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针对多播业务中,无线网络如何在带宽和时延受限的情况下,实现对于多个处于空闲状态的移动用户的跟踪定位问题,提出了一种有效的基于二分图匹配模型的多播寻呼机制.其主要思想是首先通过利用信息论中熵的概念对移动用户的位置不确定性进行分析,为了减少位置更新开销,采用LZ78压缩算法实现位置更新和位置概率预测.然后多播寻呼系统为减少寻呼开销和时延,在每个寻呼周期内为所有移动用户分配的寻呼小区驻留概率之和最大,且满足带宽限制和用户公平性.针对该目标,基于二分图匹配的多播寻呼算法BMPS构建二分图模型,将位置概率转化为权值,通过动态修改权值,获取二分图最大权完美匹配,实现用户与寻呼小区之间的最优分配方案.仿真实验结果表明,基于二分图匹配的多播寻呼算法能够有效实现寻呼开销和时延的总体性能优化,且减少了用户冲突对寻呼性能影响. 相似文献
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长期演进(long term evolution,LTE)系统中,接纳控制是保证用户服务质量(quality of service,QoS)要求的重要技术之一。针对现有资源预留算法受预留门限值影响较大,且掉线率较高的缺点,提出一种适用于LTE系统的基于排队机制的动态资源预留算法。首先该算法通过设置门限预留部分资源,让切换呼叫直接接入,新呼叫以新定义的请求概率动态接入。其次在系统资源耗尽时,对切换呼叫采取排队机制,等待系统有剩余资源时接入。仿真结果表明,所提算法能有效降低切换呼叫掉线率,提高资源利用率,并且算法受预留门限值的影响较小。 相似文献
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多层卫星网络结构复杂,信道资源有限。对多层卫星网络信道资源进行高效管理,能够提高卫星系统整体效率。为此,提出了一种面向多层卫星网络的信道资源管理方法。针对LEO/MEO/GEO三层卫星网络,首先根〖JP2〗据业务类型划分优先级,其次运用自回归积分滑动平均(autoregressive integrated moving average,ARIMA)〖JP〗模型预测小区内新呼叫业务用户量,然后根据预测用户量和卫星剩余信道带宽为用户选择接入层,再利用博弈模型判断是否允许用户接入,最后根据降级因子选择降级用户让出信道带宽。仿真结果表明,该方法能够降低整体阻塞率,提高整体效用。 相似文献
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异构无线分组网络中的接入选择机制 总被引:1,自引:0,他引:1
传统多接入选择(Multi-Radio Access Selection)方法只针对话音业务,在设计中仅仅考虑已接入用户数及系统容量,由于未将"分组级"信息考虑在内而不适用于无线分组网络。提出了一种新的异构无线分组网络中的接入选择算法,分组业务在多接入选择时考虑了实时、非实时的不同QoS要求和链路自适应机制(链路层重传及自适应调制编码);用户接入后,在保证其QoS的基础上,同时达到不同网络间负载均衡的目的。基于OPNET Modeler的动态仿真对算法性能进行了仿真评估,并与传统的最小用户数和最小路径损耗多接入选择方法在保证业务QoS和负载均衡性能方面进行了比较。 相似文献
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为实现空中信息分发平台对战场多任务网络带宽资源的有效管理,在战术互联网资源管理模型中,提出一种等级优先动态带宽分配(classification prioritized dynamic bandwidth allocation,CPDBA)算法。该算法改进了基于网络效能最大化的带宽分配方法,优化了对指数效能业务的调度策略。仿真结果表明,该算法不但能够使相同带宽资源产生更高的任务价值,而且在网络过载时可以确保高优先级业务的服务质量,从而有效解决了多任务网络的链路带宽竞争问题。 相似文献
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针对采用自适应智能天线的分布式无线系统,从理论上分析了上行链路的负载因子,建立了基于该系统的干扰预测理论模型,并提出了两种基于干扰预测的上行链路接入控制算法.利用建立的干扰预测模型,可获得新用户给系统带来干扰的预测,从而可提高接入控制算法性能.仿真结果表明,基于干扰预测的接入控制算法在采用优化的接入控制门限时能够有效提高系统性能.当接入控制算法根据干扰的分布为用户灵活选择接入天线时,能够降低系统阻塞概率,但是却以牺牲系统中断性能为代价. 相似文献
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Amy J. C. Trappey Charles V. Trappey Sandy W. C. Chang W. T. Lee Tun Nien Hsu 《系统科学与系统工程学报(英文版)》2016,25(2):229-253
A global enterprise must continuously improve the efficiency of logistic operations between supply chain collaborators. Integrating logistic services, resources, and necessary information flows in the supply chain to ensure efficiency and efficacy is critically important to these companies. Global logistic service companies face challenges from their clients to provide logistic services that are cost effective, accurate, and seamlessly integrate material, information and cash flows. In this research, an improved framework for one-stop logistic services is systematically designed, analyzed, and evaluated. The one-stop logistic service framework, defined in four models, is developed to provide enterprises with integrated and comprehensive services within the global supply chain context. The levels of service importance are assessed using a four categories questionnaire. This research provides a case study of the implementation of one-stop logistic services in the distribution industry and demonstrates the framework operating under different demand conditions. Finally, system dynamics causal evaluation is used to evaluate the advantages of the logistic service framework. 相似文献
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GPS/GLONASS组合导航定位技术在ITS中的应用 总被引:4,自引:0,他引:4
采用先进的组合导航技术 ,将现存的两种 GPS( Global Positioning System )和 GLONASS( Global Navigation Satellite System)全球卫星导航系统结合一起 ,可以充分发挥 GPS和 GLONASS各自优势 ,并可优劣互补 .GPS/GLONASS组合定位导航 ,利用先进的组合技术 ,充分利用 GLONASS无 SA影响的特点 ,提供可靠性高、完善性好的高精度定位服务 ,使得整个系统可视卫星的数目增加多 ,可在任何地方有较大高度角的卫星提供选择 ,从而改善了卫星几何位置配置 ,提高了系统的可靠性 .将 GPS/GLONASS组合定位导航技术应用于 ITS中的车辆定位导航 ,可以提供全方位、全天候、多星定位车辆导航的服务功能 ,为实现道路交通管理“自动化”、车辆行驶“智能化”提供可靠的技术保证 ,具有良好的应用价值和实用价值 . 相似文献
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基于主体的语义Web服务的Petri网模拟方法 总被引:2,自引:0,他引:2
语义web上的服务在执行时可以将其视为一个智能主体的行为执行的过程,并且能够通过智能主体管理语义web上的服务。将语义web上存在的主体分为用户主体,媒介主体和服务主体三类。当一个用户主体需要多个不同的web服务来完成其目标时,这些服务将被组装为一个组合服务。对组合服务的动态执行进行准确的模拟和全面的分析是保证用户目标实现的关键问题,利用Petri网的方法对组合语义web服务进行模拟和动态执行分析是关于此问题的一种实用并且有效的方法。 相似文献
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军用通信网正在向数字化、综合化和智能化方向发展,设计和开发能够提供多种业务接入的军用综合接入设备是保障部队通信高效运行的一项迫切需求.阐述了发展军用综合接入设备的背景和必要性,并提出了通过发展能实现业务综合的接入设备的ISDN过渡的策略.重点对我们正在业务能务和应用场合,最后对军用综合接入设备的应用前景进行了展望. 相似文献
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On integration and adaptation in complex service systems 总被引:6,自引:6,他引:0
James M. Tien 《系统科学与系统工程学报(英文版)》2008,17(4):385-415
The services sector employs a large and growing proportion of workers in the industrialized nations, and it is increasingly dependent on information and communication technologies. While the interdependences, similarities and complementarities of manufacturing and services are significant, there are considerable differences between goods and services, including the shift in focus from mass production to mass customization (whereby a service is produced and delivered in response to a customer's stated or imputed needs). In general, services can be considered to be knowledge-intensive agents or components which work together as providers and consumers to create or co-produce value. Like manufacturing systems, an efficient service system must be an integrated system of systems, leading to greater connectivity and interdependence. Integration must occur over the physical, temporal, organizational and functional dimensions, and must include methods concerned with the component, the management, and the system. Moreover, an effective service system must also be an adaptable system, leading to greater value and responsiveness. Adaptation must occur over the dimensions of monitoring, feedback, cybernetics and learning, and must include methods concerned with space, time, and system. In sum, service systems are indeed complex, especially due to the uncertainties associated with the human-centered aspects of such systems. Moreover, the system complexities can only be dealt with methods that enhance system integration and adaptation. The paper concludes with several insights, including a plea to shift the current misplaced focus on developing a science or discipline for services to further developing a systems engineering approach to services, an approach based on the integration and adaptation of a host of sciences or disciplines (e.g., physics, mathematics, statistics, psychology, sociology, etc.). In fact, what is required is a services-related transdisciplinary - beyond a single disciplinary - ontology or taxon 相似文献
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基于QoS资源控制是保证网络综合应用服务质量的必要手段。深入讨论了基于QoS最优综合服务通信系统(ISCS)模型及其最优资源控制策略和评价方法。建立了ISCS最优动态资源控制系统模型。针对资源控制重要部件buffer,又提出了面向buffer资源控制策略,并取得了良好的模拟结果。 相似文献
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通过面向服务的架构(SOA),来搭建采购与物流一体化的服务系统,降低系统的成本.为了弥补SOA在服务质量分析方面的不足,将价值模型引入SOA的服务体系中,从功能性和非功能性两方面对顾客需求进行形式化描述;采用扩展的UML时序图对服务流程进行描述;使用Pi演算及价值状态图验证目标价值的可实现性;通过价值实现程度计算函数定量计算采购物流系统对顾客需求的满足情况.最后对一个采购物流系统实例的仿真数据进行分析验证,仿真结果表明,将价值模型引入SOA服务体系可以有效弥补SOA对采购物流服务组合的服务质量分析方面的不足,并对以后的服务组合优化提供指导. 相似文献
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A CASE FOR SERVICE SYSTEMS ENGINEERING 总被引:10,自引:6,他引:10
A case is made for further developing a branch of systems engineering that focuses on problemsand issues which arise in the service sector We promulgate this special focus not only because of thesize and importance of the service sector but also because of the unique opportunities that systemsengineering can exploit in the design and joint production and delivery of services. We begin byconsidering the economic, technological and demographic contexts within which the service sector hasflourished; we then address both services, especially emerging services, and systems engineering,followed by a discussion of how to advance the field of service systems engineering, and concludingwith several remarks. In particular, a number of service systems engineering methods are identified toenhance the design and production/delivery of services, especially taking advantage of the uniquefeatures that characterize services-namely, services, especially emerging services, are information-driven, customer-centric, e-orien 相似文献