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无线网状网(Wireless Mesh Network,WMN)是一种新型的分布式宽带无线网络结构.典型的移动Ad Hoc网络具有节点移动性小、受电池动力限制和用户带宽需求大等特点,从而导致传统单信道的Ad Hoc结构不再满足WMN用户的需求.为了提供更大的带宽,多信道技术得到越来越多应用.探讨了WMN的网络结构与特点,对现有几种典型的多信道技术进行了比较,提出了一种基于单射频的无线Mesh网多信道的设计方案,不同网关节点所代理的节点使用不同的信道进行通信,从而避免了不同子网节点之间的信道干扰.通过NS2的仿真与分析表明,该方法在特定环境下的网络性能是传统单射频单信道方法的2倍. 相似文献
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移动Ad Hoe网络(MANET)中的路由算法应尽量使网络负载均衡,不均衡不仅导致正在通信的路由由于过度拥塞而引起数据包延时过大、吞吐量下降,而且会使拥塞节点的能量提前耗尽,从而加剧网络拓扑结构的变化及节点之间的不公平性。本文对目前提出的一些负载均衡路由算法进行了简要比较和分析,在此基础上,指出了目前负载均衡路由算法中存在的一些问题,并提出了一个实现负载均衡路由算法的一般模型。基于该模型,文中提出了一种简单的负载均衡路由算法。仿真结果表明,负载均衡路由算法比未考虑负载均衡的路由算法具有更高的数据包投递率和更低的数据包传输延时。 相似文献
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针对航空Ad Hoc网络在高负载下的低时延信道接入问题,提出一种优先级与公平性协作的多信道MAC协议(PBLL/HL)。在多信道检测统计基础上加以改进,结合优先级机制,在高负载网络中适时截流低优先级业务,优化网络流量,保证高优先级业务低时延发送;设计公平性优先级阈值与冲突退避窗口算法(PCA),减小低优先级业务接入时延。仿真结果表明,PBLL/HL能够在高负载网络有效控制信道接入,维持良好的网络流量,降低网络平均接入时延(低优先级业务时延过载时降低10%以上),稳定高负载网络吞吐量(最大吞吐量88.1%,过载时吞吐量下滑平缓),解决了航空数据链高业务量带来的高时延和网络拥塞。 相似文献
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针对无线Ad Hoc网络中表驱动路由算法控制信息的交互模式,提出了“不同网络规模采用不同交互模式”的方法。根据不同的网络规模,采用周期性交互模式或非周期性交互模式实现Ad Hoc网络性能的局部最优。通过理论分析及算法仿真,给出了适合于不同网络规模的控制信息交互模式。仿真结果具有很强的实用性。 相似文献
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Ad hoc网络是一种没有有线基础设施支持的移动网络。本文阐述Ad hoc网络的节点结构,比较了几种典型的网络结构,介绍了Ad hoc网络的特点及移动IP和Ad Hoc网络的结合。并且商场组网的对管理Ad Hoc网络面临的问题进行了一些探讨。 相似文献
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现有的动态频率选择机制有效降低了网络间的干扰,但仅考虑了物理层的干扰最小。
无线局域网网络密度越来越高,支持的业务越来越丰富,不同的业务传输所需要的带宽、允
许的时延均不相同。为了有效提升业务传输效率和网络容量,提出了一种改进的动态频率
选择算法。具体为:接入点将站点的信号接收质量、载干比、占用信道时间系数和业务优先
级作为优化问题的特征参数集,综合考虑多个站点上报的信道测量报告,利用凸优化理论以
吞吐量最优为目标联合进行优化,选定接入点的工作信道。最后,结合实际的场景图,
仿真对比了动态频率选择改进算法和未采用动态频率的性能,结果显示改进算
法使干扰区域的吞吐量增加了10倍,能明显降低WLAN网络的干扰,提升WLAN的业务传输效率
,可广泛应用于WLAN的产品设计。 相似文献
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《中国对外贸易(英文版)》2008,(5):50-51
The overall strategic relationship between U.K. and China is "better than ever", China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future. 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(5)
Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit. 相似文献
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Estaing, former French president, Valery Giscard d'Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself"French Confucian", then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually "Partners". 相似文献
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《中国对外贸易(英文版)》2008,(5):12
The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy. 相似文献
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"If you are considering to trade with companies in Japan or expanding your business to Japan we are ready to help from the very beginning."You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization 《中国对外贸易(英文版)》2008,(10):16-17
If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning." You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization (JETRO). JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China's Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING. 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(12):62-63
Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship, 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(1):10-10
In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country's five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity, 相似文献
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Liu Xinwen 《中国对外贸易(英文版)》2008,(10):40-41
Last November the State Council of China decided to renew its holiday system by reducing the seven-day May Day holiday to three days and introducing three new one-day public holidays, namely the Qingming Festival, Dragon Boat Festival and Moon Festival. By doing so, the three golden-week holidays that were introduced in 1999, namely the Spring Festival, May Day and National Day, could be better distributed. 相似文献
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The results of the Annual Global Public Opinion Survey were released by the British Broadcasting Company 《中国对外贸易(英文版)》2008,(9):40-41
The results of the Annual Global Public Opinion Survey were released by the British Broadcasting Company (BBC) on April 2,2008,the combination of 7,457 public opinion polls in 34 countries,gave Germany and Japan the No.1 and No.2 spots,respectively, while the last four went to North Korea, Pakistan,Israel,Iran. 相似文献
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Nine o'clock in the morning of March th the first meeting of the eleventh session of National People's Congresswas held in the Great Hall of People.As usual the first pefformance ofthis big event in China was from the government working report made by the Premier.Five years of government's WOrk in this session was counted in Premier Wen Jiabao's working report.…… 《中国对外贸易(英文版)》2008,(6):11-11
Nine o'clock in the morning of March 5th,2008,the first meeting of the eleventh session of National People's Congress was held in the Great Hall of People.As usual,the first performance of this big event in China was from the government working report made by the Premier.Five years of government's work in this session was counted in Premier Wen Jiabao's working report. 相似文献