Interference avoidance strategy for LEO satellite based on transmit beam sidelobe nulling

doi:10.7523/j.ucas.2022.068

Abstract

Abstract: With the rapid development of broadband low-orbit satellite systems, communication frequency bands such as Ku and Ka tend to be saturated gradually, and non-geostationary orbit (NGSO) satellites will inevitably cause interference to geostationary orbit (GSO) satellites operating at the same frequency. At present, a spatial isolation strategy is often adopted to avoid interference. NGSO satellites always produce the strongest interference to the collinear area. Increasing the isolation angle can reduce the interference, but it will greatly lose the coverage of the LEO satellite. This paper proposes an interference avoidance strategy based on sidelobe nulling of the transmit beam. The antenna array is divided into row and column elements by establishing the LEO satellite coordinate system. In the dimension of column elements, the robust LCMV algorithm is used to realize wide nulling. In the dimension of row elements, it is expanded in combination with beam direction, and finally forms a “null band” in the direction of the collinear area. Through simulation analysis, the proposed strategy can effectively reduce the interference avoidance isolation area of LEO satellites while avoiding collinear interference. The algorithm has low complexity and is easy to implement on satellites.

Key words: LEO satellite, interference avoidance, beamforming, sidelobe nulling

CLC Number:

TN927

WANG Haiwang, ZOU Cheng, CHANG Jiachao, SHAO Fengwei, JIANG Quanjiang, LI Guotong. Interference avoidance strategy for LEO satellite based on transmit beam sidelobe nulling[J]. Journal of University of Chinese Academy of Sciences, 2024, 41(4): 541-549.

References

[1] 方芳, 吴明阁. 全球低轨卫星星座发展研究[J]. 飞航导弹, 2020(5): 88-92, 95. DOI:10.16338/j.issn.1009-1319.20190258.
[2] 韩锐, 张磊, 刘珊杉. 典型低轨通信星座系统的确定性干扰分析[J]. 数字通信世界, 2020(9): 60-62. DOI:10.3969/J.ISSN.1672-7274.2020.09.022.
[3] Sharma S K, Chatzinotas S, Ottersten B. Transmit beamforming for spectral coexistence of satellite and terrestrial networks[C]//8th International Conference on Cognitive Radio Oriented Wireless Networks. July 8-10, 2013, Washington, DC, USA. IEEE, 2013:275-281. DOI:10.1109/CROWNCom.2013.6636830.
[4] Zheng Y H, Sun S L, Rong B, et al. Traffic aware power allocation and frequency reuse for green LTE-A heterogeneous networks[C]//2015 IEEE International Conference on Communications. June 8-12, 2015, London, UK. IEEE, 2015:3167-3172. DOI:10.1109/ICC.2015.7248811.
[5] Reed A G, Posen M C J. Interference in the fixed satellite service bands between the feeder-links of networks using nongeostationary satellites and network using geostationary satellites[C]//3rd European Conference on Satellite Communications-ECSC-3, 1993. November 2-4, 1993, Manchester, UK. IET, 1993: 251-256.
[6] Sharma S K, Chatzinotas S, Ottersten B. Cognitive radio techniques for satellite communication systems[C]//2013 IEEE 78th Vehicular Technology Conference. September 2-5, 2013, Las Vegas, NV, USA. IEEE, 2013:1-5. DOI:10.1109/VTCFall.2013.6692139.
[7] 张泓湜, 蒋伯峰. 基于空间隔离的低轨卫星系统频谱共享方法[J]. 北京航空航天大学学报, 2018, 44(9): 1909-1917. DOI:10.13700/j.bh.1001-5965.2017.0732.
[8] ITU Radiocommunication (ITU-R). Simulation methodologies for determining statistics of short-term interference between co-frequency, codirectional non-geostationary-satellite orbit fixed-satellite service systems in circular orbits and other non-geostationary fixed-satellite service systems in circular orbits or geostationary-satellite orbit fixed-satellite service networks[S/OL]. (2003-10-08)[2021-12-18]. https://www.itu.int/rec/R-REC-S.1325-3-200310-I/en.html.
[9] ITU Radiocommunication (ITU-R). Interference mitigation techniques to facilitate coordination between non-geostationary-satellite orbit mobile-satellite service feeder links and geostationary satellite orbit fixed-satellite service networks in the bands 19.3~19.7 GHz and 29.1~29.5 GHz[S/OL]. (1999-11-30)[2021-12-18]. https://www.itu.int/rec/R-REC-S.1419-0-199911-I/en.html.
[10] ITU Radiocommunication (ITU-R). Analytical method to calculate short-term visibility and interference statistics for non-geostationary satellite orbit satellites as seen from a point on the earth’s surface[S/OL]. (2002-03-11)[2021-12-18]. https://www.itu.int/rec/R-REC-S.1257-3-200203-I/en.html.
[11] Sharma S K, Chatzinotas S, Ottersten B. In-line interference mitigation techniques for spectral coexistence of GEO and NGEO satellites[J]. International Journal of Satellite Communications and Networking, 2016, 34(1): 11-39. DOI:10.1002/sat.1090.
[12] ITU Radiocommunication (ITU-R). Radio Regulations[S/OL]. (2020-08-19)[2021-12-18]. https://www.itu.int/pub/R-REG-RR-2020.html.
[13] Park I, Seo C, Ku H. Sidelobe suppression beamforming using tapered amplitude distribution for a microwave power transfer system with a planar array antenna[J]. Journal of Electromagnetic Engineering and Science, 2022, 22(1): 64-73. DOI:10.26866/jees.2022.1.r.62.
[14] ITU Radiocommunication (ITU-R). Functional description to be used in developing software tools for determining conformity of non-geostationary-satellite orbit fixed-satellite service systems or networks with limits contained in Article 22 of the Radio Regulations[S/OL]. (2018-01-15)[2021-12-18]. https://www.itu.int/rec/R-REC-S.1503-3-201801-I/en.html.
[15] Frost O L. An algorithm for linearly constrained adaptive array processing[J]. Proceedings of the IEEE, 1972, 60(8): 926-935. DOI:10.1109/PROC.1972.8817.
[16] ITU Radiocommunication (ITU-R). Reference FSS earth-station radiation patterns for use in interference assessment involving non-GSO satellites in frequency bands between 10.7 GHz and 30 GHz[S/OL]. (2001-02-20)[2021-12-18]. https://www.itu.int/rec/R-REC-S.1428-1-200102-I/en.html.