicts signal strength better for higher frequencies. The smaller wavelengths associated with the higher frequencies require a more directional antenna and are therefore less sensitive to multipath interference. In addition, the smaller wavelengths are less able to diffract around buildings and terrain features. / Master of Science

No description available.

No description available.