宽带无线城域网中的关键技术

无线城域网(WMAN)技术是继无线局域网(WIAN)之后出现的又一项宽带无线接入技术，它的推出是为了满足日益增长的宽带无线接入(BWA)市场需求。虽然多年来WLAN技术及其他很多专有技术被用于BWA，并获得了很大的成功，但是WLAN的整体设计并不能很好的适用于室外BWA的情况，当其用于室外时，在带宽和用户数方面将受到限制，同时还存在着通信距离等其他一些问题。基于上述情况。     

基于WiMAX技术的宽带WMAN及其应用

随着计算机和无线通信技术的迅猛发展,尤其是考虑到用户对高速业务、终端移动与漫游的强烈需求,信息网络的基础设施正在快速向无线联接、无缝覆盖的目标迈进。其中,蜂窝移动通信系统和无线局域网(WLAN,Wireless Local Area Networks)的极大成功,促使人们将目光转向传统的城域网领域;而伴随着骨干网向IP宽带化的发展和用户数据业务的快速增长,     

基于WLAN的宽带无线多接入解决方案

数据业务已越来越多地步人移动领域，手机体积的日趋缩小、数据处理能力的日趋提高以及3G无线广域网(WAN)的广泛部署均人大提高了数据业务的便捷性与可用性。图1显小了移动通信的演进模式。尢线局域网(WLAN)和蓝牙技术等补充技术也进一步增强了数据业务的接入与交付能力。在当今多种接人技术(multi—access)共存的时代，用户希望在多个接入连接上得到连续、优化的作业连接(service-session)。此外，用户还希望能够获得定制服务，这标志着“始终最佳连接(ABC)”时代的来临。     

宽带无线接入的应用与发展

你想体验无线上网冲浪的快感么?你知道宽带无线接人标准有哪些?你想了解宽带无线接人在中国的发展前景吗?本期专家将为你详细介绍。     

宽带无线接入技术概述

宽带无线接入技术代表了宽带接入技术一种新的发展趋势，不但建网开通快、维护简单、用户较密时成本低，而且改变了本地电信业务的传统观念，最适于新的电信竞争者开展有效的竞争。宽带无线接入技术一般包含无线个人域网(WPAN)、无线局域网(WIAN)、无线城域网(WMAN)、无线广域网(WWAN)四个大类，它们共同组成宽带无线接入的网络架构。     

WiMAX无线宽带技术对3G的影响

WiMAX的全称为world interoperability for microwave eaccess,即全球微波接入互操作性,又称IEEE 802．16a标准。WiMAX的目标是帮助推动和认证采用IEEE 802．16和欧洲电信标准化协议(ETSI)HiperMAN无线城域网规范的宽带无线产品的兼容性和互操作性,其任务是加快符合IEEE 802．16技术标准的无线宽带设备的上市速度,加速全球最后一公里的宽带部署。     

无线局域网与3G之争

本文介绍了无线局域网和第三代移动通信技术，通过对两者优缺点的比较，提出了将两者快速融合以适应竞争的观点。     

WLAN＋WiMAX=全方位宽带无线

WLAN：无线局域网的宠儿 WLAN即无线局域网，结合了无线通信技术和计算机网络的优势，以无线信道为传输介质，实现在短距离内的无线网络通信。无线局域网的基础还是传统的有线局域网，它只是在有线局域网的基础上通过无线访问点(AP)、无线网桥、无线网卡等设备使无线通信得以实现。     

3．5G宽带无线接入系统应用探讨

本文从不同角度对3．5G宽带无线接入系统的应用模式及存在的问题进行了分析探讨。     

GPRS+WLAN:一种全新的移动数据业务

GPRS和WLAN是当前流行的两种无线数据接入技术。本文从两者的技术特点出发，概述了几种结合两者特点的新型移动数据接入方案，并在此基础上给出了一种全新的GPRS＋WLAN的移动数据业务，该业务将有广阔的市场前景。     

3G和WLAN集成网络中的QoS的研究

将WLAN和3G结合,已经成为一种趋势.因此,需要考虑WLAN和3G结合的QoS问题.在这篇论文中,主要研究了将3G和802.11e相结合,为WLAN和3G集成网络的用户提供端到端的QoS业务.通过仿真,研究了WLAN误码率对3G业务类别传输吞吐量的影响.     

3G网络与WLAN协同规划之探讨

分析了WLAN的技术特点、承载能力、应用场景;探讨了3G网络如何与WLAN协同规划;指出WLAN可作为3G网络的有效补充,和业主充分合作,在公共热点区域建设WLAN,以分流3G网络的高速数据流量,提升3G网络质量,改善用户体验;最后就如何充分发挥WLAN的作用提出了建议。     

四网协同场景下的核心网互操作方案

本文以四网协同组网场景下的互操作方案为切入点,通过核心网的深度融合,从实际业务连续性保障的需求出发,探讨分析了终端在2G/3G/LTE和WLAN之间的无缝漫游及互操作流程,实现业务连续性体验,往四网协同发展的目标演进.     

An Integrated AP for Seamless Interworking of Existing WMAN and WLAN Standards

Broadband Fixed Wireless Access (BFWA) systems represent a potential technological foundation for the Fourth Generation of Wireless Mobile Communication Systems (4G) as they can replace wired broadband and, with sufficient widespreading deployment, can significantly cut into the usage of cellular networks in many areas. In this context, the seamless interworking of Wireless Metropolitan Area Network (WMAN) and Wireless Local Area Network (WLAN) technologies is an efficient solution to provide the indoor extension of BFWA systems coverage, which would largely contribute to their success and penetration in the market. In this paper, we introduce a novel Access Point (AP), called WMAN/WLAN AP (WWAP), which essentially integrates in a compact device a WMAN Subscriber Station (SS) and a WLAN AP in order to extend the WMAN coverage in-house and to guarantee the end-to-end Quality of Service (QoS). Besides the technical features, the market trends and the usage scenarios where the WWAP might be a cost-effective and a very efficient solution are outlined. Finally, simulation results are carried out in order to demonstrate the effectiveness of the proposed AP. Simone Frattasi was born in Rome, Italy, on December 13, 1977. He received his B.Sc. and M.Sc. degrees from the University of Rome Tor Vergata, Italy, in 2001 and 2002, respectively. He has been employed by the University of Aalborg, Denmark, in the Wireless Networking Group (WING) as Research engineer (2002–2004), working on the IST-STRIKE (Spectrally Efficient Fixed Wireless Network based on Dual Standards) and VeRT (Vehicular Remote Tolling) projects. He is currently a Ph.D. student in the Center for TeleInFrastruktur (CTIF), Aalborg University, working on the JADE (Joint Advanced Development Enabling 4G) project, a joint cooperation of CTIF and SAMSUNG. His research interests mainly concern the Fourth Generation of Wireless Mobile Communication Systems (4G), in particular, heterogeneous services and architectures, clustering algorithms and MAC protocols related to the issues of cooperation and relaying in cellular extended short-range communication systems, hybrid and cooperative location techniques, QoS and ARQ/HARQ. Ernestina Cianca graduated cum laude in Electronics Engineering in 1997 at the University of L'Aquila. She was Italtel/Siemens (L'Aquila) from 1997 to 1998. She got her Ph.D. degree from the University of Rome Tor Vergata (URTV). The thesis work was on power management in CDMA-based satellite systems. She has been employed by the University of Aalborg, Denmark, in the Wireless Networking Group (WING), as Research engineer (2000–2001) and as Assistant Professor (2001–2003). She is currently Assistant Professor in Telecommunications at the URTV (Department of Electronics Engineering), teaching DSP, Information and Coding. Her research mainly concerns wireless access technologies (CDMA and MIMO-OFDM-based systems), in particular, Radio Resource Management at PHY/MAC layer, ARQ/HARQ, TCP-IP issues over wireless links, integration of terrestrial and satellite systems. She has been the vice-coordinator of the following national research programs: CABIS, on CDMA integrated mobile systems (2000–2002) and SHINES, on satellite-HAP integrated networks for multimedia applications co-financed by MIUR (2002–2004). She is currently working on various European Projects. She is author of about 40 papers, on international journals/transactions and proceedings of international conferences. Ramjee Prasad was born in Babhnaur (Gaya), Bihar, India, on July 1, 1946. He is now a Dutch Citizen. He received his B.Sc. (Eng) degree from Bihar Institute of Technology, Sindri, India, and his M.Sc. (Eng) and Ph.D. degrees from Birla Institute of Technology (BIT), Ranchi, India, in 1968, 1970 and 1979, respectively. Since June 1999, Dr. Prasad has been with Aalborg University, where currently he is Director of the Center for TeleInFrastruktur (CTIF), and holds the chair of wireless information and multimedia communications. He is the coordinator of the European Commission Sixth Framework Integrated Project MAGNET (My personal Adaptive Global NET). He was involved in the European ACTS project FRAMES (Future Radio Wideband Multiple Access Systems) as a DUT project leader. He is a project leader of several international, industrially funded projects. He has published over 500 technical papers, contributed to several books, and has authored, coauthored, and edited eleven books. He has served as a member of advisory and program committees of several IEEE international conferences. In addition, Dr. Prasad is the coordinating editor and editor-in-chief of the Kluwer International Journal on Wireless Personal Communications and a member of the editorial board of other international journals, including the IEEE Communications Magazine and IEE Electronics Communication Engineering Journal. Dr. Prasad is also the founding chairman of the European Center of Excellence in Telecommunications, known as HERMES. He is a fellow of IEE, a fellow of IETE, a senior member of IEEE, a member of The Netherlands Electronics and Radio Society (NERG), and a member of IDA (Engineering Society in Denmark). Dr. Prasad is the advisor of several multinational companies.     

使用IEEE 802.21的WLAN与WiMAX网的融合与切换

为了给移动用户提供最好的无所不在的无线宽带接入,不同无线网的融合是当前通信领域的热点研究。而切换管理又是解决无线网无缝融合的最具挑战性的问题。文中讨论了IEEE 802.11WLAN与IEEE 802.16e移动WiMAX网的融合与切换管理。描述其结构和应用场景,介绍了IEEE802.21,它为介质独立的异类网切换提供了一个信令框架,提出了如何使用IEEE802.21解决WLAN与移动WiMAX网之间的切换,并给出了详细的切换过程。说明了使用IEEE 802.21解决WLAN与移动WiMAX网之间的切换是可行有效的。     

A Robust Authentication Protocol with Non-Repudiation Service for Integrating WLAN and 3G Network

The third-generation cellular systems provide great coverage, complete subscriber management and nearly universal roaming. Nevertheless, 3G systems suffer the high installation cost and low bandwidth. Though WLAN provides hot spot coverage with high data rates, it lacks roaming and mobility support. From users' points of views, the integration of WLAN and 3G systems is an attractive way that will provide them a convenient access to network. When integrating WLAN and 3G, there are still some problems should be concerned in terms of authentication and security, such as authentication efficiency and repudiation problem. In this paper, we review the authentication scheme for WLAN and 3G/UMTS interworking which is specified by 3GPP and propose a robust localized fast authentication protocol with non-repudiation service for integrating WLAN and 3G network. The localized re-authentication protocol can shorten the authentication time delay. On the other hand, with the non-repudiation service, the assumption, that subscriber has to fully trust 3G home operator, can be deleted and the trust management between the independent WLAN operator, 3G visited operator and 3G home operator can be eliminated. In other words, our proposed protocol provides legal evidences to prevent the 3G home operator from overcharge toward the subscriber and also prevent the WLAN operator and 3G visited operator from overcharge toward the 3G home operator. The authentication protocol employs HMAC, hash-chaining techniques, and public-key digital signature to achieve localized fast re-authentication and non-repudiation service.     

WiMAX技术及其在VoIP中的应用探析

简要介绍了WiMAX技术及其特点，分析和阐述了WiMAX上应用VoIP的特性和优势，最后简单描述了一WiMAX上应用VoIP案例的实现过程．     

3G与WLAN的关系

文章对无线局域网与3G的技术特点进行了比较，重点探讨了两种技术的多种网络互通方式，并对两种技术的相互关系和各自定位发表了相应意见。     

3G与WLAN的兼容和竞争

文章介绍了3G和WLAN的标准和技术发展现状,并分别对3G和WLAN的发展前景进行了分析;重点探讨了3G和WLAN之间竞争和兼容的关系,指出3G和WLAN技术的充分融合是未来通信发展的必然趋势。     

LDPC码在WiMAX技术中的应用

WiMAX采用了很多新的技术,其中LDPC码是其采用的关键技术之一。文中介绍了WiMAX中IEEE802．16e标准OFDMA物理层采用的LDPC码的编码技术,阐述了码结构和编码方式,并分析了其在加性高斯白噪声（AWGN）和ITU-3信道下的纠错性能。