随着非静止轨道（non-geostationary orbit，NGSO）卫星系统数量的增加，使用相同频率的NGSO卫星系统之间相互干扰的问题日益凸显。由于NGSO卫星系统干扰场景具有卫星数目众多和相对关系时变等特点，因此针对静止轨道（geostationary orbit，GSO）卫星系统间干扰的传统仿真方法和评价体系不再适用。该文根据国际电信联盟相关的规则和建议，建立了NGSO卫星系统干扰分析数学模型，提出了卫星星座干扰分析的链路夹角概率分析方法；针对NGSO卫星数目众多和时空关系时变等复杂特征给出了全球场景下NGSO全星座干扰分析的方案，提出了星座间产生有害干扰的概率计算方法和星座可用性指标。在实际卫星网络资料的基础上，以OneWeb系统和O3b系统为例，计算了卫星系统间干扰保护的链路夹角限值范围，并给出了全球范围内卫星链路夹角、干扰状态及可用性比例的概率分布结果，为NGSO星座干扰分析提供了一种可参考的手段。
With the increase in the number of non-geostationary orbit (NGSO) satellite systems, the interference between NGSO satellite systems using the same frequency has become increasingly prominent. Because of the large number and time-vary relative motion of NGSO systems, the traditional interference analysis methods and evaluation index, which are aiming for geostationary orbit (GSO) satellite systems, are no longer suitable for NGSO scene. Based on the relevant rules and recommendations of the International Telecommunication Union, this paper establishes a mathematical model of the interference analysis for non-geostationary satellite systems, and proposes a link angle probabilistic analysis method for satellite constellation interference analysis. Aiming at the complicated features such as the large number of satellites consisting of NGSO constellations and the changing temporal and spatial relationship, the scheme of NGSO constellation global interference analysis is given. The probability calculation method of harmful interference between satellite constellations and the index of satellite constellation usability are proposed. On the basis of the actual satellite network data, taking OneWeb system and O3b system as an example, the range of the link angle of the interference protection between the satellite systems is calculated. The angle of the satellite link, the interference state and the probability distribution of the availability ratio on a global scale are given, provides a means for NGSO constellation interference analysis.
[1] PARK C S, KANG C G, CHOI Y S, et al. Interference analysis of geostationary satellite networks in the presence of moving non-geostationary satellites[C]//Proceedings of the 20102nd International Conference on Information Technology Convergence and Services. Cebu, Phillippines:IEEE, 2010:1-5.
[2] KOBAYASHI H, SHINONAGA H, ARAKI N, et al. Study on interference between non-GSO MSS gateway station and GSO FSS earth station under reverse band operation[C]//Proceedings of the 10th International Conference on Digital Satellite Communications. Brighton, UK:IET, 1995:282-289.
[3] GAM H, OH D S, AHN D S. Effective method to assess the impact of interference between non-GSO system and fixed service[C]//Proceedings of 2009 International Workshop on Satellite and Space Communications. Tuscany, Italy:IEEE, 2009:206-209.
[4] FORTES J M P, MALDONADO J E A. Protection of fixed service receivers from the interference produced by the non-geostationary satellites in a fixed satellite service network:A statistical interference analysis[J]. International Journal of Satellite Communications, 2002, 20(1):15-27.
[5] FORTES J M P, SAMPAIO-NETO R, MALDONADO J E A. An analytical method for assessing interference in interference environments involving NGSO satellite networks[J]. International Journal of Satellite Communications, 1999, 17(6):399-419.
[6] ITU-R. Analytical method for estimating interference between non-geostationary mobile-satellite feeder links and geostationary fixed-satellite networks operating co-frequency and codirectionally:ITU-R S.1324[S]. Geneva:ITU, 1997.
[7] ITU-R. Artical 21 in radio regulations[R]. Geneva:ITU, 2016.
[8] 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.
[9] VATALARO F, CORAZZA G E, CAINI C, et al. Analysis of LEO, MEO, and GEO global mobile satellite systems in the presence of interference and fading[J]. IEEE Journal on Selected Areas in Communications, 1995, 13(2):291-300.
[10] DESLANDES V, TRONC J, BEYLOT A L. Analysis of interference issues in integrated satellite and terrestrial mobile systems[C]//Proceedings of the 11th Signal Processing for Space Advanced Satellite Multimedia Systems Conference. Cagliari, Italy:IEEE, 2010:256-261.
[11] ITU-R. Coordination of the L5 satellite network in IFIC2809[DB]. (2015-08-12)[2017-05-10]. https://www.itu.int/sns/ific61/ific2809.zip.
[12] ITU-R. Coordination of the O3b-A satellite network in IFIC2644[DB]. (2009-05-19)[2017-05-10]. https://www.itu.int/sns/ific6/ific2644.zip.
[13] ITU-R. Coordination of the O3b-B satellite network in IFIC2693[DB]. (2011-05-03)[2017-05-10]. https://www.itu.int/sns/ific61/ific2693.zip.
[14] ITU-R. Apportionment of the allowable error performance degradations to fixed-satellite service (FSS) hypothetical reference digital paths arising from time invariant interference for systems operating below 30 GHz:ITU-R S.1432-1[S]. Geneva:ITU, 2006.
