铁路时间同步网延迟不对称补偿方案  

Delay Asymmetry Compensation Scheme of Railway Time Synchronization Network

作　　者：张友鹏[1] 曹建荣 兰丽[2,3] Zhang Youpeng;Cao Jianrong;Lan Li(School of Automatic&Electrical Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China;School of Electronic&Information Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China;Key Laboratory of Opt-Electronic Technology and Intelligent Control,Ministry of Education,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China)

机构地区：[1]兰州交通大学自动化与电气工程学院,甘肃兰州730070 [2]兰州交通大学电子信息工程学院,甘肃兰州730070 [3]兰州交通大学光电技术与智能控制教育部重点实验室,甘肃兰州730070

出　　处：《激光与光电子学进展》2021年第7期139-148,共10页Laser & Optoelectronics Progress

基　　金：中国铁路总公司科技研究开发计划课题资助项目(2015X007-H);光电技术与智能控制教育部重点实验室(兰州交通大学)开放课題(KFKT2018-12);甘肃省科技计划资助项目(20JR10RA218)。

摘　　要：针对铁路时间同步网中上下行链路延迟不一致的问题,提出一种基于改进实时计算数据包排队延迟(ERTCQD)算法的补偿方案。该方案以传输链路时延为依据,得到铁路时间同步网时钟模型;考虑实时计算数据包排队延迟算法中时钟频差计算参数难以获得且时钟频差会导致延迟随时间线性偏移,通过计算线性时钟频差改进该计算方法,并通过求解排队延迟最小数据包估算出排队延迟,最后将该排队延迟引入时钟模型,得到一种新的时钟偏差估计方式,并以此改善延迟不对称导致的对时精度下降问题。研究结果表明:ERTCQD算法的精度更高,平均误差为0.22 ms,基于该方案的补偿效果良好,相比于补偿前,该方案将时钟偏差误差降低了73.2%,链路延迟不对称则降低94.2%。该方案明显提升对时精度,为解决铁路时间同步网延迟不对称提供参考。Aiming at the problem of inconsistent delay of the uplink and downlink in a railway time synchronization network,a compensation scheme based on the enhanced algorithm for real-time calculation of data package queuing delay(ERTCQD)is proposed in this work.First,based on the transmission link delay,the clock model of a railway time synchronization network is obtained.Second,considering that the calculation parameters of clock frequency difference in the real-time calculation algorithm of data package queuing delay are difficult to obtain and the clock frequency difference will lead to linear shift of delay with time,the calculation method is improved by calculating the linear clock frequency difference,and the queuing delay is estimated by solving the queuing delay minimum data package.Finally,the queuing delay is introduced into the clock model,and a new clock offset estimation method is obtained,which can improve the time accuracy degradation caused by delay asymmetry.The results show that:the ERTCQD algorithm has higher accuracy,and the average error is 0.22 ms.The compensation effect of this scheme is good.Compared with results before compensation,the clock offset error is reduced by 73.2%,and the link delay asymmetry is reduced by 94.2%.The proposed scheme significantly improves the timing accuracy and provides a new reference for solving the delay asymmetry of the railway time synchronization network.

关 键 词：光通信 铁路时间同步网 改进实时计算数据包排队延迟算法 延迟不对称补偿 排队延迟 

分 类 号：U285.5[交通运输工程—交通信息工程及控制]