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Method of railway wireless environment path loss index estimation

A path loss, wireless environment technology, applied in wireless communication, radio wave measurement system, transmission monitoring and other directions, can solve the problem of not necessarily applicable and high cost

Inactive Publication Date: 2009-07-08
BEIJING JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Secondly, Lee's law is a sampling law derived based on the characteristics of low-speed mobile stations in cellular cells, which may not be applicable in the high-speed mobile environment of railways with wide coverage of cells.
Finally, the cost of the actual road survey in the railway mobile environment is higher than that of the general land mobile communication system

Method used

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  • Method of railway wireless environment path loss index estimation
  • Method of railway wireless environment path loss index estimation
  • Method of railway wireless environment path loss index estimation

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0065] Embodiment 1: According to the classical wireless propagation theory, the strong-scale fading of the wireless receiving signal field has a logarithmic linear relationship with the distance, and the slope of the straight line is the path loss index. Since the radial path selection process is omitted, it is necessary to judge whether the railway line satisfies this log-linear relationship. Verify by measuring the timing advance in the report: for the time division system, the timing advance is used to resist signal delay. As the distance between the mobile station and the base station changes, the transceiver gradually instructs the mobile station to send in advance. It varies from 0 to 233 microseconds. Generally, the time advance between stations is V-shaped, and the whole line is zigzag, which means that the train basically moves radially along the base station; if the time advance between stations on the whole line is trapezoidal, it means that the train runs with a l...

Embodiment 2

[0073] Embodiment 2: After receiving the effective measurement report samples, it is necessary to determine the statistical interval through the wedge diffraction model, and then obtain the sampling interval for cubic spline sampling. The process of determining the sampling interval is given as follows:

[0074] Step 1: Determine which wedge diffraction model to apply according to the terrain relief factor defined by the International Union of Railways. If the factor is less than 2, apply the single wedge diffraction model; if the factor is not less than 2, apply the double wedge diffraction model to determine the statistical interval;

[0075] Step 2: If it is a single-wedge diffraction model, parameters such as the height of the single-wedge obstacle, the service frequency of the cell base station, and the average effective distance between the train and the obstacles around the track must be obtained to determine the Fresnel in the single-wedge diffraction model ear diffra...

Embodiment 3

[0081] Embodiment 3: Embodiments 1 and 2 lay the foundation for sample data processing. The data processing flow of embodiment 3 is as Figure 4 shown. The following are several steps to obtain the path loss index by applying the numerical method:

[0082] Step 1: According to the GPS positioning information of the train or the kilometer mark information of other interfaces, store the samples with a number of not less than 5 in an array, and perform strict time alignment operations. Since the interval of GPS positioning information or mileage mark information is longer than the interpolation interval, it is necessary to manually fine-tune the comparison after the general alignment. The comparison criterion is: every 20 sampling points are compared once, and there are many comparison sampling points More than 10, the total deviation is less than 20dB, it can be considered as time aligned;

[0083] Step 2: In order to avoid the phenomenon of high-order ill-conditioned interpo...

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Abstract

A novel method for evaluating the loss index of railway wireless environment path is use in the railway wireless mobile communication system in which the radio wave propagation environment is rather complex. The method is an improvement of the evaluation method for the loss index of land mobile communication system path and is based on wedge-shaped diffraction model and cubic spline interpolation. The method requires the system to provide enough train measurement reporting samples, the time advance of the samples and the distance image take on a V shape, and topographic relief factor is already known. The scheme can effectively reduces the collection cost of evaluation data and selects appropriate evaluation parameter towards different radio wave propagation environment, thus being benefit to reduce computational complexity.

Description

technical field [0001] The invention relates to a method for estimating a railway wireless environment path loss index, which belongs to the field of mobile communication. Background technique [0002] The valuation method of the existing land mobile communication system has the following steps: [0003] Step 1: Determine the cells that need to be evaluated, and determine the coverage of the cells. [0004] Step 2: Draw several concentric circles on the map marked with contour lines within the range with the base station as the center. The larger the range of the cell, the more the number of circles. Select a radial test path in the plot, which should basically maintain a vertical relationship with the circumference of each concentric circle. [0005] Step 3: The vehicle-mounted station conducts multiple measurements in the uplink and downlink directions along the path. The number of measurements is related to the actual needs and the success rate of data collection. Gene...

Claims

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Application Information

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IPC IPC(8): H04W24/08H04W24/10H04B17/00H04B1/707G01S5/02H04B17/318
Inventor 朱刚侯碧翀艾渤钟章队姜丽君周贤伟
Owner BEIJING JIAOTONG UNIV
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