基于CS-BP的列车卫星定位欺骗干扰检测方法

Spoofing interference detection method for satellite-based train positioning based on CS-BP

随着列车运行控制模式车载自主化、系统智能化发展需求的不断深化,新型列车运行控制系统的设计与运用对列车测速定位自主性、可信性的需求愈发显著。全球导航卫星系统因其具备覆盖范围广、定位精度高、全天候等优势,成为新型列车控制系统实施列车自主定位的重要发展应用方向。卫星导航系统存在显著脆弱性,来自铁路沿线运行环境的干扰会对列车定位感知性能形成严重威胁,因此,准确、及时检测并识别干扰的发生是实施有效防护并确保列车运行安全的关键。欺骗式干扰通过信号转发或者定制生成虚假卫星信号信息,可诱骗接收机终端使其解算出错误的定位结果,具有复杂性、隐蔽性和危害性,对特定设备的影响极大。基于此,研究并提出一种列车卫星定位欺骗干扰检测方法。首先,分析列车卫星定位面临的欺骗干扰特征;其次,提取对欺骗干扰敏感的观测量构建典型特征量;然后,设计包括样本集构建、离线模型训练、在线检测识别等环节的欺骗干扰检测总体方案,提出基于布谷鸟搜索算法改进BP神经网络的卫星定位欺骗干扰检测模型构建方法;最后,搭建列车卫星定位欺骗干扰测试环境,采用多种观测信息及特征实施干扰样本的CS-BP模型训练并将其用于识别特定形式欺骗干扰的存在与特征,结合不同类型欺骗干扰注入测试对所提出检测方法的性能进行验证与对比。研究结果表明:布谷鸟搜索策略能够扩大搜索范围,跳出局部最优并实现快速迭代收敛,且收敛寻优性能受参数条件影响较小;基于布谷鸟搜索改进BP神经网络的建模方法相对常规地图匹配残差门限检测及代表性机器学习方法具有更优建模性能,对不同种类卫星定位欺骗干扰模式的检测准确率更为稳定,在时间敏感度、精确度、F1分数等方面更具优势。研究成果对列车卫星定位及其应用的欺骗干扰检测与干扰防护具有重要支撑意义,可为新型列控系统中卫星定位感知技术的可信应用提供有效途径,能够减少设置应答器、轨道电路等轨旁设备,有效降低建设及维护成本,有效提升车载设备应对复杂定位观测环境的自主性、灵活性及安全性。

With the continuous development need of train operation control system with the higher autonomy level of the train-borne sub-system and intelligent capability,the design and implementation of the novel train operation control systems require more autonomy and credibility capabilities of train speed and localization determination.Considering the advantages of the Global Navigation Satellite System(GNSS)with the wide coverage,high positioning accuracy level and the all-weather capability,satellite-based positioning has become an important development direction for the implementation of autonomous train positioning in novel train control systems.Due to the significant vulnerability of the satellite navigation systems,the interference to GNSS from the operational environment along the railway line will pose a serious threat to the performance of train positioning and state perception.Therefore,accurate and timely detection and identification of the existence of the GNSS interference has been a key issue to realize effective protection against the interference and ensure the safe train operation.The GNSS spoofing attacker may broadcast fake satellite signal information through signal retransmission or customized signal generation,which can deceive the GNSS receiver to calculate the wrong positioning result.Thus,the spoofing interference is more complex,convert and hazardous,which has a significant impact on specific GNSS devices.In the paper,a spoofing detection method for GNSS-based train positioning was proposed.Firstly,the features of spoofing interference to satellite-based train positioning are analyzed.Secondly,the typical feature quantity was established by extracting specific GNSS observations that are sensitive to the interference attack.Then,the overall spoofing detection scheme was designed,including sample set construction,off-line model training,on-line detection and recognition.Under this framework,a GNSS spoofing detection model construction method was proposed based on the BP neural network that is improved by the Cuckoo Search(CS)algorithm.Finally,a test environment for spoof injection to satellite-based train positioning was built,and a variety of observation information and characteristics of satellite positioning were fully used to identify the existence and characteristics of specific spoofing interference.The performance of the proposed detection method was examined and compared through spoofing injection tests.The results showed that the Cuckoo search strategy can expand the search scope,jump out of the local optimal and achieve fast iterative convergence.The convergence optimization performance by CS is less affected by the parameter conditions.The CS-enhanced BP neural network modeling solution can achieve the higher modeling performance than the conventional map matching residual threshold-based strategy and representative Machine Learning(ML)based methods.The detection accuracy of the proposed solution under different spoofing attacks is more stable,with better performance in time sensitivity,accuracy and F1 score.The proposed solution is capable of providing great support to the spoofing detection and interference protection in satellite-based train positioning and the locationenabled applications.It can provide an effective way to reliably utilize the satellite-based positioning and perception technology in novel railway train control systems.It can make it possible of reducing the trackside equipment like balises and track circuits,effectively reducing the cost of construction and maintenance,and improving the autonomy,flexibility and safety of the train-borne sub-system under complicated train positioning observation environments.