摘要(英) |
With the recent advances in low earth orbit (LEO) constellation, satellite communication (SATCOM) has been included in Non-Terrestrial Network (NTN) and recognized as a promising solution to extend services to unserved area in 5G networks. 3GPP has also considered to develop NR-based NTN, however, part of NR functions should be re-worked duo to SATCOM inherent characteristics. In NR-based NTN, user equipments (UEs) are anticipated to be GNSS-enabled in NTN scenarios in NR Rel-17. Based on the aforementioned features, we propose three novel RACH Occasions (RO) patterns for LEO-NTN.
Though user terminals are assumed to have location information, we design RO patterns with backward compatibility, namely, users who is not aware of its own location are also considered. For UEs with or without GNSS capability (G-UE or nG-UE), we propose to schedule their RO separately, G-RO for G-UE, nG-RO for nG-UE. In this work, we propose three RO patterns that could be flexibly configured by the network. Specifically, scheduling G-RO and nG-RO with same periodicity, we propose RO pair, contrarily with different periodicity, we propose overlapped RO and non-overlapped RO.
To validate the effectiveness of proposed RO patterns, we review the preamble transmission delays through computer simulation. Advantages of scheduling G-RO and nG-RO separately are two-fold. Firstly, simulation results show that average delay of successful preamble transmission for all UEs is reduced. Secondly, nG-UEs are relatively more insusceptible to expected increment of G-UE number in the future. Moreover, we investigate the performance of overlapped RO with different preamble division ratio. |
參考文獻 |
[1] F. Rinaldi et al., "Non-Terrestrial Networks in 5G & Beyond: A Survey," in IEEE Access, vol. 8, pp. 165178-165200, 2020
[2] Inigo del Portillo, Bruce G. Cameron, Edward F. Crawley, “A technical comparison of three low earth orbit satellite constellation systems to provide global broadband,” Acta Astronautica, Volume 159, 2019, Pages 123-135
[3] Nils Pachler, Inigo del Portillo, Edward F. Crawley, Bruce G. Cameron, “An Updated Comparison of Four Low Earth Orbit Satellite Constellation Systems to Provide Global Broadband,” Acta Astronautica, 2019
[4] Study on New Radio (NR) to Support Non-Terrestrial Networks, 3GPP TR 38.811, Release 15, Oct. 2019.
[5] Solutions for NR to Support Non-Terrestrial Networks (NTN), 3GPP TR 38.821, Release 16, Jan. 2020.
[6] Lin, Xingqin, et al. "5G from Space: An Overview of 3GPP Non-Terrestrial Networks." arXiv preprint arXiv:2103.09156 (2021).
[7] M. Series, “IMT vision - Framework and overall objectives of the future development of IMT for 2020 and beyond,” Recommendation ITU, pp. 2083-0, 2015.
[8] Study on using satellite access in 5G, 3GPP TR 22.822, V16.0.0, August 2018.
[9] “NG-RAN; Architecture Description,” 3GPP TS 38.401, v16.5.0 April 2021
[10] “NR and NG-RAN Overall description,” 3GPP TS 38.300, v16.5.0 March 2021
[11] “Medium Access Control (MAC) protocol specification,”3GPP TS 38.321, V16.4.0, Mar. 2021
[12] “Physical layer procedures for control,” 3GPP TS 38.213, V16.2.0, Jun. 2020.
[13] “NR; Requirements for support of radio resource management,” 3GPP TS 38.133, v16.7.0, April 2021
[14] “Physical channels and modulation,” 3GPP TS 38.211, v16.5.0, Mar. 2021.
[15] H. Saarnisaari, A. O. Laiyemo and C. H. M. de Lima, "Random Access Process Analysis of 5G New Radio Based Satellite Links," 2019 IEEE 2nd 5G World Forum (5GWF), 2019, pp. 654-658
[16] T. Chen, W. Wang, R. Ding, G. Seco-Granados, L. You and X. Gao, "Location-Based Timing Advance Estimation for 5G Integrated LEO Satellite Communications," GLOBECOM 2020 - 2020 IEEE Global Communications Conference, 2020, pp. 1-6
[17] L. Zhen, A. K. Bashir, K. Yu, Y. D. Al-Otaibi, C. H. Foh and P. Xiao, "Energy-Efficient Random Access for LEO Satellite-Assisted 6G Internet of Remote Things," in IEEE Internet of Things Journal, vol. 8, no. 7, pp. 5114-5128, 1 April1, 2021
[18] L. Zhen, T. Sun, G. Lu, K. Yu and R. Ding, "Preamble Design and Detection for 5G Enabled Satellite Random Access," in IEEE Access, vol. 8, pp. 49873-49884, 2020
[19] J. Bai and G. Ren, "Adaptive Packet-Length Assisted Random Access Scheme in LEO Satellite Network," in IEEE Access, vol. 7, pp. 68250-68259, 2019
[20] ITU-R Document IMT-2020 Document 5D/3-E “Initial Evaluation Report from ATIS WTSC IMT-2020 Evaluation Group for 3GPP Proponent Submissions of SRIT (DOC. IMT-2020/13) & RIT (DOC. IMT-2020/14)” Nov, 2019 |