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介绍了红外无线MODEM通信系统的组成和利用Visual C 的MFC(微软基础类库)开发的应用程序,该应用程序实现了软件的CRC校验,肯定确认的重传协议,实现了Windows平台下所有文件的可靠传输。 相似文献
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为解决卫星链路上的大延迟环境对GEO移动通信协议RLC层应用现有选择重传机制(SR-ARQ)造成吞吐量低下的问题,提出了适用于GEO卫星移动通信协议RLC层的HARQ重传机制(G-HARQ),并在QualNet平台上对GEO卫星移动通信协议RLC层G-HARQ和SR-ARQ吞吐量进行仿真实验.仿真结果表明,G-HARQ重传机制可以减少RLC确认模式下为恢复错误数据包而传送的ACK/NACK消息数量,从而降低在GEO卫星移动通信协议RLC层端到端的总延迟,提高RLC层吞吐量. 相似文献
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提出了部分窗口多拒绝选择重传(ARQ)协议,有效的提高确认效率,提高系统吞吐率、减小链路时延和时延抖动,从而节省了宝贵的无线资源.模型分析及仿真结果表明,此协议很好地适应了无线链路大时延、高误码率的特点. 相似文献
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针对FSO/RF混合链路的高效可靠数据传输问题,研究系统在二进制相移键控(BPSK)调制与ARQ差错控制模式下双链路重传协作的优化设计方法。基于FSO信道双伽马(Gamma-Gamma)分布的湍流模型和RF信道Nakagami-m分布的衰落模型,推导得出混合链路平均包错误率与吞吐量的解析表达式,并运用凸优化求解方法得出吞吐量最优解时的数据重传协作比例系数。在不同大气湍流强度与衰落因子条件下,计算分析了FSO/RF混合链路ARQ数传方案的平均包错误率与吞吐量性能。数值结果表明,采用优化后的ARQ双链路重传比例策略,可有效提高混合链路传输的可靠性与数据吞吐量性能。 相似文献
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为解决传统基于时延的MPTCP拥塞控制算法被动地等待重传超时或重复确认来确认链路拥塞,不能及时避免拥塞的问题,提出以满足多路径流公平性为基础,实施链路RT T主动探测,设计并实现一种基于排队时延主动探测的拥塞区分链路质量优化协议PPQD,以排队时延预测结果及其均值比较为依据实施拥塞窗口动态调整.实验结果表明,该方法可大... 相似文献
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许多研究者已经发现,在无线链路上使用链路层自动请求重传(ARQ)来恢复无线链路差错,会在无线链路上和TCP源端产生大量的突发性流,从而使路由器拥塞,导致分组丢失和吞吐量下降.本文提出了一种解决方案,在ARQ的接收端,利用漏桶对接收确认分组进行平滑,使分组的发送能保持一定的间隔.仿真结果表明,平滑能提供更好的吞吐量性能和更低的丢失率。 相似文献
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DACP协议是以PSTN和Modem为基础的点对点全双工异步串行通信数据传输协议,主要介绍DACP的体系结构、设计思想以及通信机制。详细说明DACP分组机制、DACP帧格式、字符插入技术和用环循队列模拟滑动窗口技术来实现选择重传连续ARQ协议,使信道获得较大吞吐量,提高数据传输速度,最后简述DACP协议应用。 相似文献
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研究基于介质访问控制协议(MAC)的分布式争用问题的主要焦点就是设计有效的具有高吞吐量性能的MAC协议。该文提出在无线局域网中基于MAC协议的有效争用方法,即改良的冲突解决算法(DCR)。该算法主要做了以下几方面的改良和创新:对所有现用网点主动的分配补偿时间,提高解决冲突的速度;当确定固定数量的连续空闲时间片被探测到时,对成功包传输的站点使用较小的争用窗口,以指数级速度减少补偿时间片和减少空闲时间片的平均数。该文提出的改良冲突解决算法提供了高吞吐量性能和在局域网中的低执行时间。 相似文献
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IEEE 802.11 specifies a network technology for wireless local area networks (LANs) and mobile user connections. The fundamental access mechanism in the IEEE 802.11 MAC protocol is the Distributed Coordination Function (DCF). The throughput of LANs with the DCF mechanism under high load and in noise is evaluated by an analytical method, which ensures high estimation accuracy for any values of protocol parameters and bit error rates. 相似文献
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高明成 《数字社区&智能家居》2009,(30)
首先介绍了OSPF(Open Shortest Path First开放最短路径优先)路由协议,接下来介绍了OSPF的HELLO报文、DD报文、LSR报文、LSU报文、LSAck报文等5种报文以及OSPF协议计算路由的过程。针对OSPF的攻击与防范问题,介绍了基于LSA(链路状态广播)攻击的基本原理及基本防范方法。 相似文献
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WAP2.0协议栈新特点及基于GPRS的应用分析 总被引:1,自引:0,他引:1
无线应用协议2.0与通用分组无线业务,为无线Internet业务带来了新技术和发展的巨大潜力,本文探讨了WAP2.0协议栈的新特点,介绍了GPRS系统以及基于其上的WAP应用。 相似文献
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《Computer Standards & Interfaces》2007,29(3):289-301
This paper presents an overview and analysis of Extensible Authentication Protocol (EAP) and its place in securing wireless LANs. A number of specific widely used EAP methods are examined and evaluated for their advantages and susceptibility to types of attack. Next we propose suitable EAP methods for wireless technologies beyond LANs, including RFID and WiMAX. After analyzing requirements for different wireless networks, we conclude that a new lightweight and secure EAP method is warranted for fixed mobile convergence interoperability. 相似文献
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ODMRP协议是无线自组网环境下的一种按需式组播路由协议。论文提出了一种基于链路状态预测的ODMRP协议改进,即LSF-ODMRP路由协议。该协议继承了ODMRP协议的按需式路由发现和更新,并采用了链路状态预测机制LSF(Link Status Forecasting),大大减少了路由失效数并缩短了分组投递延迟,提高了网络性能。通过对LSF-ODMRP协议的模拟仿真实验比较,验证了协议的改进效果。 相似文献
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Jansi Rani Sella Veluswami 《计算机系统科学与工程》2022,43(3):1231-1239
Most of the internet users connect through wireless networks. Major part of internet traffic is carried by Transmission Control Protocol (TCP). It has some design constraints while operated across wireless networks. TCP is the traditional predominant protocol designed for wired networks. To control congestion in the network, TCP used acknowledgment to delivery of packets by the end host. In wired network, packet loss signals congestion in the network. But rather in wireless networks, loss is mainly because of the wireless characteristics such as fading, signal strength etc. When a packet travels across wired and wireless networks, TCP congestion control theory faces problem during handshake between them. This paper focuses on finding this misinterpretation of the losses using cross layer approach. This paper focuses on increasing bandwidth usage by improving TCP throughput in wireless environments using cross layer approach and hence named the proposed system as CRLTCP. TCP misinterprets wireless loss as congestion loss and unnecessarily reduces congestion window size. Using the signal strength and frame error rate, the type of loss is identified and accordingly the response of TCP is modified. The results show that there is a significant improvement in the throughput of proposed TCP upon which bandwidth usage is increased. 相似文献
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MAC协议是无线传感器网络协议的重要组成部分,网络的性能(如吞吐量、容量、时延及功耗等)依赖于所采用的MAC协议,也是无线传感器网络设计研究的主要技术难点之一。该文指出了无线传感器网络MAC协议设计的主要问题,对几种典型的MAC协议进行了分析和研究,并分析研究了无线传感器网络MAC协议的研究与应用方向。 相似文献
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本文叙述了蓝牙无线连接在射频、基带协议、链路管理协议(LMP)中采用的可靠性措施.特别是,本文作者对提高蓝牙文件传输的可靠性做了深入的研究,在蓝牙RFCOMM协议的基础之上建立了本文所描述的蓝牙的文件传输协议,称之为RBTFT,其中,创造性地提出了支持文件断点续传的办法.并得到了实现,从而在应用层有效地提高了蓝牙无线连接的可靠性. 相似文献
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Wenjun Xu Author Vitae Zude Zhou Author Vitae Author Vitae C. Ji Author Vitae Author Vitae Quan Liu Author Vitae 《Journal of Systems and Software》2010,83(12):2642-2652
Currently there is no control for the real-time traffic of multimedia applications using UDP (User Datagram Protocol) in high-speed networks. Therefore, although a number of high-speed TCP (Transmission Control Protocol) protocols have been developed for gigabit-speed (or faster) links, the real-time traffic could also congest the network and result in unfairness and throughput degradation of TCP traffic. In this paper, a new unreliable transport protocol, FAST DCCP, is presented for the real-time traffic in high-speed networks. FAST DCCP is based on the DCCP protocol and adopts the FAST scheme to realize congestion control. Some modifications have been made to the mechanisms inherited from DCCP so as to let the proposed protocol can efficiently operate under a large size window. In addition, an enhanced protocol, EEFAST DCCP, using the measurements of one-way delay to dynamically adjust the window size is also proposed to improve the throughput of FAST DCCP with the effect of reverse traffic. Simulation results show that FAST DCCP not only can satisfy the requirements of real-time data delivery, but also perform well in bandwidth utilization and fairness in high-speed networks. Meanwhile, EEFAST DCCP is able to effectively conquer the throughput degradation caused by the reverse traffic. 相似文献