Quantitative Research Of Communication Signals Penetrate Attenuation Under Urban Environment

With the development of technology, urbanization has been speeded and developed rapidly and drastically.urban airspace of the electromagnetic environment is more complex.Communication signals in space transport mechanisms, including direct, transmission, reflection, diffraction, Consequently, attenuations of communication signals includes direct loss, transmission loss, reflection loss, diffraction loss.In urban environments in the next wireless communications, communication signals through obstructions will occur when the reflection and refraction, so that the signal attenuation, barrier attenuation of the signal transmission is a measure of the quality of an important aspect of communication. As people of the communication quality requirements have become more sophisticated, urban environmental problems in the communication signal attenuation more and more attention. This article aims to study the urban environment in the communication signal transmission loss through the building wall.In this paper, the subject is based on the urban environment, communication signal attenuation of quantitative research, first of all,through the electromagnetic environment of the urban traffic signal and surface features in environmental analysis to determine the type of the detected objects measured signal frequency range. Signal attenuation due to obstructions on the size of the main is determined by its size and the equivalent electrical parameters to determine the equivalent electrical parameters of the change in the transmission of communication signals play an important attenuation of the impact, this article describes the field measurement of the equivalent electrical parameters of the building Several methods, focusing on the use of free-space measurement method to measure the transmission attenuation of communication signals.A measurement system based on free-space law was set up.Field surveys of communication signals were conducted of which frequencies are between 30KHz and 3GHz when penetrating obstacles such as buildings.according to the frequency of the different options correspond to antenna measurements, were aimed at two kinds of different densities of buildings of reinforced walls, glass curtain walls, the woods field measurements carried out.The article details the finite-difference time-domain basic principles and boundary conditions and numerical stability issues, and the use of finite-difference time-domain based on difference method XFDTD software build and the actual measurement environment similar to that of the electromagnetic model, through program design and right software parameter settings for the computer simulation and briefly discussed the simulation of key parameters in the process of setting the problem.Then,by transmission to measure wave and open comparison of data calculation, arrived at a different frequency of the transmission coefficient of the wall of the building while using the weighted method to calculate the equivalent dielectric constant of the wall.Using the above fixed-frequency transmission coefficients and the equivalent combination of Fresnel formula for dielectric constant of the frequency inversion of the equivalent conductivity of the building walls and other obstacles come in different frequencies of the equivalent conductivity of,by curve fitting to map out changes in the conductivity versus frequency curve.