BDSec:Security Authentication Protocol for BeiDou-Ⅱ Civil Navigation Message

Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.

广播星历旋转误差对低轨星载BDS-3/GPS实时精密定轨影响分析

基于LT-01A卫星星载BDS-3/GPS观测值进行了星载实时精密定轨研究,并重点分析了广播星历旋转误差对实时定轨精度的影响。通过赫尔默特转换评估了所选时段内GPS和BDS-3广播星历轨道旋转误差,显示BDS-3广播星历旋转误差可达-8.7 mas,平均量级较GPS大约2.5倍。BDS-3广播星历经旋转改正后,轨道切向、法向均方根(RMS)误差从25 cm左右提升至10 cm量级,提升幅度超过50%。因此,基于星载BDS-3以及BDS-3/GPS联合的实时定轨精度受BDS-3星历旋转误差影响严重,且主要作用于切向和法向。经过旋转改正后,单独BDS-3实时定轨在切向、法向、径向RMS分别为21.0 cm、10.7 cm及11.2 cm,其切向和法向精度比改正前分别提升15.0%和31.8%;BDS-3与GPS联合定轨进一步提升切向精度至19.4 cm。得益于BDS-3广播星历较高的精度,单BDS-3以及BDS-3/GPS联合的实时定轨在旋转改正前的三维RMS分别为31.9 cm和29.2 cm,较单GPS实时定轨分别提升9.1%和16.8%;添加旋转改正后,其定轨精度分别提升至26.7 cm和25.0 cm,较单GPS实时定轨分别提升22.6%和27.5%。

基于Hatch滤波的改进矩阵变换法在BDS多频模糊度解算中的应用

长基线条件下,空间相关性弱,电离层延迟残差和噪声影响变大,致使矩阵变换法模糊度解算过程中,窄巷组合受噪声影响大,单历元模糊度解算成功率低。因此,削弱电离层残差及噪声影响可以一定程度提高模糊度解算成功率。本文在分析矩阵变换算法基础上,利用Hatch滤波有效抑制伪距测量噪声和多径效应特点,结合弱电离层、低噪声的载波组合,通过相位平滑伪距代替组合伪距值参与解算,从而削弱电离层残差及观测噪声影响。通过实测数据分析,本文算法可有效提高矩阵变换法模糊度解算成功率。

Data-Driven Heuristic Assisted Memetic Algorithm for Efficient Inter-Satellite Link Scheduling in the BeiDou Navigation Satellite System

Inter-satellite link(ISL)scheduling is required by the BeiDou Navigation Satellite System(BDS)to guarantee the system ranging and communication performance.In the BDS,a great number of ISL scheduling instances must be addressed every day,which will certainly spend a lot of time via normal metaheuristics and hardly meet the quick-response requirements that often occur in real-world applications.To address the dual requirements of normal and quick-response ISL schedulings,a data-driven heuristic assisted memetic algorithm(DHMA)is proposed in this paper,which includes a high-performance memetic algorithm(MA)and a data-driven heuristic.In normal situations,the high-performance MA that hybridizes parallelism,competition,and evolution strategies is performed for high-quality ISL scheduling solutions over time.When in quick-response situations,the data-driven heuristic is performed to quickly schedule high-probability ISLs according to a prediction model,which is trained from the high-quality MA solutions.The main idea of the DHMA is to address normal and quick-response schedulings separately,while high-quality normal scheduling data are trained for quick-response use.In addition,this paper also presents an easy-to-understand ISL scheduling model and its NP-completeness.A seven-day experimental study with 10080 one-minute ISL scheduling instances shows the efficient performance of the DHMA in addressing the ISL scheduling in normal(in 84 hours)and quick-response(in 0.62 hour)situations,which can well meet the dual scheduling requirements in real-world BDS applications.

BDS-3 PPP-B2b实时精密时间同步方法探讨

针对传统实时精密单点定位(PPP)时间同步方法需要连接互联网,以及对北斗三号全球卫星导航系统(BDS-3)精密单点定位服务信号(PPP-B2b)用于长基线实时时间同步的研究较少的问题,提出一种将PPP-B2b信号用于PPP时间同步的实时时间同步方法:将高精度铷原子钟作为全球卫星导航系统(GNSS)接收机外频标输入,通过GNSS接收机实时接收PPP-B2b改正数,解算接收机钟差并实时调整铷原子钟,输出与时间基准同步的秒脉冲(1PPS)信号,较之传统GNSS接收机输出1PPS有更佳的频率稳定性;设计PPP-B2b时间同步硬件测试平台对提出的PPP-B2b时间同步方法进行测试。结果表明,通过PPP-B2b时间同步方法进行时间传递的精度优于0.2 ns;短基线实测实时时间同步精度优于0.95 ns;卫星模拟器仿短基线精度优于0.87 ns,仿长基线精度优于0.9 ns。

岸基BDS-R海面测高及其观测值加权方法

随着北斗三号卫星导航系统(BDS-3)的全球组网完成,其反射信号在全球导航卫星系统反射测量(GNSS-R)海面测高领域的应用也更加广泛。为研究BDS-3 B1C反射信号码延迟海面测高性能,以及多星测高数据组合方法,进行了基于B1C码信号的双天线岸基北斗卫星导航系统反射测量(BDS-R)码延迟海面测高实验。利用自主研发的GNSS-R测高软件接收机对实验数据进行事后处理,将测高结果与岸基同步观测的雷达测高仪所测海面高度值进行对比分析,并基于反射信号信噪比(SNR)和卫星高度角加权的方法对多星测高观测值进行加权计算,评定BDS-R海面测高精度。结果表明:自主研发的GNSS-R测高软件接收机可用于海面测高,基于B1C码信号的BDS-R海面测高精度有达到分米级的可能性;根据10 s观测数据平滑可以得到,单颗卫星B1C码信号最优测高结果的均方根误差(RMSE)为0.634 m,平均绝对误差(MAE)为0.507 m,多星测高观测值加权组合最优结果的均方根误差为0.538 m,平均绝对误差为0.500 m,明显优于单星观测精度,最大可提升70%,最小可提升17%;针对同一信号多星GNSS-R测高数据加权方法,应用综合考虑卫星高度角和反射信号信噪比的加权模型优于其他加权模型,测高精度分别比信噪比分段模型、正弦函数模型、指数函数模型、等权模型提升9.4%、9.5%、20.5%、35.2%。

GPS/Galileo/BDS-3广播星历精度分析

为了分析当前GPS(Global Positioning System)、Galileo(Galileo Navigation Satellite System)和BDS-3(Beidou Navigation Satellite System with Global Coverage)广播星历的精度,详细分析研究了各种偏差改正及消除方法,并尽可能地消除了系统误差和粗差对评估结果的影响。选取2021-11-01/12-31共61天MGEX(multi-GNSS experiment)发布的多系统混合广播星历与武汉大学分析中心发布的事后精密星历数据进行实验,对GPS、Galileo和BDS-3近期广播星历精度进行对比分析,实验结果表明:3个系统广播星历整体精度由高到低依次是Galileo、BDS-3和GPS,其空间信号测距误差的RMS(root mean square)分别优于0.17、0.25和0.37 m,整体轨道精度的RMS分别优于0.17、0.12和0.25 m,BDS-3广播星历的轨道精度最高,钟差误差的RMS分别优于0.15、0.23和0.27 m,Galileo广播星历的钟差精度最高。对于GPS卫星的广播星历,blockⅢA卫星钟差和轨道精度均优于其他GPS类型卫星。

Design of Space-based PNT System Based on BeiDou Navigation Satellite System

BeiDou navigation satellite system(the BeiDou system) is the only PNT(Positioning, Navigation and Tim-ing) resource in China that has coverage of the globe and near-Earth space and provides continuous high-precision,low-cost positioning, navigation and timing solutions for users in a unified spatio-temporal benchmark. As an importantspatio-temporal benchmark transmission system, the BeiDou system is the most important resource for the nationalPNT system to provide a PNT capability under a unified spatial-temporal benchmark. This paper proposes the con-cept, composition and development model of the space-based PNT system design based on the BeiDou system withall its space characteristics, as well as the advantages of the system. It opens up a new direction for the construction ofChina's PNT system and expands a new horizon in the research of a PNT system in China.

BDS-3单频三种差分定位方法的性能初步评估

为进一步分析北斗三号全球卫星导航系统(BDS-3)B3I、B1C、B2a和B1I单频差分定位精度,利用全球14个MGEX测站构成基线长度在30km以下的7条基线2022-09-01到2022-09-30共30d观测数据,在评估可视卫星数和信噪比基础上,初步评估了BDS-3B3I、B1C、B2a和B1I单频伪距差分、载波平滑伪距差分和载波相位差分定位精度。结果表明:数据质量方面,BDS-3B3I、B1C、B2a和B1I可见卫星数和信噪比基本符合解算需求;差分性能方面,B1C和B2a相当,B3I和B1I略差;伪距差分E、N、U方向优于0.6m,点位精度优于0.8m,单频平滑效果B1C优于B3I、B1I和B2a,在E、N、U方向分别平均提升21.34%、22.2%和17.17%。设置平滑值和原始伪距阈值定位精度得到较好的提升;BDS-3载波相位差分B3I定位精度优于7 cm,B1C定位精度优于5 cm,B2a定位精度优于6 cm,B1I定位精度优于5cm。总体定位精度随着基线长度逐渐下降,单频伪距差分定位精度达到分米级,载波平滑伪距中短基线定位精度相较于伪距差分能够提升40%,长基线提升20%,载波相位差分为用户提供厘米级定位精度。

基于BDS的建筑物沉降监测与分析

将北斗卫星导航系统(BDS)应用于变形体变形监测中,以评估BDS在施工干扰下的变形监测性能具有重要示范意义。本文通过BDS采集建筑物在施工期及工后期的变形数据,针对监测数据呈现的波动性与随机性特征,首先,使用改进小波阈值函数方法进行降噪处理;其次,对比BDS降噪处理后的数据与水准监测数据;最后,预测建筑物最终沉降量。实测BDS建筑物监测数据并进行处理,结果表明,施工期受多种因素干扰,BDS监测数据中包含大量噪声,本文提出的改进小波阈值函数降噪法能够有效剔除BDS监测数据中的噪声,降噪后数据与水准数据平均相对误差低于10.9%;采用抛物线模型对降噪后数据进行预测,得到当沉降稳定时的最终沉降量范围为-53.43 mm~55.26 mm。本文通过对BDS监测数据进行处理,实现对建筑物沉降变形的有效预测,验证了BDS在施工干扰环境下仍然具备良好的性能。

BeiDou Regional Navigation Satellite System Completed

As the 16th BeiDou navigation satellite was successfully launched into space at 23:33 Beijing Time from the Xichang Satellite Launch Center (XSLC) on October 25, 2012, China completed the construction of the BeiDou Regional Navigation Satellite System that starts to officially provide services for most parts of the Asia-Pacific region from December 27. The 16th BeiDou navigation satellite, the last one for the regional BeiDou system, was developed by China Academy of Space Technology under CASC.

适用于高高原机场GPS/BDS导航快速选星算法分析

卫星导航系统是民航飞机导航的主要手段之一。因高高原机场环境复杂多变,单一GPS导航系统难以满足现实需求。基于GPS/BDS双模导航能显著提高导航性能,具有明显优势。但这将带来大的卫星冗余,增加了计算量的同时会引入更多低导航质量的卫星。为此,针对高高原机场情况,提出一种基于卫星仰角和方位角的快速选星算法,可以减少计算负担,同时自动选出高质量卫星信号,满足实际的导航需求。最后,选取4个典型的高高原机场场景对算法进行了充分的仿真实验分析。仿真结果验证了所提方法的有效性。

Construction of BDS Spatiotemporal Information Agricultural Product Digital Credit System

Spatiotemporal information,positioning and navigation services have become important elements of new type infrastructure.The rapid development of global digital trade provides a large-scale application scenario for the use of Beidou Navigation Satellite System(BDS)spatiotemporal information to support the certification of origin of agricultural products.The BDS spatiotemporal information agricultural product digital credit system uses such modules as BDS,spatiotemporal information collection,spatiotemporal coding,and spatiotemporal blockchain.It incorporates multi-level joint supervision mechanisms such as government,associations,and users.Starting from the initial production link of agricultural products,it realizes the correspondence and locking of online and offline products,effectively improves the integrity and credibility of information in the production process,finished product quality and circulation process of products,effectively manages the green production and anti-channel conflicts of producers,and provides credible information for consumers,thus realizing the digital credit certification of products.The successful practice of characteristic agricultural products in Yunnan Province has verified the application ability of the BDS spatiotemporal information agricultural product digital credit system.This system has played a significant role in promoting the online and offline locking,credible information,effective supervision and high quality and high price of characteristic agricultural products from the field.The BDS provides services for global digital trade and contributes to the further enhancement of the global application scale of GNSS.

China Launches the 11th BeiDou Satellite in Navigation Satellite System

China launched the 11th BeiDou navigation satellite in their BeiDou Navigation Satellite System.The satellite was launched from the Xichang Satellite Launch Center in Sichuan Province on a LM-3C rocket at 0:12 on February 25 (Beijing time) and was put into the predetermined transfer orbit successfully.The geostationary satellite is the first BeiDou navigation satellite launched in 2012 for the

The 10th BeiDou 2 Navigation Satellite Flew into Space

LM launch vehicles established a new record by successfully performing the 16th successful flight this year.A LM-3A launched the 10th BeiDou 2 satellite into its predetermined transfer orbit on December 2 from the XSLC in Sichuan Province.

Networking of BeiDou Navigation Satellite System Accelerated with Two New Members

At 4:50 on April 30, China's LM-3B/I rocket, an improved type based on LM-3B, made its debut at the Xichang Satellite Launch Center and successfully sending the 12th and 13th BeiDou Navigation Satellite System satellites into the planned transfer orbit in space. It was the first time that China launched two BeiDou satellites with one rocket. It was

基于长基线的BDS精密星历精度对比分析

为对比分析欧洲定轨中心(CODE)、德国地学研究中心(GFZ)与武汉大学(WHU)3种北斗卫星导航系统(BDS)精密星历精度及BDS地球静止轨道(GEO)卫星精度影响,本文选取亚洲和欧洲区域多模全球导航定位系统(GNSS)实验跟踪网(MGEX)测站,从基线结果可靠性、内符合精度、外符合精度3个方面对比分析。结果表明:3种精密星历BDS基线约束固定解NRMS值均小于0.3,说明基线结果精度可靠;BDS基线各分量固定误差均在1 cm以内,比例误差优于9×10^(-9)。亚洲区域,CODE内、外符合精度最高,以GPS基线结果为外部参考,基线平均3D误差为5.13cm;欧洲区域,三种精密星历精度一致,且BDS内符合精度优于GPS,基线平均3D误差为1.90cm左右。亚洲区域禁用BDS GEO卫星后,GFZ与WHU BDS基线水平与垂直分量内符合精度分别平均提高约26.3%、23.9%,外符合精度分别提高约39.1%、51.0%。BDS数据高精度处理时,根据区域选择精密星历并禁用GEO卫星。

复杂环境下GPS+BDS-3 PPP/INS紧组合算法性能分析

针对城市复杂环境下精密单点定位(PPP)连续高精度定位受限的问题,本文基于北斗三号全球卫星导航系统(BDS-3)与全球定位系统(GPS)双系统,利用PPP与惯性导航系统(INS)紧组合算法来改善城市复杂环境下定位性能。通过构建GPS+BDS-3双系统PPP/INS紧组合滤波模型,分别对GPS PPP、GPS+BDS-3 PPP、GPS PPP/INS紧组合、GPS+BDS-3PPP/INS紧组合4种方案在城区开阔、复杂环境下的定位、测速、定姿性能进行了分析和评估。实验结果表明,开阔环境下PPP/INS紧组合相比PPP定位精度略有提升;而在复杂环境下PPP/INS紧组合可显著解决PPP定位结果连续性和有效性较差的问题;引入BDS-3后,PPP/INS紧组合导航性能进一步提升,GPS+BDS-3 PPP/INS紧组合相比GPS PPP/INS紧组合,在东、北、天方向上,开阔环境下定位精度分别提升18.5%、32.7%、43.2%,复杂环境下定位精度分别提升35.9%、49.1%、56.5%。

GPS/BDS组合导航系统的精密单点定位模型

为了改善单卫星导航系统由于卫星数量较少,导致定位误差高的问题,设计全球定位系统(GPS)/北斗卫星导航系统(BDS)组合导航系统的精密单点定位模型:线性组合处理GPS与BDS的伪距和载波相位观测值,并构建GPS/BDS组合导航系统的组合观测值;接下来利用协方差成形自适应卡尔曼滤波方法,对组合导航系统导航过程中的卫星钟差、电离层延迟等误差实施滤波;再利用滤波处理后组合导航系统的广播星历,获取卫星轨道以及钟差;然后利用经验模型修正对流层延迟,获取相位观测值与伪距的综合改正数;最后利用综合改正数修正组合导航系统的观测方程,构建精密单点定位模型。实验结果表明,GPS/BDS组合导航系统采用所构建模型进行精密单点定位,不同方向定位误差均低于10 cm,证明了提出模型的有效性。

BDS-3/Galileo四频精密单点定位模型及性能分析

北斗三号系统(BDS-3)与欧盟伽利略系统(Galileo)都能提供四频及以上的卫星信号。为充分利用多频信号数据,提高定位精度和可靠性,建立了BDS-3/Galileo四频精密单点定位模型并进行了性能分析。首先在传统双频模型基础上推导了两个四频无电离层组合模型(QF1和QF2)和一个四频非差非组合模型(QF3),并给出了各模型组合系数、电离层和噪声放大系数等参数。其次分析了各模型参数对定位性能的影响。最后通过静态和仿动态PPP实验评估了各模型的定位性能,实验结果表明:提出的四频模型QF1、QF2、QF3静态PPP收敛时间相较于双频模型IF12缩短了约50%、57%、25%,收敛后定位精度分别提升约44%、44%、41%;动态PPP实验中,QF1、QF2、QF3模型所用收敛时间较IF12模型分别缩短约26%、26%、3%,收敛后定位精度分别提升约23%、22%、13%。QF1和QF2模型性能相当,优于QF3模型。