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提出了一种基于虚拟实时服务的协议构架,可有效发掘用户提出通信请求之前的“负时间轴”上的空闲时频资源或可再生能源,将用户可能感兴趣的内容以多播的方式预先推送到终端的存储器中,从而以非实时的通信提供虚拟实时服务,在确保服务质量的前提下大幅度提升频谱和能量效率.对终端缓存内容的选择算法进行了标准化,从而允许基站在本地预测用户已缓存的内容,并判断当前是否应发起推送和推送哪条内容;提出了虚拟实时服务涉及的若干关键算法,也给出了虚拟实时服务的演进途径及主要开放问题,旨在为相关新兴产业的技术发展提供参考. 相似文献
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中继卫星系统用户终端关键技术分析 总被引:1,自引:0,他引:1
用户终端在跟踪与数据中继卫星系统(TDRSS)中具有重要作用.介绍了中继卫星系统用户终端的分类、功能和组成,重点对用户终端采用的全数字化可编程综合基带、自动增益控制(AGC)、相参转发和小型化等关键技术进行了总结和分析,已工程实现的用户终端功能和性能满足系统要求.最后,提出了用户终端技术的发展趋势. 相似文献
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《电子技术与软件工程》2016,(18)
云计算是一种非常强大的存储、计算服务技术,该技术可以将分布于网络各地的计算机终端、服务器、存储器集成在一起,为用户提供透明计算、分布存储、集群协作等功能,为分布式管理系统开发提供了一种新的理念,可以根据用户需求定制服务空间,分别是基础设施即服务(IaaS)、平台即服务(PaaS)和软件即服务(SaaS),实现系统并发处理功能,提升分布式管理系统的执行效率。 相似文献
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中国北斗卫星导航系统(BDS——BeiDou Navigation Satellite System),是中国自主建设、独立运行,与世界其他卫星导航系统兼容共用的全球卫星导航系统。系统建成投入运营,可在全球范围内全天候、全天时,为各类用户提供高精度、高可靠的定位、导航、授时服务。系统由空间段、地面段和用户终端三部分组成。空间段包括5颗静止轨道卫星和30颗非静止轨道卫星。地面段包括主控站、注入站和监测站等若干个地面操作控制站组成。用户终端由北斗用户终端以及与美国全球定位系统、俄罗斯格洛纳斯系统、欧洲伽利略系统等其他卫星导航系统兼容的终端组成。 相似文献
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该文针对业务上下文仅关注业务质量较少考虑用户终端环境的现状,提出终端业务上下文的概念,为普适业务的开展提供必要的信息支撑。给出一种终端业务上下文的通用定义方法,该方法可以提取各类业务场景中终端环境的特征参数,使其形成可表示、可获知的上下文。提出基于终端业务上下文的业务模型,给出上下文的存储和使用方法。最后通过一个典型的普适业务接续场景验证了上述定义方法和业务模型。结果表明,该方法可以有效提取普适业务所需的上下文信息;基于该模型,业务平台能够动态适配异构的终端环境,为用户提供个性化终端呈现和接续服务。 相似文献
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主动网络是一种新型的可计算网络体系结构,在国内外已作为下一代网络可能模型的研究热点。首先介绍主动网络及虚拟主动网络,利用虚拟主动网络,能够有效地加快网络服务的开发和部署,与此同时,用户需要灵活地管理自己提供的服务。因此,提出一种使用Script MIB对虚拟主动网络的服务进行有效的、灵活的管理模型,能够动态地实现对主动网络服务的管理。 相似文献
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针对虚拟机监视器采用软件模拟来实现I/O虚拟化所造成CPU负担重和网络I/O效率低的问题,文中基于硬件辅助I/O虚拟化的思想,提出了一种以太网控制器虚拟化模块结构设计方案。设计方案中的虚拟信息处理模块根据解析数据帧得到的信息,完成数据帧的虚拟机队列决策;分页式内存管理单元则实现数据帧内存动态管理和创建描述符队列。二者联合将数据帧分类到正确的虚拟机收发队列。实验结果表明,文中设计的以太网控制器虚拟化模块结构方案,在硬件上实现单个端口支持多个虚拟机拥有独享的数据收发通路,从而减轻CPU的负担,提高虚拟机的网络I/O效率。 相似文献
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This paper describes a novel mobile virtual-distrubuted system architecture for supporting global mobile computing and communications. the principal contribution of this paper is to innovatively apply virtual memory concepts to mobile systems by deploying mobile-floating agents to de-couple services and resources from the underlying network and allow them to move around following their mobile users. The mobile-floating agents maintain data structures associated with a mobile user. By combining the mobile-floating agent functions with a predictive mobility management algorithm and location-aware caching and prefetching, services and user data structure are pre-connected and pre-assigned at the locations to which the user is moving. Thus, the users can maintain their data structures or immediately receive service with virtually the same efficiency as at the previous location. 相似文献
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Tae Chul Hong Kunseok Kang Bon‐Jun Ku Dae‐Ig Chang 《International Journal of Satellite Communications and Networking》2017,35(1):3-15
For the successful deployment of the long term evolution (LTE)‐based mobile satellite service, the price of a user terminal is one of the major factors. A user terminal for the LTE‐based satellite communication needs to be implemented with a similar hardware size that is used for a terrestrial LTE user terminal. However, for quality of service provision, the satellite user terminal needs a larger size of memories than the terrestrial terminal does. This is very evident by considering that the N‐channel stop and wait hybrid automatic repeat request requires proportionally increasing memory size by the propagation delay, resulting in unmanageable amount of memories in the satellite system. To resolve this problem, we propose an efficient memory management method at the user terminal when the size of memory is insufficient. The simulation results in this paper reveal that the proposed method can increase the throughput about 20.7% when a user terminal is operated under very low throughput condition with an insufficient memory size, compared with the case without memory management scheme. In addition, we show that the additional throughput gain can be obtained by the packet scheduling using the information of receiver memory status. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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多终端协同接入网络选择算法研究 总被引:1,自引:0,他引:1
针对"虚拟终端"中多个终端设备协同工作时的接入网络选择问题,介绍了提供虚拟终端功能的网络结构;研究了多终端协同工作时业务的提供方法;分析了多终端同时接入时网络选择参数的变化情况;通过对已有多属性决策算法的改进,提出了多终端协同的接入网络选择(CANS)算法,实现了接入网络选择结果具有整体最优化。仿真结果表明,协同接入网络选择算法与随机接入网络选择法相比,业务吞吐量得到显著提高。 相似文献
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Gang Sun Hongfang Yu Vishal Anand Lemin Li Hao Di 《Photonic Network Communications》2012,24(2):118-131
Today applications and services are migrating to a cloud-computing-based paradigm in which the users access the applications and services hosted in data centers, by using thin-clients on the user terminal device. These applications/services are typically hosted and run on virtual machines in interconnected data centers. Different applications from the same user may need to access and change shared data or information. Thus, we may abstract the applications from same user as a virtual network (VN). For better performance and efficiency, it is critical that the VN request be accommodated with optimal provisioning under the current resource state of data centers. In this paper, for addressing the issue of how to design an optimal provisioning scheme for the VN request such that the total revenue of is maximized, we first develop a framework for the optimal provisioning of VN request by using mixed integer programming. Since the optimal provisioning problem is NP-hard, we also propose a genetic algorithm?Cbased heuristic algorithm for addressing the problem of optimal provisioning for VN with unsplittable flow and optimal provisioning for VN with splittable flow problems. We demonstrate the effectiveness of our approach in improving the total revenue by conducting extensive simulations on different networks. 相似文献
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在深入分析研究、归纳总结各种传统网络服务的共性机理与理论的基础上,设计构思基于一体化网络的普适服务总体模型体系,创建了服务标识机制与理论,完成对各种网络服务的统一描述和标识,以实现多种服务的统一处理;建立连接标识机制与理论,有效解决了普适服务的移动性和安全性问题,并在此基础上给出新传输协议,以支持语音、数据等多种服务;提出服务标识解析映射和连接标识解析映射机理与理论,实现了一体化网络下的服务多连接建立和多路径传输;最后通过原型系统实现和仿真分析证明普适服务机理和理论的正确性、有效性和可行性. 相似文献