Abstract: In daily CTCS-3 (C3 for short) wireless timeout analysis, some faults cannot be accurately located and analyzed due to the incompletion of existing monitoring methods, resulting in many cases where the analysis results are unknown. In order to accurately analyze C3 wireless timeout caused by the abnormal CSD link between the core network (MSC) and BTS, such as frame reverse sequence, frame jump, single pass, etc. It is necessary to enable C3 service monitoring to completely monitor network signaling and related service data of each interface between base station and MSC. Taking a certain high-speed railway train as an example, this paper accurately locates the C3 wireless link timeout cause by adding monitoring module of interface monitoring system, comparing and analyzing the service data. It provides a reference to optimize GSM-R wireless network and overcome the shortage of equipment hardware.

Key words: C3 interface monitoring, data monitoring, FRMR, C3 wireless timeout

摘要： 在日常CTCS-3（简称C3）无线超时分析工作中，由于既有监测手段不全，导致部分故障无法准确定位、分析，从而出现很多分析结论为原因不明的情况。为准确分析核心网（MSC）至基站（BTS）之间的帧逆序、帧跳变、单通等电路交换数据业务（Circuit Switched Data，CSD）链路异常造成的C3无线超时异常，需要启用C3业务监测来完整监测基站至MSC之间各接口的网络信令及相关业务数据。以管内高铁某趟列车因逆序帧触发帧拒绝（FRMR）导致列车C3无线超时为例，通过加装接口监测系统业务监测模块，进行数据比对、分析，从而准确定位C3无线链接超时原因，为后续GSM-R无线网络优化及设备硬件克缺提供了一定借鉴意义。

关键词: C3接口监测, 业务监测, 帧拒绝, C3无线超时