共查询到19条相似文献,搜索用时 125 毫秒
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随着网络技术的发展,网络拥塞日益严重,如何解决拥塞,充分、高效地利用网络资源,成为当今急需解决的问题.由于Internet上大多数业务都采用TCP协议,因此TCP的拥塞控制机制对控制网络拥塞具有特别重要的意义.本文介绍了TCP基于窗口的拥塞控制策略和目前常用端到端拥塞控制算法,并对它们的性能进行比较. 相似文献
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基于神经网络的多路无线TCP均衡控制算法 总被引:1,自引:1,他引:0
针对无线网络应用,能够有效地使多路的TCP数据业务均衡地使用网络共享资源,需要系统能根据无线网络的容量实时变化,动态调整各路TCP协议拥塞窗口大小,其参数结构复杂,难于建立精确的数学模型。为此提出了一种基于BP神经网络的控制算法,利用它可有效解决多路无线TCP数据业务拥塞窗口的自适应控制问题,为基于无线网络数据业务应用的优化提出一种新的思路。 相似文献
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为了提高网络运行效率,提出了一种采用RTP/RTCP协议基于模型的的类TCP拥塞控制算法.算法采用TCP确认机制,对流量参考模型、往返时间及超时时钟值等参数进行了定义;使用改进的AIMD机制进行窗口控制,调整RTP数据帧的传输速率;同时彻底摒弃TCP的重传机制以保证流媒体业务的连续性和实时性.实验结果表明,提出的算法与其他RTP流控算法相比,具有较好的拥塞控制能力和公平性. 相似文献
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文章模拟了两个建筑楼中移动无线节点之间的数据传送情况,探讨TCP拥塞窗口控制机制在移动无线网络中的应用效果。针对具体的应用,提出了移动无线网络中TCP拥塞窗口控制机制的仿真思路,并用NS3模拟器进行了具体的仿真实现。 相似文献
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TCP(传输控制协议)拥塞控制机制直接使用在卫星网中存在很多不足。针对卫星网通信时延长、网络环境变化复杂的特点,利用TCP协议中的时间戳扩展选项,设计实现了一种改进的TCP重传和拥塞控制算法,能够根据RTr(Round Trip Time,往返时间)的变化对网络情况进行预测,从而及时重传数据包并调整窗口大小,仿真实验证明改进算法能够很好地提高TCP性能。 相似文献
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传统TCP(传输控制协议)拥塞控制协议本是为有线网络设计,它假设包丢失完全是由网络拥塞引起。在无线网络环境下除了拥塞丢包外,还存在较高的比特误码率、路由故障等因素引起的丢包现象。当出现非拥塞丢包时,传统TCP将错误地触发拥塞控制,从而引起TCP性能低下。文章在分析传统TCP在无线网络中存在问题的基础上,对目前无线TCP发展和技术进行归纳和比较,进一步给出无线传输协议的研究和发展方向。 相似文献
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为提升计算机的网络性能,更好地避免拥塞现象的发生,需要对其进行必要的技术控制。鉴于此,对基于TCP/IP协议的网络拥塞控制方法进行分析。在TCP拥塞控制中主要采用TCP Tahoe,TCP Reno,TCP New Reno以及TCP Sack四种方法,其中TCP New Reno对快速恢复算法进行了改进,通过对TCP协议中的Reno进行可视化处理,实行对网络拥塞的有效管理。而IP拥塞控制方法则分为FIFO,FQ和WFQ,RED以及ECN四种类型,通过队列调度管理方式实现了对网络拥塞的有效管理。 相似文献
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There has been a spectacular growth in the use of wireless networks in recent times and consequently, adapting TCP to the
wireless networks is a hot topic of current research. However, most of the existing works proposed for this problem have been
designed for specific wireless networks, or they necessitate changes at either the receiver or the intermediate nodes, or
at both, because of which their deployment becomes difficult. In this work, we propose a TCP variant which works over both
multi-hop ad hoc wireless networks as well as single-hop (last-hop) wireless networks, like Wireless LANs, cellular, and satellite
networks. We use a learning based method to dynamically change the congestion window size according to the network conditions.
Our protocol does not rely on any explicit feedback from the network and requires only sender-side modifications. Through
extensive simulations we show that our protocol achieves the desired goals of performance improvement in goodput, reduction
in packet loss, and fairness to the competing flows. To the best of our knowledge, this is the first unified solution for
both single-hop and multi-hop wireless networks. 相似文献
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Ji-Cheol Moon Byeong Gi Lee 《Networking, IEEE/ACM Transactions on》2006,14(3):603-615
We study TCP performance over the wireless links deploying a wireless rate-control technique, whose link characteristics are identified by variable link rate and bursty transmission error. We present a TCP enhancement scheme, called rate-adaptive snoop (RA-Snoop). RA-Snoop caches TCP packets selectively based on the wireless channel condition and the cached packets are retransmitted locally over the wireless link in case corruption loss is detected. In addition, for effective adaptation to variable bandwidth, RA-Snoop calculates the window feedback based on the bandwidth-delay product estimation and the queue level, then conveys this feedback information on the receiver's advertised window field in the acknowledgements returning to TCP sources. We compare the performance of RA-Snoop with that of existing schemes in the aspect of goodput and fairness. Results from simulations reveal that RA-Snoop achieves significant improvements over the existing schemes for various traffic scenarios. 相似文献
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文章在分析现有提高无线TCP性能方案的基础上,提出一种新的流量控制方法,即基于显式窗口反馈的无线网络流量控制方案。在Snoop中引入有线网络的显示窗口自适应(EWA)算法,通过对BS共享缓存的实时监测,应用模糊控制算法预测当前拥塞窗口(cwnd)的大小,并显式反馈给发送端,使TCP的发送窗口能快速响应网络负荷状况的变化.避免分组的丢失。仿真结果表明.该方法增强了网络对拥塞的自适应性以及对无线信道差错的实时处理能力.提高了网络的吞吐量。 相似文献
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《Mobile Computing, IEEE Transactions on》2008,7(7):898-911
In this paper, we investigate the issue of per-station fairness in TCP over IEEE 802.11-compliant wireless local area networks (WLANs), especially in Wi-Fi hot spot. It is asserted that the hot spot suffers from the unfairness among stations in exploiting the wireless medium. The source of this unfairness is analyzed from two aspects, TCP-induced asymmetry and MAC-induced asymmetry; the former causes TCP congestion control with a cumulative acknowledgment mechanism to prefer the sending stations to receiving stations, while the later exacerbates the unfairness problem in the hot spots. We investigate the interaction between TCP congestion control and MAC contention control, and propose a cross-layer feedback approach to assure per-station fairness and to ensure high channel utilization. In this approach, we introduce the notion of channel access cost to quantify the system-wide traffic load and per-station channel usage. The access cost is estimated at the MAC in an access point and conveyed to the TCP sender. Then, the TCP sender adjusts its sending rate based on the access cost, so as to assure per-station fairness. The simulation results indicate that the proposed approach can provide both per-station fairness and high channel utilization, irrespective of network configurations. 相似文献
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TCP和IP协议非常简单且可靠,它们的组合决定了目前的大多数通信方式(从有线骨干网到混合网)。TCP协议最初是为有线网络而设计的,目前已成为大多数应用事实上的标准。在有线网络中随机比特差错率可以忽略,拥塞主要由包丢失造成。很多研究都表明未修改的TCP协议在无线环境中的性能很差,因为它无法区分数据包的丢失是由于拥塞还是传输差错造成的。文章分析了TCP在无线IP通信中存在的问题,详细给出了相应的解决方案。 相似文献
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Raed T. Al-Zubi Marwan Krunz Ghazi Al-Sukkar Mohammed Hawa Khalid A. Darabkh 《Wireless Personal Communications》2014,75(2):943-963
Most of the schemes that were proposed to improve the performance of transmission control protocol (TCP) over mobile ad hoc networks (MANETs) are based on a feedback from the network, which can be expensive (require extra bandwidth) and unreliable. Moreover, most of these schemes consider only one cause of packet loss. They also resume operation based on the same stand-by parameters that might vary in the new route. Therefore, we propose two techniques for improving the performance of TCP over MANETs. The first one, called TCP with packet recycling (TCP-PR), allows the nodes to recycle the packets instead of dropping them after reaching the retransmission limit at the MAC layer. In the second technique, which is called TCP with adaptive delay window (TCP-ADW), the receiver delays sending TCP ACK for a certain time that is dynamically changed according to the congestion window and the trip time of the received packet. TCP-PR and TCP-ADW are simple, easy to implement, do not require network feedback, compatible with the standard TCP, and do not require distinguishing between the causes of packet loss. Our thorough simulations show that the integration of our two techniques improves the performance of TCP over MANETs. 相似文献