共查询到18条相似文献,搜索用时 187 毫秒
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针对移动互联网用户的多终端协同的垂直切换问题,提出一种UMTS与WLAN异构网络环境下的多终端协同的垂直切换决策算法,其包含切换时间判断与多终端协同算法。首先利用模糊逻辑判断网络切换时机,然后综合考虑主观因素和客观因素,采用AHP(Analytic Hierarchy Process)合理定义权值并结合TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)实现不同接入策略的性能评价,为用户提供最佳QoE(Quality of Experience)的多终端协同方案。实验结果表明:所提方法和基于迟滞算法相比,切换次数平均降低7.9次,切换失败率平均降低2.25%;网络选择结果与应用需求和用户需求保持较好的一致性。实现了多终端协同用户在异构网络环境下高效实时的垂直切换。 相似文献
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针对现有PMIPv6域间切换出现时延较大的问题,基于PMIPv6域内切换和域间切换以及介质独立切换的特性提出一种基于IEEE 802.21MIH标准的增强型PMIPv6域间切换方法。方法通过L2的方法提前告知移动节点切换目标网络的方法代替L3的网络扫描将切换决策和执行时间点提前,增强网络的无缝切换,性能分析结果表明该增强技术能够减少整个网络时延和丢包率,改善了网络性能。 相似文献
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曲伟 《计算机光盘软件与应用》2012,(15):167+169
随着计算机技术的发展,人们对移动通信的需求也在不断增加,WLAN和3G网络的有效融合是现代移动互联网发展的重要方向。研究小范围、高带宽通信的WLAN和大范围、带宽有限的3G网络之间的切换是当前通信行业的重要课题。本文首先介绍了WLAN和3G的传统切换过程,分析其中存在的问题,然后在传统垂直切换过程的基础上提出改进方法:滑动平均值预测和坡度预测法。 相似文献
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充分挖掘网络资源的潜力,提出一种基于替代扫描的快速切换算法(substituted scan-based fast hand-off,SSBFH)。其核心思想是为WLAN中的移动设备维护一张可替代收集切换信息的移动设备信息表,当移动设备需要切换且处于数据交换时,可以利用该表选择合适的移动设备代替其完成大部分切换工作,不但缩短需要切换的移动设备的切换时间,而且保证正在进行的数据服务质量。从实验结果看出,SSBFH算法较标准的802.11切换算法,缩短切换时间,优化切换性能。 相似文献
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刘鑑澄 《计算机应用与软件》2009,26(6):218-223
针对无线局域网WLAN(Wireless Local Area Network)与蜂窝混合网络,提出一种具有抢占蜂窝网络信道的切换策略。当使用蜂窝信道的终端移入WLAN覆盖区域时,只有在该终端所使用的信道被抢占时,该机制才进行垂直切换以减少因切换造成的时延与丢包;建立了该切换策略的三维马尔可夫模型,分析了WLAN网络的终端数、蜂窝信道的利用率、信道接入请求阻塞率、信道抢占率与信道被抢占率的性能。详细的仿真结果证明了提出的模型的有效性,当WLAN覆盖面积比例为0.2时,信道抢占概率最大;当终端移动速度达到100km/h时,信道被抢占的概率是移动速度为20km/h的3倍;提出的信道切换策略与随机切换策略相比,显著地降低了业务的丢包率与传输时延。 相似文献
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在下一代异构网络环境中为移动用户提供无缝切换以及更优的体验质量是人们面临的一大挑战.尽管FMIPv6一定程度上减小了切换的时延,但还是存在切换发起时延过大,以及无法满足垂直切换的需求等缺点.提出了一种基于IEEE 802.21 MIH(与介质无关切换)服务的FMIPv6改进机制.利用MIH信息服务优化了接入路由发现以及接入点(AP)发现过程.利用MIH事件服务优化了FMIPv6的切换过程.通过性能分析可以发现,改进机制减小了切换发起时间增加了预应式切换的可能性,减小了AP发现时间,同时也减小了切换时延. 相似文献
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Chih-Peng LinAuthor Vitae Hsing-Lung Chen Author VitaeJenq-Shiou Leu Author Vitae 《Computers & Electrical Engineering》2012,38(3):681-693
The Media Independent Handover (MIH) standard defined in the IEEE 802.21 specification supports vertical handovers across heterogeneous networks. A cross-layer scheduling scheme is proposed to exploit Link Going Down information from MIH to predict handover requirements, and then improve the performance of Quality of Service (QoS) enabled transport services given the limited radio spectrum available for handovers in a heterogeneous network environment. According to simulation results, the proposed scheme can effectively increase the effective range of QoS sensitive services at the cell border while executing the handover procedure. 相似文献
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In this paper, we propose a framework for the implementation of the IEEE 802.21 Media Independent Handover (MIH) standard and evaluate its performance through experiments in integrated 802.11/802.16e networks. The IEEE 802.21 standard defines three types of MIH services (event, command, and information) that facilitate the mobility management and handover process in heterogeneous networks. To support MIH services, we develop a MIH-capable mobile node and the MIH information service server. Then, we introduce the Connection Manager (CM) which utilizes MIH services. Two main roles of CM are supporting seamless vertical handovers and efficient access point (AP) discoveries. From the experimental results in the real test-bed, we can know that the MIH services can be used to reduce packet losses during a vertical handover and to reduce the AP discovery time and energy consumption of mobile nodes. 相似文献
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Integration of various wireless access technologies is one of the major concerns in recent wireless systems in which multi-technology mobile devices are provided to users to roam between different access networks. Being an essential part in heterogeneous wireless systems, vertical handover is more complex than conventional horizontal handover. As IEEE 802.21 Media Independent Handover (MIH) is the standard addressing a uniform and media-independent framework for seamless handover between different access technologies, many works have been carried out in the literature to employ MIH services in handover management This paper presents a comprehensive survey of the proposed mobility management mechanisms that are using this framework. As a comparative view, the paper categorizes the efforts according to the layer of mobility management and evaluates some of the representative methods discussing about their advantages and disadvantages The paper also looks into recent handover decision and interface management methods that are exploiting MIH Moreover, the extensions and the amendments proposed on MIH are overviewed. 相似文献
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Jihun HaAuthor Vitae Jiung YuAuthor VitaeByungjo KimAuthor Vitae Hyogon Kim 《Computer Networks》2013,57(17):3563-3580
Today’s mobile devices such as smart phones are equipped with multiple wireless access technologies, so multi-radio operation is becoming the norm. These devices frequently face vertical handover scenarios such as exiting Wi-Fi hotspot towards cellular network coverage. Unfortunately, the vertical handover execution is still done in a very primitive way even with middleware support, and the reality is that any active service at the time of handover is aborted or at least severely disrupted when it happens. In this paper, we explore how the transport layer can independently overcome the disruption caused by the vertical handover and obtain service continuity with or without underlying vertical mobility support infrastructures such as Media Independent Handover (MIH) or Access Network Discovery and Selection Function (ANDSF). In particular, we focus on the case of User Datagram Protocol (UDP), and explore how to evolve it for vertical handover. In particular, we show that UDP can be enriched with options while keeping application transparency and enabling incremental deployment as is the case for Transmission Control Protocol (TCP). We implement the proof-of-concept prototype and demonstrate that it performs well under dynamic Cellular-WiFi vertical handover settings with off-the-shelf smart phones operating across commercial 3G cellular carriers and Internet Service Provider (ISP) networks. We also consider the ways to utilize the evolved UDP for other applications, as the addition of carrying options or in-band signaling capability opens a whole new horizon for the usability of UDP. 相似文献
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J. Jackson Juliet RoyAuthor Vitae V. VaidehiAuthor VitaeM.S. SricharanAuthor Vitae 《Computers & Electrical Engineering》2011,37(3):261-274
Wireless technologies which serve multimedia applications have to guarantee the Quality of Service (QoS) demands along with seamless connectivity. The complexity in attaining such demands increases if the network is heterogeneous in nature. This paper proposes a QoS guaranteed integration methodology for a heterogeneous wireless local area network (WLAN) - worldwide interoperability for microwave access (WiMAX) network. An integrated protocol stack for the mobile terminal which could work in a WLAN-WiMAX heterogeneous network is proposed. The proposed integrated protocol stack, a blend of two modules namely generic virtual link layer (GVLL) and media independent handover (MIH) is placed above the media access control (MAC) layer which includes both WLAN and WiMAX MAC. The impact of GVLL in guaranteeing the QoS on QoS deterioration and the impact of MIH in attaining seamless handover are analyzed and the results are presented. 相似文献
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无线蜂窝网的信号切换依赖IP层的移动切换,IETF提出的代理移动IPv6(PMIPv6)协议可以保证移动终端应用IPv6网的快速切换,但是它在切换时延方面仍然无法保证实时通信的服务质量。研究基于PMIPv6协议,提出群集移动节点(CMN)算法,应用媒体无关切换(MIH)技术,减少了大量移动节点,同时提出切换请求时系统时延增大的问题,扩展原始代理绑定更新消息结构(A-PBU)。最后模拟网络模型和节点移动模型,从切换时延方面分析算法的有效性。实验结果表明,系统应用CMN算法与原始切换算法相比可以大大降低切换时延。 相似文献