共查询到17条相似文献，搜索用时 171 毫秒
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本文介绍了移动IP的基本概念和IP的切换问题,分析了影响切换时通信性能的3个因素:移动检测、重新注册以及与上层协议的相互作用,提出了新的切换方案:将链路标识嵌入到FA的代理广播消息中,使得MN可以据此进行快速的移动检测;MN为发送端时,切换后主动发送未应答的TCP包;MN为接收端时,切换后通过主动发送多个TCP SACK包来请求发送端发送已丢失的TCP包。 相似文献
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常献刚 《商丘师范学院学报》2007,23(6):89-93
移动IPv6快速切换是解决移动IPv6切换过程中包丢失问题的互联网标准.快速切换通过在接入路由器间建立临时隧道,当移动节点切换时,用隧道来转发发向旧转发地址的数据包,同时允许接入路由器缓存发向移动节点的数据.本文分析了移动IPv6切换时丢包的原因,并提出解决方案.最后针对移动IPv6快速切换,分析其适合解决移动IPv6切换丢包的原因. 相似文献
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SDN网络思想为解决传统网络中网络层移动性管理面临的问题提供了新的解决思路,而SDN中现有的移动性管理方案仍面临用户移动过程中网络开销大和切换时延长等问题。研究在SDN网络中支持IPv6网络层移动性管理机制,通过对移动感知和移动切换两个关键技术进行分析设计,并结合位置预测理论提出了一种SDN网络中支持预切换的IPv6移动性管理机制。该机制根据位置预测结果在移动发生前计算并下发切换路径流表,降低了移动节点在移动过程中的信令开销和切换时延。最后根据性能评估分析方法,与同样基于SDN实现的OPMIPv6 C方案在信令开销和切换时延两方面进行了比较。 相似文献
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李江洪 《柳州职业技术学院学报》2006,6(2):77-81
无线接入点是无线接入网络的关键设备,负责对移动主机进行管理以及协调无线网络与有线网络之间的通信。本文通过分析IEEE 802.11.IEEE 802.3等协议和Internet工程部的有关建议,从硬件和软件结构两方面设计并实现了无线接入点系统。同时为了使移动节点在无线局域网中进行快速有效的切换,提出了快速移动切换方案,减少了移动节点内的切换过程的注册时延和数据包的丢失。 相似文献
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基于站的IEEE 802．11b／g无线局域网快速切换方案 总被引：1，自引：0，他引：1
由于实时应用对传输时延和抖动相对敏感,为减小WLAN切换过程对实时应用的影响,研究了WLAN切换过程的3个方面：触发切换,AP选择和快速切换算法．充分考虑到方案的可部署性和可扩展性,提出了一个以终端站为中心的快速切换方案．设计实现了基于动态阈值的切换触发机制、基于探寻时延的AP选择机制和信道区分选择结合动态缓存的快速切换算法．该方案完全在站上实现,不需要AP的配合或者对协议进行修改,因而具有良好的鲁棒性和可部署性．通过在实际的hotspot WLAN环境下测试和分析,该快速切换方案有效地减小了切换时延,同时使用户获得的实时应用网络性能有所增强． 相似文献
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基于Linux的802.11b无线网络MAC层切换的分析和实现 总被引：1，自引：0，他引：1
切换过程对无线移动网络质量有重大的影响,而现阶段的802.11b/g对切换的支持并不理想.文章从理论上分析了802.11b无线网络MAC层切换原理和过程,根据造成切换延迟和丢包的因素,提出了切换算法的改进策略,并且基于Linux系统和开源代码对该算法完成了软件实现.实验结果表明,改进算法可有效提高无线网络MAC层切换的速度. 相似文献
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第三代移动通信系统与第二代移动通信系统的一个主要区别在于第三代移动通信系统能够向用户提供中高速的数据业务.在空中接口上,CDMA2000系统能够在1.25MHz的带宽上提供高达304kbps速率的数据业务.在核心网部分,CDMA2000系统采用了基于IP技术的分组网络结构,通过互联网向用户提供WWW浏览、收发电子邮件、文件下载、电子商务和多媒体业务等各种业务.介绍了移动IP的工作机制和在3G移动通信系统CDMA2000中的实现方式,并结合移动通信系统的特点对移动IP和简单IP进行了比较. 相似文献
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移动IP网络中移动节点的移动会产生切换延迟。本文探讨了在HMIPV6下进行MAP分层的方案，可以适当减小移动节点在MAP中切换的平均延迟。 相似文献
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郭秦 《西安文理学院学报》2006,9(4):57-60
详细描述了移动IP的工作过程与机制,并介绍了移动IP实现的关键技术,最后对IPV6中移动IP新特性进行了论述.提出移动IP功能实体及隧道、家乡代理、转交地址等相关概念,然后对移动IP的做了详细的介绍,从而解决了Internet的可扩展性依赖于网络前缀路由和固定网络中的网络前缀路由技术没有办法将数据包发送到节点的新位置上的问题.最后总结了移动IP目前存在的问题和不足. 相似文献
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本提出了移动通信越区优先动态信道保留及排队算法(DCA-GC-QH)并加以深入研究，通过建立M／M／M／T马尔可夫链模型，以及通话阻塞率和越区通话中断率的动态建模，从而进一步优化信道分配。与固定信道策略相比，动态信道保留及排队策略的通话阻塞率和越区掉话率分别下降了约20％和30％。理论分析和仿真结果相符合。 相似文献
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ＳＯＦＴＨＡＮＤＯＦＦＡＬＧＯＲＩＴＨＭＢＡＳＥＤＯＮＳＩＧＮＡＬＬＥＶＥＬＳＴＲＥＮＧＴＨＳｉＹｉ（侣毅）ＣｈｅｎｇＳｈｉｘｉｎ（程时昕）（ＤｅｐａｒｔｍｅｎｔｏｆＲａｄｉｏＥｎｇｉｎｅｅｒｉｎｇ）ＳＯＦＴＨＡＮＤＯＦＦＡＬＧＯＲＩＴＨＭＢＡＳＥＤ... 相似文献
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INTRODUCTION With the emergence of wireless technology, various multimedia services, e.g., audio and/or video, are reaching us today through portable devices any- time, anywhere and even more increasingly accessi- ble in the near future. High quality video streaming over wireless IP is one of the most attractive applica- tions by ongoing deployment of wireless local area network (WLAN) hotspots and even powerful Wi- MAX mobile coverage. However, the present Internet is not providing a… 相似文献
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In this work, we present an evaluation of the performance and error robustness of RTP-based broadcast streaming of high-quality high-definition (HD) H.264/AVC video. Using a fully controlled IP test bed (Hillestad et al., 2005), we broadcast high-definition video over RTP/UDP, and use an IP network emulator to introduce a varying amount of randomly distributed packet loss. A high-performance network interface monitoring card is used to capture the video packets into a trace file. Purpose-built software parses the trace file, analyzes the RTP stream and assembles the correctly received NAL units into an H.264/AVC Annex B byte stream file, which is subsequently decoded by JVT JM 10.1 reference software. The proposed measurement setup is a novel, practical and intuitive approach to perform error resilience testing of real-world H.264/AVC broadcast applications. Through a series of experiments, we evaluate some of the error resilience features of the H.264/AVC standard, and see how they perform at packet loss rates from 0.01 % to 5%. The results confirmed that an appropriate slice partitioning scheme is essential to have a graceful degradation in received quality in the case of packet loss. While flexible macroblock ordering reduces the compression efficiency about 1 dB for our test material, reconstructed video quality is improved for loss rates above 0.25%. 相似文献
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首先给出了一种远端天线单元选择的分析模型,并定义了分布式移动通信系统中2种类型的切换:小区内切换(intra-cell HO)和小区间切换(inter-cell HO);然后提出了一种小区间切换的模型,该模型利用激活集的平均功率强度来预测移动台(MS)的位置,通过比较激活集和切换集的总功率,来判断移动台是否需要进行一次越区切换.此外,在RAU选择的基础上,详细分析了2种切换方式中切换参数和切换性能指标之间的关系.仿真结果表明,通过合理地选择切换参数,2种切换方式都能够取得良好的性能. 相似文献
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In this work, we present an evaluation of the performance and error robustness of RTP-based broadcast streaming of high-quality high-definition (HD) H.264/AVC video. Using a fully controlled IP test bed (Hillestad et al., 2005), we broadcast high-definition video over RTP/UDP, and use an IP network emulator to introduce a varying amount of randomly distributed packet loss. A high-performance network interface monitoring card is used to capture the video packets into a trace file. Purpose-built software parses the trace file, analyzes the RTP stream and assembles the correctly received NAL units into an H.264/AVC Annex B byte stream file, which is subsequently decoded by JVT JM 10.1 reference software. The proposed measurement setup is a novel, practical and intuitive approach to perform error resilience testing of real-world H.264/AVC broadcast applications. Through a series of experiments, we evaluate some of the error resilience features of the H.264/AVC standard, and see how they perform at packet loss rates from 0.01% to 5%. The results confirmed that an appropriate slice partitioning scheme is essential to have a graceful degradation in received quality in the case of packet loss. While flexible macroblock ordering reduces the compression efficiency about 1 dB for our test material, reconstructed video quality is improved for loss rates above 0.25%. 相似文献
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Classical unequal erasure protection schemes split data to be protected into classes which are encoded independently. The unequal protection scheme presented in this paper is based on an erasure code which encodes all the data together according to the existing dependencies. A simple algorithm generates dynamically the generator matrix of the erasure code according to the packets streams structure, i.e., the dependencies between the packets, and the rate of the code. This proposed erasure code was applied to a packetized MPEG4 stream transmitted over a packet erasure channel and compared with other classical protection schemes in terms of PSNR and MOS. It is shown that the proposed code allows keeping a high video quality-level in a larger packet loss rate range than the other protection schemes. 相似文献