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Inrecent years ,IEEE802.11 wirelesslocal area net-work (WLAN) has emerged as a prevailing technology forthe (indoor) broadband wireless access to internet for themobile/portable devices . In IEEE 802.11 standards ,802.11b has become the most widely used v… 相似文献
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提出了一种以 FA RIMA( p,d,q)模型为基础 ,对 MPEG VBR业务在综合业务网络传输的带宽进行动态分配的新方法 .FARIMA( p,d,q)模型既可描述业务的长相关特性 ,又可描述业务的短相关特性 ,以其为基础的业务预测较准确 .文中对建模和预报方法进行了简化 ,并通过仿真进行了验证 .结果表明本方法可减少对缓冲区的需求 ,并减少了丢包率 相似文献
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In wireless networks, data packets are lost due to channel interference and fading rather than network congestion. Thus, TCP designed for wired networks, cannot achieve a satisfying performance in wireless networks. Utilizing a cross-layer mechanism to identify the course of packet loss, we have proved that a mobile-host-centric transport protocol (MCP) can achieve higher throughput than TCP Reno and New Reno in static wireless environment. In this paper, we extend the cross-layer feedback mechanism and con... 相似文献
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Cross-layer design of energy-saving AODV routing protocol 总被引：1，自引：0，他引：1
Since most ad hoc mobile devices today operate on batteries, the power consumption becomes an important issue. This paper proposes a cross-layer
design of energy-aware ad hoc on-demand distance vector (CEAODV) routing protocol which adopts cross-layer mechanism and energy-aware metric to improve
AODV routing protocol to reduce the energy consumption and then prolong the life of the whole network. In CEAODV, the link
layer and the routing layer work together to choose the optimized transmission power for nodes and the route for packets.
The link layer provides the energy consumption information for the routing layer and the routing layer chooses route accordingly
and conversely controls the link layer to adjust the transmission power. The simulation result shows that CEAODV can outperform
AODV to save more energy. It can reduce the consumed energy by about 8% over traditional energy-aware algorithm. And the performance
is better when the traffic load is higher in the network. 相似文献
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本文描述具有图形建模与动画显示能力的ＲＴＳＳ仿真软件．软件由仿真内核、建模程序和结果后处理程序３部分组成，它可以在客户／服务器方式下运行．ＲＴＳＳ软件采用面向对象技术以增加灵活性，因此具有模块化、灵活性强、易于改进升级等特点．ＲＴＳＳ所建的系统模型是一个开放式队列网络．使用ＲＴＳＳ可对数据采集系统、通信网络以及柔性制造系统进行不同等级的模拟，因而是系统性能分析的有效工具 相似文献
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The cumulative sum （CUSUM） algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum con- tention window size of I 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated： a single-hop network with nodes spreading out in 100 m~100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m~ 1 000 m. The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
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以HT－7数据处理系统向分布式处理升级为例,描述了RTSS仿真为基础的系统性能评价技术．仿真与分析结果都表明客户／服务器工作方式比传统的分时方式性能有很大提高．客户／服务器方式使得在线系统的数据显示时间、实时数据处理时间和数据传输时间都大大缩短,提高了离线系统的负载处理能力,并降低了离线系统的平均系统等待时间． 相似文献
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Analysis of Network Traffic with Extreme Value Theory 总被引：1，自引：0，他引：1
Withincreasingdemandofwidebandwidthservicesuchasmultimediaandvideo ,itisverydesirabletore searchondifferenttransporttechniquesforhigh speednetworks.Congestioncontrol,bandwidthassignment ,networkmanagementand performanceevaluationaresomeexamplesthathavebeenresearchedwidely .Asthefoundationoftheseresearchfields ,itisthemostessentialtobuildamodelthatcanaccuratelycharacterizerealnet worktraffic .Hence ,itisalsonecessarytounderstandandanalyzestatisticalpropertiesofthenetworktrafficbecauseitcanindic… 相似文献
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In the IEEE g02. 11 protocol, the adoption of the exponential backoff technique leads to throughput performance strongly dependent on the initial contention window size and, most importantly, on the number of contending stations considered in the network. This paper proposes a simple but accurate method to dynamically estimate the number of contending stations in a wireless local area network （ WLAN ）. Based on estimation, all the mobile stations dynamically adjust the initial contention window in medium access control （ MAC ） layer to avoid collisions. The simulation results show that the proposed algorithm can achieve efficient channel utilization, higher system throughput, and better fairness performance. 相似文献
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This paper proposes a modification to distributed coordination function (DCF) to improve the channel utilization in IEEE 802.11 wireless local area networks (WLANs). In the modified DCF, when a station has contended for the channel, it may transmit multiple data frames continuously to the same destination, which is called transmission burst(TB). When the maximum number of data packets transmitted continuously in a TB is set to be 2, the performance is expected to be the best. The theoretical analysis and simulation results show that compared with the standard DCF, the modified DCF can increase the throughput and decrease the delay of the WLAN, and the modification does not introduce any additional control overhead. 相似文献
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