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As third-generation (3G) wireless networks with high data rate get widely deployed, optimizing the transmission control protocol (TCP) performance over these networks would have a broad and significant impact on data application performance. In this paper, we make two main contributions. First, one of the biggest challenges in optimizing the TCP performance over the 3G wireless networks is adapting to the significant delay and rate variations over the wireless channel. We present window regulator algorithms that use the receiver window field in the acknowledgment (ACK) packets to convey the instantaneous wireless channel conditions to the TCP source and an ACK buffer to absorb the channel variations, thereby maximizing long-lived TCP performance. It improves the performance of TCP selective ACK (SACK) by up to 100 percent over a simple drop-tail policy, with small buffer sizes at the congested router. Second, we present a wireless channel and TCP-aware scheduling and buffer sharing algorithm that reduces the latency of short flows while still exploiting user diversity for a wide range of user and traffic mix. 相似文献
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Mobile IP中的切换将会导致数据包的丢失。平滑切换避免了数据包的丢失,却可能导致数据包的失序。文章分析了已有的减少失序数据包的方案的不足,提出了新的改进方案,并进行了评估,证明了其优越性。 相似文献
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TCP/IP网络的动态模型描述 总被引:2,自引:0,他引:2
拥塞现象成为TCP/IP网络发展面临的一个重要问题。因此,拥塞控制对TCP/IP网络的鲁棒性和稳定性具有重要作用。目前,网络拥塞控制策略主要包括两类:端到端的控制机制,如TCP拥塞控制算法;网络内部的主动队列管理(AQM)策略。但由于缺乏对网络系统动态特性的了解,这些拥塞控制策略大都基于专家经验,并没有建立完整的理论分析框架。为此,本文从数据流的角度出发,通过建立网络基本单元状态方程模型来实现IP网络系统的数学解析模型,然后用混杂系统来描述TCP带有拥塞控制策略的数据传输过程,建立了TCP/IP网络的动态模型,为网络系统中动态性能的分析、拥塞控制策略的设计奠定了基础。实验结果表明,该数学模型与NS仿真实验的结果相一致。 相似文献
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应用复杂网络理论,针对TCP/IP协议簇的内在关系,以协议规范文档为节点。协议间的引用关系为边,构造网络图并分析其节点度分布、平均最短路径和群集性质。研究发现,协议间的引用关系具有复杂网络的基本特征:幂律分布、小世界效应和大群集效应。图分割计算的结果,表明协议间互引用关系网络比分层结构具有更丰富的局部特征。 相似文献
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文章介绍了几种实用化的快速IP流分类技术,如三重内容寻址、基于比特向量的多维范围匹配、有向非循环图、交叉乘积和递归流分类算法等流分类技术,并根据各种流分类技术的不同应用场合,给出了设计分类算法的原则。 相似文献
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当前在Internet和其他计算机网上广泛使用的TCP/IP协议与未来准备在B-ISDN上应用的ATM技术之间的有机结合,是一个战略性的技术课题。本文以TCP/IP协议的体系结构及其作用、ATM信号元结构与ATP适应层为依据,对IP与ATM适配的种种构想(其中包括协议复用、封装、地址分辨和连接管理等项功能的实现)做了轮廓性的探讨。 相似文献
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无线信道的特点数据在信道上从发送端发出到接收端完全收到的总传送时延 (DeliveryDelay)=发送时延(Transmission Delay)+传播时延(Propagation Delay),其中发送延迟的大小为数据长度除以数据在信道上的发送速率;传播时延为电磁波信号从链路的一端传到另一端的时间,它取决于电磁波信号在信道上的传播速度和信道的长度。在有线网络中,较高的带宽使得发送时延 (从以太网中的10Mb/s到大型网络骨干网的10Gb/s)相对较小,在移动通信系统的无线信道中,在信道长度一定时,传播时延相对固定,因此小带宽引起的较大的发送时延决定了总的发送… 相似文献
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分析了TCP有关拥塞控制的假设在无线和移动IP中的不正确性,由此对TCP协议提出了一些修改方法,以改善TCP在无线和移动点中的性能。 相似文献
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《IEEE network》2007,21(4):8-14
Although IP is widely recognized as the platform for next-generation converged networks, unfortunately, it is heavily burdened by its heritage of almost 30 years. Nowadays, network operators must devote significant resources to perform essential tasks, such as traffic engineering, policy enforcement, and security. In this article, we argue that one of the principal reasons for this is the way control and forwarding planes are interspersed in IP networks today. We review the architectural developments that led to the current situation, and we reason that centralization of network control functionality can constitute a solution to the pressing problems of the contemporary Internet. 相似文献
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Optical packet assembly is a key function to support inter-working between TCP/IP networks and optical packet-switched networks.
It is characterized by the assembly delay and by the segment aggregation needed to form an optical packet. These counter-balancing
aspects depend on several environment variables, such as the TCP parameters, the access link speed, the optical packet size
whose effects are studied in this paper. Performance evaluations are obtained by extensive simulations in terms of send rate
of TCP flows, fairness, efficiency, and assembly delay. Some guidelines in the design of optical packets that take into account
the results presented are given. 相似文献
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通过电台组网通信在特殊场合具有十分重要的应用价值.电台一般采用半双工方式通信,这种环境下TCP/IP的适用性及其性能值得研究.NS是网络模拟常用的工具,但它本身并不包含半双工链路模型.文中首先讨论在NS网络仿真软件中对半双工链路的建模,进而研究TCP/IP在半双工信道上的性能.模拟实验结果表明:只要解决半双工信道的信息冲突问题,TCP/IP在半双工链路上运行是完全可行的. 相似文献
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Service discovery is critical to maintaining the privacy of clients and service providers. Individuals often disclose personal information when looking for services, or intruders can deduce this information from historical discovery data, so service-discovery protocols need to protect it from illegitimate access. Privacy-aware service-discovery protocols, however, must still be flexible and scalable so that they can support the requirements of service-oriented pervasive computing. We present EVEY (enhancing privacy of service discovery), a privacy-aware service-discovery protocol that supports syntactic and semantic matching between service requests and advertisements. It protects private information related to service discovery by introducing ambiguity in both service advertisements and service requests so that they can represent a group of services instead of a single, specific service instance. 相似文献
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在Windows 95客户机中,由于安装的是调制解调器,支持拨号上网的连接访问,不需要安装一个物理网卡,而只需安装一个逻辑网络接口卡,处理与Modem的信息传递. 相似文献