WCDMA和WLAN向3G和后3G演进

从2G GSM系统到3G WCDMA系统的演进过程中，高速率空中接口技术和核心网反映了两代系统之间的基本变化。随着高速率移动通信系统的发展，基于WCDMA移动通信系统辅助WLAN技术会有利于加快向后3G系统演进步伐。     

3G和4G中的WCDMA和WLAN

本文主要介绍了在3G移动通信系统中使用的WCDMA及其演进技术。本文还介绍了WLAN在移动通信中的应用以及对4G移动通信的一些研究．     

采用WCDMA实现从GSM到3G网络的演进

本文就WCDMA演进的三个阶段进行了探讨和研究,旨在为即将到来的3G网络建设提供建议和参考。     

WCDMA与WLAN融合网络建设研究

随着移动数据业务的迅猛发展,高速率WLAN将会发挥出重要的作用。为此,结合目前联通WCDMA的网络情况,对WCDMA与WLAN网络融合建设进行了分析和讨论,通过分析WLAN与WCDMA网络各类网元的接入、认证、路由等关系来确认建设方案的可行性。     

3G技术演进及WCDMA未来演化

自从20世纪90年代，第一个基于全球移动通信系统（GSM：Global System For Mobile Communications）技术的第二代（2G）数字蜂窝网络出现以来，无线通信市场飞速增长，相应的无线通信技术不断推陈出新，无线通信系统处于一个高速发展完善时期。目前GSM已经成为全球主要的2G无线接入标准，截至2004年2月，全球已有207个国家和地区配置了GSM网络，而GSM客户数已经超过10亿户，占世界移动电话客户总数的72％，     

3G演进工作的进展

1．引言 从2004年开始，3G技术的商用化进程逐渐加快。随着Vodafone于2005年6月3日在新西兰开通WCDMA（UMTS）商用网络，在全球范围内，67个国家共建成了150个3G商用网络，其中有64个WCDMA网络、17个cdma2000 1xEV-DO网络和69个cdma2000 1X网络。与此同时，3G用户也获得了持续增长，截止到2005年4月底，全球范围内共有1．78亿3G用户，WCDMA系统已经发展了2550万用户，cdma2000 1xEV-DO系统也拥有了1290万用户。     

HSDPA--3G的高速化演进步伐

3G的形势日趋明朗．全球已进入了规模商用部署阶段，我国的3G商用也有望在近期展开。但3G技术也受到了其他技术的冲击和挑战，由于IMT-2000标准确立比较早，当时对3G系统的峰速设计为2Mbps，以今天的眼光来看，这一速率已难以满足人们对宽带的期望。近年来WLAN、WiMAX等技术的崛起已对3G形成了挑战．接高达几十兆的传输速率，使无线通信真正向高速领域迈进。对此．3G技术也加快了演进．以应对无线宽带化的需求。     

从无线网侧和核心网探讨2G到3G的技术演进路线

文章就2G到3G演进的技术路线和相关的策略，以GSM／GPRS到WCDMA演进为例进行了详细的探讨。     

WLAN和3G网络的协同构建

随着3G网络技术的迅速发展,WLAN技术与3G网络技术的协同构建是一个热点话题。本篇文章阐述了WLAN的技术概况,并且对WLAN技术的发展进行了分析研究。而后,对WLAN技术与3G网络技术的协同构建发展策略提出了建议和要求。     

国际3G市场演进现状及趋势分析

1 国际3G市场概况截至2003年12月,国际上共有33个国家和地区发放了117张3G牌照,其中WCDMA牌照114张,cdma2000牌照3张(分别是台湾地区的Asia Pacific Broadband Wireless、韩国的LGT和日本的KDDI)。在已经开通的3G网络中,WCDMA网络为12个,它们分别是和记3Denmark、和记3Sweden、和记3Austria、和记3Australia、和记3Italia、和记3UK、和记3HK(2003年6月开通,2004年1月提供服务)、奥地利Mobilkom、NTTDoCoMo、Vodafone K.K.(原J-PHONE)、韩国的SKT和KTF;cdma2000 1xEV-DO网络为4个,分别是SKT和KTF、日本的KDDI、…     

WCDMA and WLAN for 3G and beyond

The WCDMA air interface was initially designed to support a wide variety of services with different QoS requirements having a maximum bit rate of 2 Mb/s. In order to satisfy the future service and application needs several technical enhancements are being studied and standardized for WCDMA in 3GPP. Even with evolved WCDMA, there is a need for another public wireless access solution to cover the demand for data-intensive applications and enable smooth online access to corporate data services in hot spots. This need could be fulfilled by WLAN together with a high-data-rate cellular WCDMA system. WLAN offers an interesting possibility for cellular operators to offer additional capacity and higher bandwidths for end users without sacrificing the capacity of cellular users. The evolved WCDMA air interface will provide better performance and higher bit rates than basic WCDMA, based on first releases of the specifications. Eventually, evolution may not be the answer to all the needs, and come revolutionary concepts need to be considered. However, before some future wireless system can be regarded as belonging to 4G it must possess capabilities that by far exceed those of 3G systems like WCDMA. Judging from an application and services point of view, one distinguishing factor between 3G and 4G will still be the data rate. We could define that 4G should support at least 100 Mb/s peak data rates in full-mobility wide area coverage and 1 Gb/s in low-mobility local area coverage. Other possible characteristics of 4G need to be further studied.     

WLAN与WCDMA融合的解决方案

文章分析了WLAN和3G的特点,介绍了WLAN和WCDMA融合的6种解决方案,讨论了WLAN和3G融合时的认证和计费解决方案,最后简要描述了中兴通讯提供的全系列的WLAN解决方案.     

Multiple Rake Combiners and Performance Improvement in 3G and Beyond WCDMA Systems

We propose an efficient code-assignment scheme utilizing multiple rake combiners to avoid the code-blocking problem in third-generation (3G) and beyond wideband code-division multiple-access (WCDMA) systems based upon orthogonal variable spreading factor (OVSF) channelization codes. The multiple rake combiners are required to be equipped with each base station (BS) and user equipment (UE). The major benefit of the proposed assignment scheme is in handling nonquantized data rates, making internal code fragmentation approximately zero. The task of code assignment to handle quantized data rates is divided into three steps. In the first step, the number of terms satisfying the capacity equation is found. The code combinations for all the terms in step 1 are found in step 2, which can be further subdivided into terms producing unique combinations and multiple combinations of terms. The procedure for finding the optimal code combination according to the number of rake combiners available at the UE and BS is given in step 3. Simulation results show the performance improvement in terms of reduction in blocking probability compared with existing single-code assignment schemes.      

第三代移动通信中的WCDMA技术

简要介绍了第三代移动通信中的WCDMA技术的发展历史、系统结构以及WCDMA中采用的关键技术。     

User-Centric Offloading to WLAN in WLAN/3G Vehicular Networks

In recent years, there has been a growing demand in 3G data services, leading to deteriorating 3G service quality. Noting that Wireless Local Area Networks (WLANs) as well as 3G cellular networks are widely available today, WLANs could be effectively utilized to relieve the overload in the 3G networks. On the other hand, use of IEEE 802.11 WLAN Access Points (APs) has proliferated tremendously, resulting in a communication device inside a mobile vehicle to access the Internet. However, using Internet through APs in moving vehicles is challenging since WLAN APs have a short range and are typically not deployed to cover all roads. Several studies have investigated the performance of using intermittently available WLAN connectivity from moving vehicles for data transfers and predictive offloading in WLAN/3G networks. However, these works have not addressed mobility pattern from the viewpoint that drivers’ mobility is generally known to have a daily routine. Therefore, in this paper, we consider the user’s historical mobility to decide to offload data to WLAN instead of switching to 3G network. The user’s application usage pattern is also considered into predicting available WLANs. To evaluate the performance of our offloading algorithm, we analyze the prediction error and conduct simulations. The simulation results show that the proposed algorithm achieves shorter transmission time than the existing schemes that do not consider user’s mobility pattern by delivering more data to the WLANs.     

3G/WLAN交互网络

3G／WLAN系统的交互，通过无线局域网（WLAN）接入控制功能增加新业务功能，如先进业务支持、实时对等IP通信等；通过引进WLAN和蜂窝IP连接不同类型动态交换；利用多种接入技术和用户内部先进技术来提供不中断业务和可靠安全接入.3G／WLAN是迈向新一代无线移动网络的关键，在系统性能上具有巨大的技术优势，同时也将发挥出巨大的市场潜力。3G通信系统标准组织（3GPP）把3G／WLAN交互系统作为3GPP的附加标准。在移动环境中，3G／WLAN网络双模终端可提供无处不在、带宽可变、服务质量（QoS）可保证的多种高速率业务。     

WLAN与3G之争

目前，IEEE802.11系列的WLAN已成为市场发展的主流，在IEEE802.11标准体系中又分为IEEE802.11b（又称Wi-Fi）、IEEE802.11a、IEEE802.11g，就其应用的广泛性，IEEE802.11b独占鳌头。IEEE802.11b工作于ISM（工业、科技、医疗）的2.4GHz频带，采用补码键控CCK调制方式，支持11Mb/s的传输码率，采用的标准安全协议WEP（WiredEquivalent Privacy）。在中国，中国电信于2002年5月推出了“天翼通”无线宽带局域网，而中国网通于2001年就开始实行“无限伴侣”计划，在上海APEC会议期间，网通的无线局域网已经发挥了巨大的作…     

WCDMA和WLAN的联合建设

本介绍了可能的WLAN同3GPP互联的场景，以及互联中要涉及到的网络结构、网元的功能及网络运行必不可少的漫游、鉴权、计费功能的实现。     

3G与WLAN的网络融合

随着3G移动通信应用业务不断丰富,通信网络的承载能力与大流量高宽带的业务需求之间的矛盾日益增加。3G技术难以支撑大量的数据用户的多媒体应用的需求。WLAN作为具有高性价比和大规模部署能力的无线数据技术,可以很好地卸载3G的压力。所以3G＋WLAN互为补充的发展战略成为运营商的共同选择。本文回顾了多种3G和WLAN相结合...     

WCDMA 备受青睐的3G标准

1.未来移动网络需要宽带技术与现有技术相比,采用WCDMA将大大降低移动业务的成本,视频流或音乐下载就是很好的例子。虽然基于现在的2G/2.5G移动网络平台就可以提供这些业务,但只有宽带移动网络才能使该类业务的成本降低到大众化普及水平。网络负荷能力对提供实时性业务十分关键,因为这最终影响到成本和用户体验。如果有1万用户都需要即刻更新某项信息,比如体育赛事或财经消息,所形成的峰值负荷需求意味着运营商要为应对这种情况而扩大网络规模。如果没有宽带技术,仅此一点就要大幅度增加成本。这就是移动网络需要WCDMA的原因之一。WCD…