高铁VoLTE测试中基于小区方位角的定位方法

Vo LTE测试对优化高速铁路(简称高铁) 4G网络性能与评估高铁舒适度具有重要意义。针对高铁4G高清语音Vo LTE测试中的GPS信号缺失问题,基于小区方位角和高铁地图,计算小区天线主瓣方向射线与高铁轨道曲线的交点,根据相邻基站的覆盖切换交点求出高铁沿线每个基站的覆盖范围;在该覆盖范围内,以铁路轨道离散化的经纬度点数与测试终端RSRP采样点数的比值作为插值周期,均匀插值等量、缺失的轨道经纬度信息,实现对测试终端的定位。通过对兰新高铁不同地形的现场测试和仿真分析,结果表明:该方法在GPS信号缺失情形下能够获取测试终端的位置信息且定位精度约8 m,满足了高铁Vo LTE测试数据分析对位置信息的需求。

Positioning Method Based on Cell Azimuth in VoLTE Test for High-speed Railway

VoLTE test is very important for optimizing the performance of 4G network of high-speed railway(HSR)and evaluate the comfort level of HSR.In respect of the lack of GPS signal in high-speed 4G HD VoLTE test,the intersection of the cell antenna’s main lobe directional beam and the HSR trajectory was calculated based on the cell azimuth and the HSR map.According to the coverage switch intersection of adjacent base stations,the coverage areas of each base station were found out.Within the coverage areas,the ratio of longitude and latitude points of railway track discretization to RSRP sampling points of test terminal was used as interpolation period.When GPS was missing from the test,the latitude and longitude information of the equal orbit was uniformly interpolated to locate the test terminal.Through the test and simulation analysis of different topographies of Lanzhou-Urumqi HSR,the results show that the positioning accuracy is less than 10m by this method in the absence of test terminal GPS signal,which meets the requirement of location information for the HSR VoLTE test data analysis.