面向新一代移动通信的智能天线技术

第三代移动通信系统,最重要的技术特征将是智能移动通信技术,即系统的各功能模块将由智能化处理单元来实现,作为智能化处理单元重要组成部分的智能天线,其在新一代移动通信系统中的开发和应用研究已成为当今移动通信界的热点。本文就其技术思想、研究成果及现有水平进行了讨论,并就其进一步的发展进行了简要论述。     

GEO多波束卫星移动通信系统多址方式选择的研究

简要介绍了卫星移动通信系统的发展及分类,对影响静止轨道（GEO）卫星通信系统用户共享有限通信资源和有效利用卫星链路资源的多址接入方式进行了分析。主要从有效容量、实际应用和具体实现角度考虑分析比较,得到在GEO卫星通信系统中采用TDMA多址方式优于CDMA多址方式的结论。最后探讨了我国GEO卫星移动通信系统的现状和发展方向。     

中国通信市场的发展现状与投资趋势

本文首先介绍了2000年中国通信市场的情况，然后从电话交换、接入网、光通信网络、移动通信、数据通信和因特网这六个方面预测了2001年中国通信市场的发展趋势，并指出未来5年内中国通讯市场的发展主要集中在移动通信、数据通信和因特网相关联的通信业务方面。     

空间激光通信中的光学系统

给出了空间激光通信系统中光学系统的构成并分析了各个部分的功能,介绍了几种形式的光学天线及空间激光通信中的自适应光学技术。在光学天线的分析中,指出卡塞格伦天线用于空间激光通信所具有的优势,分析了卡塞格伦天线的性能以及设计中要注意的问题。     

Handover mechanism and speed considerations in personal communication systems

In this paper, we discuss views concerning different approaches to the analysis of personal communication systems (PCSs): an outside observer's point of view, a user's point of view, and a base station's point of view. In these three approaches the paper focuses on the handover mechanism rather than on the data traffic modeling. In particular, we reexamine these different methods of analysis, combine these views with our approach, and propose a new queueing model. We take into account the speed factor and show that the ordinary measurements that are based on the state probabilities are not appropriate. In addition, we propose a layered queueing model in which low-speed and high-speed users are treated differently.     

新千年通信发展趋势估测

首先对迄今的通信过程作简单回顾，然后详细说明Ｉｎｔｅｒｎｅｔ如何促使数据通信业务量飞跃增长，超过传统电话通信，从而提出对未来国家通信网方向的构思，阐述光纤通信如何推动大容量宽带通信网的形成和无线移动通信如何促使全球个人通信的实现，最后，对新千年通信发展趋势的估计提出几点意见。     

无线光通信宽带接入技术及其应用

随着“光纤接入的最后一公里”问题,无线光通信技术应运而生了。本文介绍了无线光通信技术的基本概念,阐述了其优缺点,介绍了目前较先进的无线光通信领域的关键技术及其应用场合,并对实际无线光通信系统的发展方向进行了展望。     

智能天线应用于卫星移动通信终端抗干扰

智能天线技术可以极大地增强卫星通信系统的抗干扰性能。讨论应用于卫星移动通信终端的智能天线技术,提出了利用智能天线技术的卫星移动通信终端的两种可能的系统实现方案。从计算成本及干扰抑制性能的角度对它们做了初步的比较,仿真结果表明采用这两种实现方案的卫星移动通信终端可以有效抑制下行链路存在的干扰,提高输出信干噪比,取得较为满意的干扰抑制效果。     

现代移动通信信息安全技术研究

随着移动通信和计算机技术迅猛发展,移动通信用户人数也在呈现爆发式的增长,移动通信产业市场潜力发展特别巨大,随之而来的人们对移动通信提出了更高的要求。回顾移动通信技术经历了由1G到4G的发展,通话和数字传输功能得到巨大的提高和完善,但是4G系统LTE/LTE-A网络的安全问题却经常被提出,本文就对LTE中的体系结构、访问机制、切换过程中的安全问题进行了研究。     

A combined optical–wireless indoor communication system

This new combined optical–wireless indoor communication system provides an economic and flexible approach for local area networks mainly in large buildings or in a group of several buildings. The radiation from the radio base stations of mobile networks cannot penetrate into large buildings completely. That problem is more serious at higher frequencies. The present approach offers a good solution to this problem. In this approach the wireless communication serves small picocells which are interconnected by an optical backbone. The performance of the system is enhanced by assigning a specific radio frequency for each picocell which enables the transmission of the wireless channels without altering their modulation formats. This method allows for a simple, and low-cost indoor communication system.     

2004年全球移动通信市场回顾

2004年是全球电信市场回暖的一年,移动通过市场的各个领域都有了很好的发展,在移动通信系统方面,移动通信网络建设和技术发展都进入了快车道,在移动通信业务方面,一按即通（PTT）业务,以及移动电视业务成为了运营商关注的焦点。在移动通信设备领域,3G终端问题得到缓解,3G系统快速发展起来。此外,移动号码可携带政策在2004年也得以实施。从移动通信系统发展、移动通信业务、通信设备、通信管制政策等方面总结2004年的移动通信发展情况。     

向第四代移动通信系统演进

首先简要介绍移动通信发展的历史和第三代移动通信系统的特点,然后重点介绍第四代移动通信系统的出现和关键技术,最后对第四代移动通信系统作了展望。     

5G移动网络绿色通信的相关关键技术

5G移动网络绿色通信技术相对于4G技术来说,在网络速度、网络延时和网络容量上进行了不断的提升。随着我国智能化的设备不断发展,5G移动网络绿色通信技术所面向了全社会的网络。由此可以预见,在未来人们的数据传输将变得更加高速率和高性能。本文在研究的过程中,主要结合第5代移动通信系统的具体建设和关键技术,分析当前我国第5代移动通信系统能耗问题,同时对于5G绿色通信技术的关键问题进行必要的分析。     

Power control with coder-estimator sequences

Power control is an important issue in mobile communication systems and has been studied extensively in the literature. This paper has taken on a new perspective and modeled the problem as a state estimation problem with finite communication constraints. The problem is solved by using the 1-bit mean coder-estimator sequence. The performance of the coder-estimator sequence is compared with that of the simple feedback power control technique by evaluating their respective fade margins as in commonly done in radio system engineering.     

基于自由空间光通信技术的研究

自由空间光通信（FSO）是以大气为传输媒介,以激光的波长作为载体用以携带高速信息的无线传输技术,它是光通信与无线通信的结合,并兼有光纤通信的高速传输与无线通信可灵活移动等优点,无须挖沟,无须申请频率许可证,为当今卫星通信技术的首选。关键技术主要对FSO通信系统中接收灵敏度进行分析以及对接收的光学系统中跟踪原理进行剖析,为进一步提高自由空间光通信的性能作铺垫。     

移动通信电源系统可靠性提升策略

随着移动通信技术的快速发展,移动通信电源的功能也得到了不断的创新和完善,当前的移动通信电源系统已经具备了较好的安全性和稳定性,但随着移动通信用户要求的不断提高,和移动通信业务的快速发展,移动通信电源系统的可靠性得到了更为广泛的重视,如何通过技术手段或管理手段实现移动通信电源系统可靠性的提升,已经成为广大技术人员所关注的重要课题。本文在介绍移通信电源系统构成的基础上,对其可靠性的内涵进行了阐述,并就如何通过合理的技术与管理手段来提升移动通信电源系统可靠性提出了一些可行的方法,以供参考。     

Half‐duplex visible light communication using an LED as both a transmitter and a receiver

In typical visible light communication (VLC) systems, light‐emitting diodes (LEDs) are used as optical transmitters and photodiodes are used as optical receivers. Currently, many communication devices such as smart phones have a built‐in LED lamp whereas they usually do not have a built‐in photodiode. If we find a way to receive VLC signals without the need to add an additional photodiode on the communication devices, it will contribute to the spread of VLC. Therefore, we propose and demonstrate a VLC scheme without the need for a photodiode. As the first step, we investigate the characteristics of an LED as a VLC receiver and find out that an LED can also be used as a VLC receiver in certain conditions. Then, we demonstrate a half‐duplex VLC system using an LED as both an optical transmitter and an optical receiver, without the need for a photodiode. This technique could be used in various applications such as the VLC between smart phones with a built‐in LED lamp and the VLC between LED traffic lights. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluation of light beams for short and medium range wireless communications

Technological improvements in free space optical communication systems have reduced the cost and alternatives to fiber optic transmission. The advantages of the free space optical link over fiber optic cabling are primarily economic. In line with the demand for gigabyte link from 10 Mbit/s to 10 Gbit/s in the market, the uses of free space optical communication systems have increased exponentially from 1995 to 2008. However, free space optics is subject to atmospheric effects such as attenuation and scintillation which can reduce link availability and may introduce errors not seen in fiber transmission. In this paper we argue that optical wireless communication is an alternative to fiber optic transmission in short and medium range wireless communications and we discuss that the liability and availability of the free space optical link is mainly determined by the local atmospheric condition, this is to say that the transmission quality may be affected by weather conditions. For the evaluation we constructed an experimental communication network with a free space system. One way to characterize the strength of the turbulence fluctuation is by examining the Rytov variance for a plane wave. This Rytov variance physically represents the intensity fluctuation induced by atmospheric turbulence.     

2.3km、1.25Gb/s空间移动平台激光通信实验

介绍了一套基于空间移动平台的完全脱离PC机的高实时的无线激光通信演示系统,用通信终端的相对运动来模拟实际卫星间的相对运动.实验实现了2.3km距离、1.25Gb/s速率的自由空间移动平台光通信,通信系统主要分为APT和通信两大部分.实验很好地实现了移动平台间的光通信,达到了设计要求.     

移动通信系统的演变

介绍了移动通信系统的发展历程以及各个阶段移动通信系统的特点．就系统参数、体系结构、应用范围等进行了分析．并对未来移动通信的发展方向做了展望。