改进的基于合作博弈的资源分配和接入控制策略

为了提高频谱共享的有效性和公平性,提出了一个基于合作博弈的认知网络频谱共享 模型和接入控制策略。博弈规则为在满足各用户最小收益的前提下,认知用户进行相互合作 ,并最大化总体收益;接入控制策略以满足服务质量需求为约束条件,并引入惩罚函数,迫 使认知用户按照其实际需求竞争频谱资源。仿真结果表明：提出的合作博弈模型和接入策略 提高了认知用户的总体收益和公平性,改善了系统中认知用户的满意度。     

一种基于CoMP的随机接入方案

提出了一种新的基于协作多点传输和接收（CoMP）技术的多发随机接入流程,并根据 随机接入的目的和业务类型设计了接入优先级,在此基础上设计了一种新的随机接入方案, 对 不同类型的随机接入请求提供不同的接入机制,以保证边缘用户的接入性能和满足不同业务 的QoS需求。仿真结果表明,与LTE标准随机接入方案相比,该方案对系统整体接入性能略有 提高,且大大提高了边缘高优先级用户的接入性能。     

认知无线电频谱合作检测技术

认知无线电通过灵活地感知环境的变化,探测暂时末被使用的频谱孔,为未授权用户提供接入机会,大大地提高了频谱利用率,被认为是当前解决频带使用拥挤的最佳方案。频谱检测是认知无线电中极其重要的环节,目前频谱检测技术的研究主要包括两方面:非合作检测和合作检测。本文重点介绍认知无线电频谱检测的合作检测方式、系统模型、监测协议、检测机理及常用的检测算法等,并总结了目前频谱检测技术中有待解决的一些关键问题和技术。     

基于比例速率保证的信道误差OFDMA中继系统资源分配

针对存在有信道估计误差的正交频分多址（OFDMA)中继系统,在考虑用户传输中断概率的同时,提出了满足不同用户最小服务质量（QoS）需求和比例公平性约束条件下的中继选择、子载波分配和功率分配的联合优化问题,建立了以最大化系统总容量为目标的优化模型。在此基础上以速率最大化为目标进行最佳中继选择,并通过动态子载波分配来满足用户的最小QoS需求和比例公平性,最后采用拉格朗日乘子法来得到最优功率分配方案。仿真结果表明,此算法在降低用户中断概率的同时,提高了系统吞吐量并保证了用户速率的比例公平性。     

采用TDMA和CSMA混合MAC协议的时隙调整算法

由于车联网(VANET)拓扑动态变化,车辆高速移动以及不同服务质量要求,制定媒体接入控制(MAC)协议面临巨大挑战。在控制信道间隔内采用基于TDMA和CSMA的混合接入协议是最有效的MAC协议之一。基于TDMA和CSMA的混合MAC协议(T-C-MAC)能够依据车辆环境调整TDMA帧长度,并能有效地传输非安全消息。为了提高T-C-MAC协议的性能,提出了一种基于三跳邻居信息的时隙调整(THSA) 算法。通过有效地调整车辆传输时隙,基于THSA的MAC（THSA-MAC）协议能够有效地实施广播服务,提高了安全消息传输率。实验数据表明,THSA-MAC有效地提高了安全消息传递率。     

主用户活跃性下的多功率分配策略

考虑到认知用户在信息传输过程中主用户的状态可能随时变化,提出了一种新的功率分配模式——多功率分配策略。在基于频谱感知的系统模型中,以认知系统的吞吐量为目标函数,得出了主用户感知过程的多种状态,并分配三种不同的功率,最大化认知系统的容量。仿真结果表明,随着主用户活跃指数的逐渐提高,所提新模型的功率分配策略要优于传统方法。同时分析了新的功率分配下平均干扰功率与主用户接收端的信噪比对系统吞吐量和最优感知时间的影响,进一步验证了所提出新策略的有效性。 〖HT5H〗关键词：〖HT5K〗认知无线电;主用户活跃;频谱感知分配;多功率分配;吞吐量最大化     

基于寡头定价的动态频谱接入控制

为了解决频谱接入中主用户和次级用户交互信息过程复杂的问题,提出了一种基于寡头定价的动态频谱接入控制算法。该算法利用博弈论建立寡头定价模型,通过控制次级用户的频谱接入过程以实现系统收益的最大化,算法只需一次用户信息交互,且无需建立公共控制信道,网络拓扑结构简单。通过比较帕累托最优与全局最优的关系,实验计算与性能分析证明了该算法的有效性。     

空间复用认知无线电系统信道选择优化

在异构认知网络中,认知用户相对于主用户空间位置的不同可能提供空间复用的频谱接入机会,且空间复用的机会受限于干扰容限。首先引入用户空间位置干扰图,度量干扰和评估空间复用机会,在此基础上讨论了基于空间复用的系统吞吐量优化问题,并借助博弈论求解一组最优信道选择集合,主要工作是证明了该博弈问题是至少具有一个纯策略纳什均衡的精确势能博弈,且纳什均衡点是上述优化问题的最优解。最后,数值仿真验证了理论分析的正确性,同时证明考虑认知用户位置带来的空间复用后,系统吞吐量显著增加,有效提高了频谱利用率。     

校园网无感知认证安全研究

随着高校信息化的不断发展,校园网络管理员的工作日益繁重,校园网安全显得越来越重要。为简化用户的网络接入认证过程,确保用户登录安全,提出一种基于DHCP与无感知认证相结合的网络安全接入方案。该方法首先依据MAC地址作为用户接入网络的安全标志,以Portal认证方式接入校园网,结合DHCP协议,对认证方式进行改进和二次验证,从理论上论证了方案的可行性。最后通过实际实验的模拟验证,验证了该方法的可行性,实现了用户的无感知安全认证,提高了校园网的安全性。     

一种贪婪的异构多信道并行合作频谱感知方法

为了同时对多个异构信道进行有效地合作频谱感知,并克服现有方法中只考虑检测准确性而忽略感知开销和系统效益,忽略不同认知用户对不同异构信道感知性能的差异以及参与合作感知的认知用户较多等问题,提出了一种贪婪的异构多信道并行合作频谱感知方法。根据对感知开销和传输收益的定义,充分考虑不同认知用户对不同异构信道感知性能的差异,利用贪婪算法在多个认知用户和多个异构信道间最优地进行感知任务分配,使总系统效益最大。仿真结果表明,所提方法与基于迭代匈牙利的并行合作频谱感知方法、改进的基于迭代匈牙利的并行合作频谱感知方法和随机的合作频谱感知方法相比,能够获得较高的总系统效益,且所需的参加合作感知的认知用户数较少。     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Belarus, A Chinese Fort in Europe

＂In recent years, we＇ve found increasing interest from Chinese investors in the Belarus economy. Please let China know, Belarus is always ready to be a true friend to China. We have built a fort in Europe for China,＂ the President of Belarus, Alexander Lukashenko told Zhou Xiaochuan, President of the Bank of China, during his visit to the capital of Minsk, on January 8th, he expressed his high praise and firm confidence in the development of Sino-Belarusian relations.     

What＇s Behind Spring Festival？

Similar to what the Christmas Day means for the westerners,the Spring Festival is the most important celebration for Chinese people.This big event according to Chinese traditional lunar calendar relaxes and pleases the whole country as the happiest gathering time of the year.National-wide crusade for going back home,too-difficult-to-get train tickets,generous family-going-out shopping,Miaohui laundering,New Year Eve reunion dinner,visiting friends and relatives,watching annual TV gala......each piece of clue reminds us of the smell of Chinese Spring Festival.     

KEY WDRDS for Foreign Investment in China

FDI(Foreign Direct Investment),a component of a country's national financlal accounts,is investment of foreign assets into domestic structures,equipment,and organizations.It does not include foreign investment into the stock markets,concession and subcontract.FDI iS thought to be more useful to a country than investments in the equity of its companies because equity investments are potentially "hot money"which can leave at the first sign of trouble,whereas FDI is durable and generally useful whether things go well or badly.     

Universal Coverage, Pinpoint Illustration and Profound Impact HTC 2008 Intermedia Recommendation and Introduction Meeting

Holding 88 percent of train media resources across China, based on "Time Cube", on the 2008 Intermedia Recommendation and Introduction Meeting on December 19, 2007, HTC announced its high-profile strategy of tour marketing and tapping the immeasurable potentials on the train. Meanwhile, HTC officially launched its brand new product Olympic Train on the meeting, providing a fabulous platform for all the brands that are prepared to do a smart marketing on the occasion of 2008 Olympic Games.     

Market presence in China strengthened Network growth and Dual-Chinese-Hub Strategy More frequet Flyer Benefit——Air China and shanhai Airlines Join Star Alliance

In the end of 2007, Air China Limited (hereinafter "Air China") and Shanghai Airlines, formally joined Star Alliance at a ceremony held in the new Terminal Three at Beijing Capital International Airport. With the addition of the two Chinese airlines, Star Alliance now has 19 member carriers operating 17,000 daily flights to 897 destinations in 160 countries.     

Brown＇s Blossom in Britain-China

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.