Time Synchronization between the eNBs in E-UTRAN under the Asymmetric IP Network

Authors: M. Kollar, A. Zieba

Abstract:

In this paper, we present a method for a time synchronization between the two eNodeBs (eNBs) in E-UTRAN (Evolved Universal Terrestrial Radio Access) network. The two eNBs are cooperating in so-called inter eNB CA (Carrier Aggregation) case and connected via asymmetrical IP network. We solve the problem by using broadcasting signals generated in E-UTRAN as synchronization signals. The results show that the time synchronization with the proposed method is possible with the error significantly less than 1 ms which is sufficient considering the time transmission interval is 1 ms in E-UTRAN. This makes this method (with low complexity) more suitable than Network Time Protocol (NTP) in the mobile applications with generated broadcasting signals where time synchronization in asymmetrical network is required.

Keywords: E-UTRAN, IP scheduled throughput, initial burst delay, synchronization, NTP, delay, asymmetric network.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.2643927

References:

[1] T. Gotoh, K. Imamura and A. Kaneko, "Improvement of NTP time offset under the asymmetric network with double packets method," Conference Digest Conference on Precision Electromagnetic Measurements, Ottawa, Ontario, Canada, 2002, pp. 448-449.
[2] D. L. Mills, “Computer Network Time Synchronization: The Network Time Protocol”, CRC Press, 2006.
[3] J. C. Eidson, „Correcting time synchronization inaccuracy caused by asymmetric delay on a communication link”, Patent US7602873, 2009.
[4] J. C. Eidson, „Correcting time synchronization inaccuracy caused by asymmetric delay on a communication link”, Patent JP4922750, 2012.
[5] “X2 general aspects and principles”, 3GPP TS 36.420 V9.0.0, 2009.
[6] M. Bhardwaj, L. Paruchuri and S. Shandilya, "Network monitoring in LTE small cell environment," 2015 International Conference on Advanced Computing and Communication Systems, Coimbatore, 2015, pp. 1-5.
[7] R. Prasad, C. Dovrolis, M. Murray and K. Claffy, "Bandwidth estimation: metrics, measurement techniques, and tools," in IEEE Network, vol. 17, no. 6, pp. 27-35, Nov.-Dec. 2003.
[8] E. Dahlman, S. Parkvall and J. Skold “4G: LTE/LTE-Advanced for Mobile Broadband (Second Edition)”, Academic Press, 2013, p.544.
[9] “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification”, 3GPP TS 36.331 V14.5.1, 2018.
[10] “Evolved Universal Terrestrial Radio Access (E-UTRA); Layer 2 - Measurements”, 3GPP TS 36.314 V14.0.0, 2017.