多波束移动卫星系统的自适应开环预编码方法

对于卫星移动通信系统,由于卫星与地面终端之间的相对运动以及星地间传输延迟,传统的基于理想信道信息的预编码方法是不适用的。针对这一问题,提出了一种基于开环信道估计的预编码方法。卫星端利用开环获取的部分信道信息实现多波束联合预编码,并导出了系统传输速率的闭合解析表达式。此外,为了克服强干扰环境下多波束预编码系统性能恶化问题,提出了一种自适应预编码传输方法。卫星发射机依据开环获得的慢时变用户位置信道信息和信道统计量信息,自适应地选择预编码方法或传统频率复用方法,实现最优的系统性能。理论分析和仿真结果表明,与传统的干扰抑制方法相比,所提方法能实现更优的系统性能,同时也克服了传统预编码方法的局限性。     

对移动通信工程组网问题的探讨

目前,第二代移动通信技术及其使用的频谱不能满足发展需求,第三代移动通信是频谱利用率更高、通信容量更大、通信质量更好的移动通信系统。     

基于感知的航空通信系统试飞频率管理

信息技术的快速发展以及频谱用户大增致使无线电频谱成为非常紧缺的资源。航空电子 系统设备量大,功能多,工作频段宽,电磁环境复杂,共址电磁干扰不可避免。科学规划试 飞频率,规避干扰是试飞成功的关键。在分析航空通信系统技术特征的基础上,提出了基于 频谱感知技术的航空通信系统试飞频率管理方法。该方法能够有效提高系统频谱利用率,并 能支持试飞数据相容性分析及重建,提升航空通信系统试飞评估准确性。     

敏捷成像卫星快速需求筹划算法

敏捷成像卫星需求筹划主要解决如何判断敏捷卫星对地观测需求是否可执行以及何时执行的问题。首先，根据敏捷卫星对地观测的约束和特点，将敏捷卫星对地观测场景抽象成基于力学的理想弹簧系统，提出了常量机动时间和劲度系数的计算方法，实现模型关键参数的映射；然后，提出了一种启发式算法，利用理想弹簧系统的平衡状态时对应观测综合角度和最小的特点，通过计算系统的力平衡状态求解多个观测需求的整体最佳观测时间；最后，利用实际的观测需求，通过仿真对比验证了算法的有效性。仿真结果显示，所提算法提高了观测需求满足率和需求的优先级权重和，并且整体成像质量最优。     

基于认知无线电的脉冲陷波UWB窄带干扰抑制

提出了一种基于认知无线电的自适应超宽带（UWB）窄带干扰抑制方法。为了使UWB对变化的 干扰环境具有自适应调节能力,引入了认知无线电技术。通过频谱感知和认知引擎技术提取 窄带干扰频谱特征作为陷波器的设计依据。以高斯脉冲为例,对陷波器的陷波性能进行检验 。最后,就陷波前、后脉冲的通信性能进行比较。仿真结果表明：认知陷波脉冲具有良 好的窄带干扰抑制能力,能够自适应的随着感知结果而动态地规避授权用户,从而实现UWB 系 统与其它通信系统的共存,且此方法不需要在整个频段范围内降低UWB脉冲功率,实现简单 灵活,为提高UWB脉冲发射功率、增大UWB系统的通信距离提供了一种可行的方案。     

基于后验概率的伪码预测研究

卫星通信对抗是电子对抗的一个重要领域，由于卫星链路一般采用扩频技术，传统的干扰方法难以奏效。通过分析伪随机序列的伪随机性，提出了基于后验概率的伪码预测方法。该方法可以根据接收到的伪码计算其后验概率，并以此来预测随后的伪码序列。仿真结果表明，该方法对短码有较好的预测效果。最后，给出了预测方法在瞄准式干扰中的具体应用。     

移动用户目标系统中基于拍卖模型的信道资源分配

为了提高卫星通信信道的频谱利用率,从卫星通信中的认知无线电技术出发,简述了当前认知卫星研究现状。针对移动用户目标系统（Mobile User Objective System,MUOS）的特殊通信环境,提出了插空式（overlay）频谱共享方式下基于拍卖模型的认知卫星信道分配方式,并建立了收益公式。同时,引入星上频谱共享干扰公式来计算认知用户对系统造成的影响,并代入收益公式以计算认知技术给系统带来的收益大小;之后给出模拟通信环境参数,利用Matlab进行仿真计算。仿真结果表明,认知用户的加入虽会使主用户通信质量略有下降,但使系统总体收益呈上升趋势。     

分布式卫星系统的上/下行功率联合控制

为了能合理地控制功率以提高分布式卫星系统的系统效能,研究了其上下行功率联合控制问题。通过分析分布式卫星系统的特征及其功率控制问题的难点,建立了合理的分布式卫星系统功率控制模型和控制方案的具体框架;通过改进现有的上行功率预测和单级调整算法,提出了基于预置、预测和多级调整算法的上下行功率联合控制方法,并给出了控制方法的流程图;最后将所提方法与传统上行控制算法、单级补偿算法和预测算法进行了仿真比较,表明在上下行不同降雨百分比条件下,所提方法能更好地满足功率门限需求;在广州、长春两地不同实测雨衰曲线下,所提方法均能够更准确跟踪雨衰变化;业务与通信网区切换时,所提方法也能快速完成切换和保持动态跟踪,能够较好满足分布式卫星系统的功率控制准确性、时效性等应用需求。     

国外卫星移动通信新进展与发展趋势

在地面移动通信迅猛发展的新形势下,提供相似业务的卫星移动通信的发展动态和趋 势值得关注。首先介绍了国外卫星移动通信市场发展动态,然后分别介绍了静止轨道、中轨 道和低轨道三类卫星移动通信系统的最新进展,其中静止轨道卫星移动通信发展最好,中低 轨道卫星移动通信系统发展相对不景气;最后探讨了卫星移动通信的发展趋势,指出通过星 地集成以及相关技术的不断融合,最终将实现个人通信的终极目标,同时,卫星移动宽带、 终端综合化、星上处理等都是卫星移动业务技术发展的必然趋势。     

遥感影像辅助地图制图的研究和应用

随着社会的进步，人们生活品质的不断提高，对地图系统的内容质量及及时更新有着越来越高的要求，本文结合已有GIS系统和地图数据库，并阐述了传统制图中存在的问题，以及分析了利用卫星遥感资料进行辅助地图制图的过程。     

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.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

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.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

A World of Love 2008 Music Grand Ceremony

Under the guidance of the theme slogan of the 29th Olympic Games - One World One Dream, with dream, love and dedication as its theme, the 2008 Music Grand Ceremony ＆ 1000 People Charity Concert on 100 days cotmtdown to Paralympic Gamesis officiaily launched on December 22, 2007. The 2008 Music Grand Ceremony is sponsored by China Disabled Persons＇ Federation, and co-hosted by National Paralympic Committee of China,     

China''''s National Oil Reserve Center was Born

Aseries of events that occurred in October 2007, are rewriting the history of China's energy industry: November 3 an Energy Law Committee asked the public for suggestions on improvements; forty top experts came together to form the National Energy Expert Advisory Committee on November 6; and the National Oil Reserve Center (NORC)became the nerve centre of oil reserves on November 18. Yet, behind the progress of these recent activities remains the fact that international oil prices still hover around a very high price of US$ 90/barrel, and China's oil imports are close to accounting for half of its total oil reserves.     

MUYANG GROUP

With its headquarters in the historic city of Yangzhou,Jiangsu Muyang Group Co.,Ltd has since its founding in 1967 grown into a well-known group corporation whose activities cover research ＆ development,project design,manufacturing,installation and services in a multitude of industries including feed machinery and engineering,storage engineering,grain machinery and engineering,environmental protection,conveying equipment and automatic control systems.     

2007 China Harbor Ten People

2007 China Harbor Ten People elected the entrepreneurs who contributed a lot to port economy and enterprises this year trough their talent management.These ten people embody their social responsibility,professional skills,creative ability,and charming personality.Bearing full confidence in China＇s port economy,the port entrepreneurs are brave enough to explore a brand new area,so as to promote harbor economic development. At the very beginning of 2008,China Shipping Website,Dalian Maritime University,and China Port and Shipping In- stitute jointly select the 2007 China Harbor Ten People,demonstrate port entrepreneurs＇ stunning minds,disclose their secrets to success,and providing abundant experiences to others in harbor development.The top ten people are various excellence during the ups and downs harbor development.