4G中的关键技术及其与3G的比较

本内容涉及了第四代移动通信中的关键技术，并对它的技术优势、特点与第三代移动通信技术的相关方面做了论述。     

3G业务演进与未来移动通信发展趋势

本文基于对不同网络环境下业务体验、3G业务能力和业务进展的分析比较，从业务演进角度探讨并具体分析了未来移动通信发展的内容多媒体化、业务个性化、承载IP化、接入综合化、终端智能化的发展趋势。     

后3G移动通信研究综述

未来人们对移动多媒体业务的巨大需求是后3G研发的主要动力。WCDMA演进的方向有两个:高速下行链路分组数据接入(HSD-PA)和业务协调。在走向4G之前,欧洲提出了一种旨在提供宽带传输能力的过渡系统———移动宽带系统(MBS),其最高速率可达150Mbit/s。从现在来看,对后3G系统总的要求包括:强大的多媒体业务处理能力、先进的移动性管理、支持多种无线接入、提供无缝服务和应用服务支持等。     

移动通信3G技术概述

简介 中国移动与中国联通在移动通信市场的竞争日趋激烈,竞争领域从原先的话音业务发展到增值业务.伴随着移动增值业务的不断发展,迈向3G(3rd Generation,第三代移动通信)则是两大移动运营商的必然选择.与前两代系统相比,第三代移动通信系统的主要特征是可提供丰富多彩的移动多媒体业务,其传输速率在高速移动环境中支持144kb/s,步行慢速移动环境中支持384kb/s,静止状态下支持2Mb/s.其设计目标是为了提供比第二代系统更大的系统容量、更好的通信质量,而且要能在全球范围内更好地实现无缝漫游及为用户提供包括话音、数据及多媒体等在内的多种业务,同时也要考虑与已有第二代系统的良好兼容性.     

谈谈第三代移动通信3G

文章详细介绍了第三代移动通信概念的提出、技术标准、频段的划分及其发展的时间表 ,并着重就ITU R对第三代移动通信中的无线接口标准所做工作和我国对第三代移动通信的贡献作了详细阐述 ,并提出了作者对我国发展第三代移动通信的一些看法。     

3G移动通信市场的管制问题探讨

1 目前我国2G移动通信管制中存在的问题 1．1 不均衡的市场格局 从市场结构看,目前我国移动市场只有两家移动运营 商,其中,中国移动占据了近75％的市场价值份额和66％ 的用户市场份额,拥有很强的市场主导能力,因此,它与联 通并非势均力敌,所以并不是双寡头格局。突出表现在市场     

3G的市场前景

3G是时下业界和传媒普遍关注的热门话题。作为第三代移动通信的3G，是包括标准的制定、系统网络、终端应用开发等在内的一个整体概念，其鲜明特点是高速度、多媒体、个性化。其广泛的用途和诱人的前景，使得3G一经产生便骤然升温，然而好景不长，被热炒的3G如今已遭遇寒流，全球各地3G牌照价格一跌再跌，芬兰电信更首开先河，把买来的3G牌照又退还给挪威政府；欧洲最大的移动网络运营商沃达丰将3G互联网服务推迟到2003年；阿尔卡特、飞利浦、爱立信等手机厂商正急于从3G业务中抽身而走；诺基亚的股票更是缩水75%；日本的最大手机商NTT…     

3G无线网络规划

众所周知 ,无线资源是３Ｇ网络中最为宝贵的资源 ,而无线系统投资在整个３Ｇ网络投资中也占据了相当大的比例 ,因此如何尽量提高频谱效率、充分利用无线网络设施向尽量多的用户提供高性能的接入服务就成了运营商最为关心的一个问题。除了设备和技术水平的因素外 ,无线网络规划也是其中非常重要的一环 ,它将直接影响到网络性能和建设成本。由于设计方法和经验的问题也经常导致网络实际部署后达不到原定的设计要求。１３Ｇ无线规划特点由于ＣＤＭＡ技术具有较高的频谱利用效率 ,目前几种主要３Ｇ技术均基于ＣＤＭＡ接入方式。与传统的时分多址…     

Packaging of optoelectronic and RF components with shared elements for dual-mode wireless communications

The development of a new hybrid packaging method is reported, where the front end radio frequency (RF) element, namely a modified quasi-Yagi antenna, is integrated with an optical transmitter and an optical receiver on single PCB for dual-mode, i.e. RF/free space optical communication. The VCSEL and the pin diode are placed on the antenna directors to share the common metal pads on the Duroid (RT 6010) board. The modules have demonstrated dual-mode wireless communication capability, i.e. RF and free space optics. Though the RF channel induces noise to the optical transmitter/receiver due to electromagnetic coupling between closely-spaced RF and optical circuits, a data rate of 2.5 Gbit/s is demonstrated for the optical channel.     

3G wireless communications for mobile robotic tele-ultrasonography systems

Mobile healthcare (m-health) is a new paradigm that brings together the evolution of emerging wireless communications and network technologies with the concept of 'connected healthcare' anytime and anywhere. In this article, we present the performance analysis of an end-to-end mobile tele-echography using an ultra-light robot (OTELO), over the third-generation (3G) mobile communications network. The experimental setup of the OTELO system over a 3G connectivity link used to measure the system performance is described. The performance of the relevant medical data and the relevant quality of service (QoS) issues defined in terms of the average throughput, delta-time packet delay, and jitter delay are investigated. The real-time 3G performance results show the successful operation of this bandwidth demanding robotic m-health system.     

RF/wireless interconnect for inter- and intra-chip communications

Recent studies showed that conventional approaches being used to solve problems imposed by hard-wired metal interconnects will eventually encounter fundamental limits and may impede the advance of future ultralarge-scale integrated circuits (ULSls). To surpass these fundamental limits, we introduce a novel RF/wireless interconnect concept for future inter- and intra-ULSI communications. Unlike the traditional “passive” metal interconnect, the “active” RF/wireless interconnect is based on low loss and dispersion-free microwave signal transmission, near-field capacitive coupling, and modem multiple-access algorithms. In this paper we address issues relevant to the signal channeling of the RF/wireless interconnect and discuss its advantages in speed, signal integrity, and channel reconfiguration. The electronic overhead required in the RF/wireless-interconnect system and its compatibility with the future ULSI and MCM (multi-chip-module) will be discussed as well     

Device technologies for RF front-end circuits in next-generation wireless communications

Next-generation high data rate wireless communication systems offer completely new ways to access information and services. To provide higher data speed and data bandwidth, RF transceivers in next-generation communications are expected to offer higher RF performance in both transmitting and receiving circuitry to meet quality of service. The semiconductor device technologies chosen will depend greatly on the tradeoffs between manufacturing cost and circuit performance requirements, as well as on variations in system architecture. It is hard to find a single semiconductor device technology that offers a total solution to RF transceiver building blocks in terms of system-on-chip integration. The choices of device technologies for each constituent component are important and complicated issues. We review the general performance requirement of key components for RF transceivers for next-generation wireless communications. State-of-the-art high-speed transistor technologies are presented to assess the capabilities and limitations of each technology in the arena of high data rate wireless communications. The pros and cons of each technology are presented and the feasible semiconductor device technologies for next-generation RF transceivers can be chosen upon the discretion of system integrators.     

用于3G和蓝牙系统的射频设计软件

介绍一款用于3G的蓝牙系统和射频设计软件。     

Space-time block-coded OFDM systems with RF beamformers for high-speed indoor wireless communications

A beamforming network is considered for a space-time block-coded orthogonal frequency-division multiplexing system in a high-speed indoor wireless network. We find that choosing the most powerful beams for transmission provide the best performance in the absence of interference. In the presence of interference, an iterative two-metric beam-selection method is proposed.     

宽带无线通信射频收发前端设计

介绍了一种宽带无线通信系统(BWCS)。提出了一种应用于该系统TDD模式射频(RF)子系统设计方案,并对RF子系统进行了分析。研制出射频子系统电路,给出了测试结果。测试结果表明研制的RF子系统各项指标都满足宽带通信系统的设计要求。     

新型无线移动通信用物理发泡绝缘同轴射频电缆

介绍了CMRC公司设计制造的无线移动通信系统用物理发泡绝缘同轴射频电缆。这种电缆具有低损耗、低驻波、良好阻抗稳定性等优良性能。电缆优良的性能足以用于模拟或数字蜂窝状设备，以及广播、微波、陆地移动无线电、军用等领域。