【作者】 李健；

【导师】 许其凤；

【作者基本信息】 解放军信息工程大学 ， 测绘科学与技术， 2011， 博士

【摘要】 国内外的CORS应用领域呈现出“建设规模化”和“服务实时化”的发展态势,即在已有的行业型、区域型等多个独立型CORS系统(iCORS)的基础上,将各个覆盖区域相邻的iCORS进行互联,形成拥有相当数量基准站的、更高层次的联合型连续运行基准站网(cCORS),在静态定位服务技术较为成熟完善的基础上,提供大范围、高动态、高精度的实时定位服务。要打破目前iCORS区域分割、独立运行的局面,实现向跨地区、跨行业、跨机构的cCORS的顺利过渡,除了统筹兼顾各方面需求,制定合理的规范标准体系,有目标地增加点位分布密度之外,还需要利用新的理念和技术手段,建立新的数据处理与服务模式,推动各类iCORS互联、互通和互操作。通过对网格技术在地学领域(尤其是大地测量领域)的应用研究发现,网格技术可以有效解决CORS领域中的系统异构、系统互操作和资源服务管理等瓶颈问题。本文基于Web服务(WS)和网格服务(GS)技术,对面向cCORS的动态定位服务机制开展了相关研究,概况起来,主要包括:(1)定位用户需求模型。对cCORS用户群落从服务类型、服务内容、定位技术等作了详细分析,对各类定位技术的应用领域、精度要求、时间可用性和有效性等作了汇总,得到了cCORS的服务谱系和详细需求。分析了定位用户需求多样化对系统异构的影响,提出了“需求包容、逻辑重组”的解决思路。提出并定义了一种以域、类型、属性、值和条目为主体的树状结构用户需求模型,给出了较为精细合理的语义描述方法。建立了用户需求模型的映射机制,详细定义了用户需求模型、服务情景和业务流程之间的映射关系。提出了用户角色模型,进一步明确了CORS用户群与定位服务情景之间的对应关系。(2)cCORS体系结构。从协议规范、层次结构、物理结构和逻辑结构等4个视角,建立了以专业计算与综合服务为中心的网格体系结构。建立了由互联网协议簇、XML协议簇、网格协议簇、GNSS协议簇和GNSS应用协议等组成的面向协议的层次结构。建立了由基础层、通讯层、服务层、业务层和应用层组成的面向服务的层次结构。给出了一种“物理分散、逻辑集中”的松耦合分布式体系结构,可以融合现有的iCORS并保证其自治性,并可将计算任务分散到多个处理节点中,解决了资源利用的最大化和服务的最大限度提供问题。研究提出了面向服务的逻辑结构,一种是事后在线服务体系,另一种是实时动态服务体系,分别给出了直观具体的逻辑流程。在综合考虑内聚性与耦合性的基础上,构建了cCORS元服务和高级应用服务体系,并给出了构建原则、分层结构、职能列表和部署方法。(3)网格计算理论模型。提出了一种新的面向cCORS的网格计算理论模型——附有扩展指令集、语义集的并行多带主动存储计算模型(PM-CAM),用来研究网格计算的协议与机制、网格程序的算法设计与复杂度评估、网格服务的通信与资源调度、网格服务质量评估等问题。给出了PM-CAM模型与网格架构之间的映射关系,通过对用户动态定位服务的指令流案例分析,证明了该模型可用于实时动态定位相关计算的复杂性描述与性能表达,可为后续的软件设计和部署提供有效的理论指导。(4)数据特征分析。针对CORS数据多样性和数据异构问题,提出了对数据进行结构化和虚拟化的解决思路。分析了广义GNSS的多频多模数据源的增加对cCORS数据采集、数据处理、定位服务等一系列流程产生的影响。阐述了由CORS站形成的传感器网络的分布性、并行性、覆盖性、连通性和容错性等诸多特性要求。分析了与CORS定位业务密切相关的数据采集、存储和远程数据传输等多种协议标准。针对各个成员iCORS建设标准和测绘基准不统一、数据格式制式和采样率存在差异等问题,基于缓冲池和线程池技术,建立了数据实时聚集与融合机制,并给出了数据传输质量指标评估方法。(5)数据采集与分发机制。对原始观测数据和动态差分数据的传输量进行了计算分析,研究了并行传输、容错传输、并行容错传输、分布传输和汇集传输等多种实时数据采集与分发机制。针对非确定性网络连接环境和复杂多向数据流等状况,设计了CORS数据流服务协议(CSDS),针对4种应用场景完成了对数据传输服务的封装与部署,可以较好地适应cCORS较为繁杂的数据通讯链路。建立了面向广义GNSS多模多频观测数据的分布式采集、融合和分发体系,使得任意基准站采集的数据能被多个计算节点同时访问,形成了跨区域的多节点并行互联模式。面向多种互联方式形成的复杂网络拓扑结构,如中心互联、中心集成、站共用和站中继等,在应用层面提出了数据传输优化方案。建立了跨逻辑域传输的分层覆盖机制,并提出了相应的传输优化服务方法。为了增强数据传输链路的可靠性,提出了一种改进的前向式算法(MPA),在转发树中预留链路专用于树重构,并对备用链路建立后的树重构策略进行了分析。(6)系统异构问题与虚拟化技术。从系统异构、信息异构和服务模式异构等角度,详细分析了cCORS的异构问题,并对资源的动态性、自治性和二分性作了探讨,指出了上述资源特性给资源管理带来的挑战。按可复用特性、可复制特性、可移动特性和管理逻辑特性等4个方面对cCORS中各类资源进行了分类,指出随着CORS技术的发展和服务领域的拓宽,资源种类和功能更加多元化,使得资源协同变得愈加困难。针对上述挑战,提出了“资源虚拟化”和“服务标准化”的解决思路,即采用虚拟化技术实现资源(Resource)与服务(Service)的融合,基于现有WS和GS的各种协议规范实现服务的标准化,为所有部署在资源上服务提供通用界面,进而实现资源管理和服务协同,为构建基于网络的复杂GNSS业务应用提供支持。对WS和GS的技术体系及其发展状况作了详细分析,采用WSRF来实现cCORS资源与服务的一体化管理,并将WS-BPEL作为cCORS服务组合和工作流的编制语言。(7)资源管理与服务机制。提出了2种资源管理方法,建立了cCORS的资源管理模式,设计了由代理器、注册器、管理器和资源库等4部分组成的资源注册中心。提出了2个层次的服务组合方法,分别用于WS/WS-R组织维护和WS-BPEL业务流程编制。按照资源层、服务层、组合层和需求层等4个层次,设计了cCORS服务体系的逻辑结构。在服务资源匹配方面,面向单个服务遴选提出了映射服务集的概念,面向多个服务组合优选提出了组合适配器的概念,提高了匹配的自适应性。(8)基于虚拟基准站网(vCORS)的动态定位服务技术。提出了vCORS的概念,从应用层、服务层和设施层等3个概念层次阐述了vCORS的运作逻辑。从元服务体系的建立、生命周期管理、网型构造与优化、自动更新与切换机制和服务质量指标体系等多个环节,分析了基于vCORS的实时动态定位服务流程。建立了vCORS自动变更机制,提出并定义了一种服务策略描述语言(SEPL),对8类较典型的变更事件作了分析。利用SEPL对变更事件的发生、捕捉与处理机制做了规范化描述,使得变更事件与服务直接对应。对vCORS实时服务质量的评估方法进行了探讨,建立了面向用户的可量度性业务类QoS指标体系。在对事后在线精密定位服务分析的基础上,提出了实时在线精密定位服务的概念和实现思路。(9)软件原型。自主开发了面向cCORS的动态定位服务的软件原型,并在模拟环境下面向实时动态定位服务,分用户需求响应、数据传输、服务部署、vCORS生成与销毁、服务制品分发和用户定位质量等6个方面,对软件原型的关键环节和算法进行了验证和测试,对各部分计算服务的正确性和合理性进行了测试,并以图表和文字等方式给出了各项测试的结果和结论,验证了原型系统的功能可靠性和工程实用性。更多还原

【Abstract】 The CORS application field shows the development trend of―extensive construction‖and―real-time service‖in domestic and overseas. Based on the existing specialty-oriented, region-oriented Independent CORS (iCORS), by interconnecting adjacent iCORS, a higher level and larger scale of Combined CORS (cCORS) can be formed which has a considerable number of base stations. It offers not only basis static positioning services, but also a wide range, high dynamic, high precision and real-time kinematic positioning services. To break the current situation of region segmentation, independently-operating of the iCORS and achieve a smooth transition to the trans-regional, cross-trade, inter-agency cCORS, we need to use new ideas and technology to establish a new data processing and service supply models, and promote all kinds of interconnection, interchange, and interoperability of iCORS, in addition to integrate all aspects of needs, develop appropriate standards system, increase the density of stations. Through research on grid computing applications of earth science (especially geodesy), it is found that the grid computing technology can effectively solve the bottlenecks of CORS, such as heterogeneous, interoperability, resource management, service virtualization, etc. In this paper, based on the technology of Web Services (WS) and the Grid Services (GS), the mechanism of kinematic positioning services for cCORS is researched, mainly including:(1) Model of positioning user demand. The service type, service content and positioning technology of cCORS user community are analyzed in detail. The applications, accuracy requirements, time availability and validity of various types of positioning technology are summed. Finally, cCORS service pedigree and user detailed requirement are obtained. By Analysis of the impact of the user demand diversity on the system heterogeneous, the paper put forward the―demand inclusiveness, logic restructuring‖solution. It proposes and defines a tree structure user demand model, with content of domain, type, attributes, values, entries. It gives a reasonable semantic description. It establishes the mapping mechanism of user demand model. The mapping relationships among the domain, type, service scene and business processes are detailed defined. A user role model is proposed, and the correspondence between user groups and positioning service scenarios is further clarified.(2) The cCORS architecture. From four perspectives of the protocol specification, hierarchical structure, physical structure and logical structure, the cCORS system structure is established based on WS and GS, with the center of professional computing and comprehensive service. The protocol-oriented hierarchical structure is established, composed by the Internet protocol suite, XML protocol suite, Grid protocol suite, GNSS protocol suite and GNSS application interface standards. The service -oriented hierarchical structure is established, composed by the foundation layer, communication layer, service layer, business layer and application layer. A "physical scattered, logical focused" loosely coupled distributed architecture is given, which can integrate existing iCORS and ensure their autonomy, and handle computing tasks across multiple processing nodes. Two types of service-oriented logical structure are proposed, one is post-positioning online service system, the other is kinematic positioning online service system. Their specific logic and process workflow are also given respectively. Considering the cohesion and coupling of algorithms, the system structure of meta-services and advanced application services is built, and the building principles, hierarchical structure, functions list, and deployment method are given.(3) Theoretical model of Grid computing. A theoretical model, named Parallel Multi-type Computer with Active Memory (PM-CAM), is proposed, with extended instruction set and semantic set. PM-CAM is used to study some problems, such as Grid protocol and mechanism, Grid program’s algorithm design and complexity evaluation, Grid service communications and resource scheduling, Grid service quality evaluation, etc. The mapping relationship between the model and the grid framework is elaborated. By analyzing the instruction stream instances of user kinematic positioning services, the feasibility of the model applied to the complex description and performance expression of cCORS is proved. Thus, the model provides effective theoretical guidance for following software design and deployment.(4) Data characteristics analysis. Aiming at the problems of data’s diversity and heterogeneous, the solution of data structuring and virtualization is put forward. The impact on the cCORS data acquisition, data processing, positioning services and a series of processes is analyzed, caused by increasing of the general GNSS multi-mode multi-frequency data sources. The requirement properties of the distributed sensor networks formed by CORS stations, such as parallelization, distribution, coverage, connectivity, fault tolerance, and many other features, is explained. Several protocol standards closely related to the CORS positioning services, being used in data collection, storage, remote transmission and other occasions, is analyzed. In view of the problems between each iCORS, such as different standard of construction, disunity of geodesy datum, different data format and observation interval and other issues, the mechanism of data real-time aggregation and integration is built, and gives evaluate method to access the data transmission quality indicators, based on the buffer pool and thread pool technology.(5) The mechanism of data collection and distribution. The transmission quantity of original observation data and kinematic difference service data is calculated and analyzed. The real-time data collection and distribution mechanism, such as parallel transmission, fault-tolerant transmission, parallel fault-tolerant transmission, distribution transmission, congregate transmission and others, is studied. Aiming at the non-deterministic network connections environment and the complex multi-stream data flow and other conditions, the CORS Streaming Data Service (CSDS) protocol is designed, as well as the data transmission services’encapsulation and deployment for four application scenes, which proves that CSDS can better adapt to cCORS complicated data communication link. The acquisition, integration and distribution system for the generalized GNSS multi-mode multi-frequency observation data is established, enabling that any data collected by stations can be simultaneously accessed by multiple computing nodes, forming a cross-regional multi-node parallel interconnection mode. Facing the complex network topologies formed by a variety of interconnecting ways, such as the central interconnecting, central integrating, stations sharing and stations relaying, etc., data transfer optimization scheme is put forward in the application level. After establishing the layered covering mechanism for cross-domain transmission, the corresponding optimization service method is proved. In order to enhance the reliability of data transmission link, the Modified Proactive Approach Algorithm (MPA) is proposed, which can be used in tree reconstruction for the backup link and the establishment strategy of tree reconstruction is analyzed.(6) System heterogeneity and virtualization technologies. In view of systems heterogeneous, information heterogeneous and service model heterogeneous, a detailed analysis of cCORS heterogeneous problems is given. Then, the dynamic, autonomy and dichotomy properties are studied, and resource management challenge is pointed out. According to reusable features, replicable features, mobile features and management logic features, the resources in the cCORS are classified. The development of the technology is pointed out, with expanding service sector, the diversion of resource’s types and functions make resource synergy more and more difficult. In response to these challenges, a―resources virtualization‖and―services standardization‖solution is proposed, that is, using integration of resources and services by virtualization technology, based on the existing WS and GS protocol specification, to realize services standardization and provide on a common interface for all service deployed in resources, thus achieving resource management and service cooperation, and supporting complex web-based GNSS applications. On analyzing technology development condition of WS and GS, WSRF is used to achieve cCORS integrated management of resources and services, and WS-BPEL is used as orchestration language of cCORS service composition and workflow. (7) Resource management and service mechanism. Two kinds of resource management method is proposed, and a cCORS resources management mode is established. A 4-part registration center is designed composing of the proxy, registrar, manager and database. A two-layer service composition method is given, that applied to the WS/WS-R organization and WS-BPEL orchestration respectively. According to resources layer, service layer, composition layer and demand layer, the cCORS services logical structure is designed. In term of the service resources matching, the concept of mapping service set is proposed for single service selection, and the concept of services combination adapter for multiple services selection, which can enhance the matching adaptability.(8) Kinematic positioning service technology based on virtual CORS (vCORS). The concept of vCORS is proposed. From the application layer, service layer and facility layer, its operation logic is described. From the establishment of meta-service system, management of life cycle, construction and optimization of network, automatic updates and switching mechanism of vCORS, QoS indicators and other aspects, the vCORS process of real-time kinematic positioning services is analyzed in detail. The automatic change mechanism of vCORS is established, the Service Event Policy Language (SEPL) is proposed and defined, and 8 kinds of typical change events is analyzed. Using SEPL, a standardized description of the change events’occurrence, capture and handling mechanisms is given, making change events directly relate to services. The evaluation method of real-time service quality of vCORS is discussed; user-oriented measurable business QoS indicators system is established. On the basis of analyzing the online high-precision post-positioning service system, the concept and realization method of the online high-precise kinematic positioning service system are put forward.(9) Software prototype. Facing cCORS real-time positioning service, a software prototype is developed independently. Under the simulation environment, for real-time kinematic positioning services, the software key prototype and algorithm are verified from six aspects, including user demand response, data transmission, service deployment, vCORS formation and destruction, service products distribution, product quality and other aspects. The correctness and rationality of some computing services are tested. The test results and conclusions are given with charts and figures, and the reliability and practicability of software prototype are verified.更多还原