铁路GSM-R无线网络时间提前量异常问题研究

Research on Time Advance Anomaly of Railway GSM-R Wireless Network

针对与光纤直放站区段CTCS-3级无线通信超时经常伴随出现的小区切换时间提前量(TA)异常问题,分析了TA基本原理和GSM-R无线网络基站子系统的拓扑结构,计算TA理论值并进行现场测试。目前已知的TA异常问题通常由Handover Access消息发射端引起,通过对空口监测系统的关键技术进行研究,优化和增强了Handover Access消息捕捉功能;同时定义并引入比特偏移量BitShift进行多路径信号TA估算,验证了空口监测系统和基站的TA计算结果一致,解决了因技术手段和方法缺失导致无法分析和定位TA异常现象的问题。

In order to solve the problem of abnormal cell handover time advance(TA) often accompanied by CTCS-3 wireless communication timeout failure in optical fiber repeater section, the basic principle of TA and the topology of GSM-R wireless network base station subsystem are analyzed, and the theoretical value of TA is calculated and field tested. At present, the known TA anomaly problem is caused by the transmitter of the handover access message. Through the research on the key technologies of the air interface monitoring system, the function of capturing the handover access message is optimized and enhanced. At the same time, the variable Bitshift is defined and introduced to estimate the TA of multi-path signals. It is verified that the TA calculation results of the Um interface monitoring system and the base station are consistent, which solves the problem that TA anomalies cannot be analyzed and located due to the lack of technical means and methods.