Comparação do sistema celular móvel através do software Netmonitor e Pathloss associado aos métodos de propagação Okumura, Hata e Cost-231

Abstract

The issue addressed in this paper is related to a very important area of telecommunications in the academic and business branch. The area of mobile communications is increasingly present in everyday life of the population and this technology started from the first inventions in the 1830s related to Telecommunications. The principles of electromagnetic waves are part of the means of communication between the parties involved transmitting radio waves from a base station to a mobile station. The waves propagate in the troposphere and reach the receiving antenna through the direct sight line or spread of multipath. The concepts of atmospheric refraction, Raio Terrestre Equivalents and Fresnel Zone are present in the study of the propagation of electromagnetic waves. By refraction, is to change the direction of an incident wave as it passes through a different medium than today. The concept Raio Terrestre Equivalente in the spread is very important and can be decisive in the project study. However, this concept is checked for links that have distance greater than 18 km and links but that will be studied in this thesis have a lower distance of 4 km. The Fresnel Zone is also an important concept in the analysis of electromagnetic wave, to which said region increases with decreasing frequency through wavelength, allowing a greater reach the desired point. This area is analyzed in terms of line-of-sight for full warranty signal through the First Region of Fresnel, which is changed according to the operating frequency. The mobile system is characterized by wireless communication, through a radio base station performs the geographical area covered by sectorized antennas. The cellular system readjustment was important due to the projects that were formerly carried out, as only one transmitter was responsible for cell coverage of a large area and thus limiting the ability to traffic due to not using multiple frequencies in the same geographical space. The purpose of the cellular network is always increase traffic capacity combined with the frequency reuse mechanisms, sectorization and the use of repeater to extend the range. The propagation model in free space occurs when the incident signal from the transmitting antenna has targeted directly towards the receiving antenna. In mobile systems, this occurs only in project design, it is studied the signal quality receiver point to point. After implantation of the cellular system, the mobile communication system is made using the basic propagation mechanisms is the reflection, dispersion and diffraction. The calculation of Signal Received in the mobile station must be related to the azimuth difference between installed antenna and the link made between mobile and base. This difference adds an attenuation in the gain of the transmitting antenna, in addition to the existing elevation angle at the link point to point. Finally, using the proposed propagation models Okumura, Hata and COST-231, the received signals are found by means of the operating frequency. The Google Earth and Pathloss software will help the study of topographic relief in conjunction with the Fresnel Zone according to the frequency in operation. My Coordinates GPS application is responsible for collecting geographical and Netmonitor coordinates the collection will sign Received. The mobile system used in the studies will be the GSM or 2nd generation technology, which through mathematical calculations related to propagation models, we have the approach of calculated values with the Receive Signal level collected through the application used by engineers of operators telecommunications. The Netmonitor application is validated by different wireless devices in conjunction with the spectrum analyzer. Thus allowing the use for the planned tests. The tests will begin in the Campus UFU in Patos de Minas-MG with cellular links have distance greater than 1 km. In this test will use the model of spreading Okumura, Hata and COST-231 in order to identify which model approaches the values collected by Netmonitor. In sequence, the study will be conducted in geographic areas that carry links with distances less than 1 km away. This is because the aforementioned propagation models can not be used within a distance range mentioned above and we will take to the study of the behavior of each link. The tests will begin in the Campus UFU in Patos de Minas-MG in sequence in two central regions of the same city and finally in Uberlândia, MG. Associated with these tests will be studied beyond Okumura propagation models, Hata and COST- 231, also Recommendation 1411-7. In short, the objective of this thesis is to relate the electromagnetic waves in a cellular system, which spread through existing software and models to show the truth on your application and thus analyze the most accurate method in relation to Netmonitor. Furthermore, also be used for studies where the propagation model is limited relative to the distance between the link and the mobile radio base. Associated with the mobile communication studies, extend the concepts and ideas for further work in the field of antennas and propagation and microwave links, in order to improve the proposed propagation models.