[1] Qu B. Introduction of railway time synchronization network[J]. Railway Signalling & Communication Engineering, 7, 43-45(2010).

[2] Zhang Y P, Li X, Lan L et al. Research on big-data-based anomaly detection system of railway time synchronization network‍[J]. Journal of Railway Science and Engineering, 17, 306-313(2020).

[3] Zhan X F. Design of time synchronization system for railway administration‍[J]. Railway Signalling & Communication Engineering, 14, 29-31(2017).

[6] Riesch C, Marinescu C, Rudigier M et al. Measurement of egress and ingress delays of PTP clocks[C], 113-118(2013).

[7] Chen W, Gao X J, Li D D et al. Improved method of PTP protocol based on grey prediction[J]. Systems Engineering and Electronics, 39, 1842-1848(2017).

[8] Chaloupka Z, Alsindi N, Aweya J et al. Clock synchronization over communication paths with queue-induced delay asymmetries[J]. IEEE Communications Letters, 18, 1551-1554(2014).

[9] Lv S, Lu Y M, Ji Y F et al. An enhanced IEEE 1588 time synchronization for asymmetric communication link in packet transport network[J]. IEEE Communications Letters, 14, 764-766(2010).

[10] Karthik A K, Blum R S. Robust clock skew and offset estimation for IEEE 1588 in the presence of unexpected deterministic path delay asymmetries[J]. IEEE Transactions on Communications, 68, 5102-5119(2020).

[11] Chen L, Zhu T L, Liu F et al. Packet delay estimation with minimum queue waiting in asymmetric network[J]. Journal of Shanghai Jiao Tong University, 48, 1394-1399(2014).

[12] Karthik A K, Blum R S. Estimation theory-based robust phase offset determination in presence of possible path asymmetries[J]. IEEE Transactions on Communications, 66, 1624-1635(2018).

[13] Liu M Y. Research and implementation of one way network oriented time delay measurement[D], 19-22(2018).

[14] Liang Y F, Xu J N, Wu M et al. Research progress on optical fiber time-frequency synchronization technology[J]. Laser & Optoelectronics Progress, 57, 050004(2020).

[15] Gu W X, Yu S Z. Novel approach to measure and estimate one-way queuing delay without clock synchronization[J]. Journal on Communications, 28, 104-111, 118(2007).

[16] Wu Z G, Liu M Y. One-way delay measurement method based on clock synchronization[J]. Journal of Southeast University (Natural Science Edition), 47, 108-112(2017).

[17] Li W W, Zhang D F, Zeng B et al. Queuing analysis and simulation of the measurability of end-to-end minimum packet delay[J]. Journal of Hunan University (Natural Sciences), 34, 73-77(2007).

[18] Qian C, Xu X, Mei J et al. Communication path queue-induced asymmetry algorithm for clock synchronization on IEEE 1588[J]. Power System Technology, 39, 3622-3626(2015).

[19] Wang H B, Lin Y, Jin Y H et al. A new approach for removing clock skew and resets from one-way delay measurement[J]. Acta Electronica Sinica, 33, 584-589(2005).

[20] Li Y Z, Wang M G, Guo Y X et al. Dual-polarization carrier phase recovery algorithm based on simplified extended Kalman filter[J]. Acta Optica Sinica, 39, 1106005(2019).

[21] Ma S X, Liu C T, Li H C et al. Feature extraction based on linear embedding and tensor manifold for hyperspectral image[J]. Acta Optica Sinica, 39, 0412001(2019).

[22] Freris N M, Graham S R, Kumar P R et al. Fundamental limits on synchronizing clocks over networks[J]. IEEE Transactions on Automatic Control, 56, 1352-1364(2011).

[23] Chen M. Research and implementation of network time synchronization system base on network time protocol[D], 13-22(2005).

[24] Mills D L. Internet time synchronization: the network time protocol[J]. IEEE Transactions on Communications, 39, 1482-1493(1991).