Coal mine underground wireless transmission analysis method

At present, the design and plan of the mine mobile communication system and the personnel and vehicle positioning system mainly depend on experience and field test. There are some problems such as heavy workload, difficult optimization of the layout of the communication base station and positioning substation and the antenna setting, etc. In order to promote the application of underground wireless transmission analysis methods in the design and plan of mine mobile communication system, personnel and vehicle positioning system, as well as the layout of the communication base station and positioning substation and the antenna setting, the application scope, advantage and disadvantages of different underground wireless transmission analysis methods are analyzed. ① Parabolic equation method has the advantages of simple algorithm and small computing memory resources. But it is not suitable for analyzing the influence of roadway undulation, support, longitudinal conductor and transverse conductor on wireless transmission attenuation in mines. ② The finite-difference time-domain method has a wide range of applications. But it requires a larger amount of computing memory resources. When analyzing the influence of roadway bending, undulation, irregular section shape and other factors on the wireless transmission attenuation in mines, the error is large. ③ The finite element method is the most widely used. The tetrahedral mesh can be used. Compared with the hexahedral mesh used in the finite difference time domain method, it can fit irregularly structured roadways better. But it requires the largest computing memory resources. The existing high-grade server memory capacity is difficult to meet the demand. It is suitable for small section, short distance, and low-frequency coal mine underground wireless transmission analysis. ④ The ray tracing method has the advantages of simple algorithm and minimum computing memory resources. But the application range is small. The ray tracing method is only suitable for analyzing the influence of factors such as high-frequency wireless working frequency, section shape, surrounding rock medium, and roadway bending on the wireless transmission attenuation of the mine. The ray tracing method cannot analyze the influence of factors such as different positions of an antenna on a roadway section, roadway branches, roadway undulation, supports, longitudinal conductor and transverse conductor on the wireless transmission attenuation of the mine. When analyzing the influence of low frequency band wireless operating frequency on the wireless transmission attenuation of the mine, the error is large. ⑤ The statistical analysis method has the advantage of simplicity and ease of use, but it requires a large amount of measured data. The coal mine underground roadway has a plurality of types, complex environment, branches, bends, and undulation. It has large measurement workload and low efficiency. It is difficult to measure the wireless transmission attenuation data under the conditions of different roadways and supports in the coal mine underground. It is difficult to analyze the wireless working frequency, the different positions of the antenna on the roadway section, the area and the shape of the roadway section, the bend of the roadway, the branch of the roadway, the undulation of the roadway, the surrounding rock medium, the supports, the longitudinal conductor and transverse conductor on wireless transmission attenuation of the mine.oadway, the surrounding rock medium, the supports, the longitudinal conductors, and transverse conductor on wireless transmission attenuation of the mine.