无线局域网标准的最新发展

目前，曾经火爆一时的无线通信并不一帆风顺，蓝牙、3G都不同程度受到了挫折，或者是比预期发展得缓慢或者是商用时间被迫推迟。只有无线局域网技术一枝独秀。最早的无线局域网主要用在仓库和工厂里，而现在却安装在办公室、住宅，甚至是公共场所。人们熟知的无线局域网的标准是IEEE802.11b（也称作Wi-Fi或无线以太网），现在，IEEE又制定了新的802.11a和802.11g标准，希望能够提高传输速率以便可以和铜线甚至光纤抗衡。但是IEEE的802.11系列的802.11b、802.11a、802.11g这三个标准都存在着安全问题。IEEE将推出一些补充的标准来解…     

WLAN安全机制

随着无线局域网技术的广泛应用,新的无线局域网安全标准被提出以增强无线局域网的安全性能.本文介绍了IEEE 802.11i和WAPI两个无线网络安全技术标准的实现机理和具体流程,重点分析了我国自主研发的WAPI的技术特征和应用状况,并将其与IEEE 802.11i技术标准做了分析对比.     

Compact internal multiband antenna for mobile phone and WLAN standards

A novel internal planar inverted-F antenna (PIFA) suitable for handset terminals is presented. The structure combines shorted parasitic patches, capacitive loads and slots to achieve multiband operation. This compact antenna operates in the GSM, DCS, PCS, UMTS, HIPERLAN/2 and IEEE 802.11a bands within 2.5:1 voltage standing wave ratio (VSWR) and with good efficiency.     

无线局域网技术、标准及热点宽带无线通信技术

首先介绍了无线局域网技术及802.11系列标准,进而评述了无线通信发展趋势和主要技术,最后展望了无线通信产业未来发展的方向.     

Handover management in integrated WLAN and mobile WiMAX networks [recent advances and evolution of WLAN and WMAN standards]

Recently there has been much effort, in both academia and industry, to integrate a plethora of wireless technologies in order to provide ubiquitous broadband access to mobile users. Handover management is still one of the most challenging issues to be solved for seamless integration of wireless networks. This article addresses the integration of IEEE 802.11 WLANs and IEEE 802.16 WMANs, focusing mainly on the handover management aspects. First, we describe architectures, futuristic application scenarios such as the envisioned heterogeneous multihop wireless networks (HMWNs) and moving networks, as well as the related research issues. Second, we present IEEE 802.21, a new emerging standard aimed at providing a framework for media-independent handover (MIH) among heterogeneous networks. Finally, we discuss how the MIH framework can help handover management for the integrated network.     

Recent advances and evolution of WLAN and WMAN standards [guest editorial]

Standardization of wireless technologies is a continuous process, and even established standards are updated and modified in response to changes in the technology and the marketplace. One such example is the successful IEEE 802.11 standard for wireless local area networks (WLANs), which was originally designed for 1 and 2 Mb/s traffic, and is now being upgraded to support 600 Mb/s in 802.11n and being considered as a high-throughput (up to 1 Gb/s) wireless interface for the nomadic scenarios of the next generation of wireless systems. Similarly, enhancements to the IEEE 802.16 standard for wireless metropolitan area networks (WMANs) are being considered to develop a mobile air interface with support for up to 100 Mb/s in high mobility scenarios. This continuous evolution of the IEEE 802.11 WLAN and 802.16 WMAN standards is made possible with new innovation and contribution from both academia and industry. Given the rapid growth of these technologies, it is important to understand what new application scenarios have triggered the recent developments within WLAN and WMAN standards, how they are evolving, the technological challenges they face, and the opportunities for both the industry and research communities. In this issue, from a large number of submissions, we have selected five key articles for inclusion, which provide the reader with ongoing developments in these standards, technology roadmaps, current research challenges, and comprehensive evolution of these technologies, as well as deployment experience and application requirements.     

WAPI:无线局域网的新国标实施方案的研究

本文将从基于802.11的无线局域网的拓扑结构出发,对其安全问题进行分析,并对 WAPI标准进行剖析,着重突出其在安全性上所具有的优越性,最后提出适合目前国情的应用方案, 希望借此能为中国实施自己的无线局域网标准带来一些帮助。     

3G技术演进及标准化进展

介绍世界两大移动通信标准组织3GPP和3GPP2研究3G技术演进工作的情况,着重说明3G演进的需求和关键技术.     

无线局域网技术及组网方式

无线局域网采用的技术主要有窄频微波、扩频及红外线技术,扩频技术为主流。无线局域网目前有许多不同的标准,处于并存的状态;但从长远看,随着产品和市场的发展,它们将走向融合。无线局域网的组网方式主要有对等网络的基础结构网络两种。     

无线局域网技术和应用

简述了无线局域网（WLAN）的组成，网络拓扑结构和安全性，并分析了WLAN的关键技术，WLAN技术的优劣和WLAN的实际应用，以及中国移动开展WLAN业务的市场前景和盈利模式。     

无线局域网初露锋芒

无线局域网有自己独特的优势,市场前景很好。在电信业不景气的大环境下,巳获得了可喜的发展,具有了一定市场规模。目前相关组织正在促进其产品和网络之间的相互兼容,目的是不断地扩大它的覆盖范围。但说无线局域网会威胁到3G还为时过早,要想在无线通信市场获得实质的发展,还有很长的路要走。     

WLAN的安全性

无线网络与有线网络不同，容易被攻击、截听，安全性易受到威胁。安全问题得不到解决，大规模应用就无从谈起。详细解析了几种主要的WLAN安全标准，简要指出了现有WLAN安全标准的不完善之处。最后，从制造商、运营商和终端用户的角度对W/LAN安全措施的实施进行了探讨。     

WLAN工程设计

本文就WLAN工程设计提出了带有普遍意义的概念,包含室内覆盖、室外覆盖、室外(视距内)无线桥接。并就无线侧的规划、优化进行了浅析。     

IEEE 802.16J relay-based wireless access networks: an overview [recent advances and evolution of WLAN and WMAN standards]

Multihop wireless systems have the potential to offer improved coverage and capacity over single-hop radio access systems. Standards development organizations are considering how to incorporate such techniques into new standards. One such initiative is the IEEE 802.16j standardization activity, adding relay capabilities to IEEE 802.16 systems. This article provides an overview of this relay-based technology, focusing on some of the most pertinent aspects. In particular, the different modes of operation (transparent and non-transparent), framing structures, and network entry procedures are described. Some consideration of the issues in designing such systems is then given, which highlights when different features within the standard are most appropriate. As these systems are very new, many open issues remain to be resolved.     

无线局域网技术及其应用

阐述了无线局域网的四种互联方式:网桥连接型、基站接入型、HUB接入型及无中心结构,对802.11标准、蓝牙、HomeRF和IrDA四种无线局域网的协议标准进行了分析,揭示了无线局域网的安全隐患,对无线局域网的优势和劣势进行了细致的分析。     

WLAN收发器

在基于802.11b无线通信网络标准元器件的支持下,这种网络逐步成为企业通信的主要选择方案。IEEE 802.11b为手提电脑或其它手持终端提供了一条接入网络资源的便利途径,从而增强了现有无线装置的功能。这种接入方式为那些需要在办公室或公共场所(如机场、酒店)临时工作的人员提供了便利;在实验室或其它需要设备频繁移动的办公场所,无线接入网络的出现省去了以太网物理接口重新布局的工作。在市场需求的推动下,Maxim针对IEEE 802.11b无线局域网(WLAN)标准研制了RF收发器和功率放大器。MAX2820和MAX2821是单片、零中频收发器,专为工作…     

System-level modeling of IEEE 802.16E mobile wimax networks: Key issues [recent advances and evolution of WLAN and WMAN standards

WiMAX1 has attracted a lot of attention recently in the telecommunication community including researchers, product developers, and service providers. Numerous papers have been published on various design issues of WiMAX networks. Since the issues being discussed are usually ahead of product availability, most of these studies require simulation. It is important to have some common features among these models so that their results can be compared. Therefore, the Application Working Group of the WiMAX Forum has developed a standard simulation methodology that describes the key features to be simulated, the method of simulating these features, and various parameter values to be used. This system-level methodology has been used in several public and commercial WiMAX simulation models. This article presents a summary of the simulation methodology, and discusses the key issues and common mistakes in simulating various features of network configuration, and the physical, MAC, and application layers.     

无线局域网技术及发展

首先介绍了无线局域网(WLAN)技术标准的现状，分析了WLAN技术的特点。然后从设备、网络、标准等方面对WLAN技术的发展情况进行了分析。     

无线局域网络及3Com公司解决方案

信息革命到今天,我们越来越离不开计算机网络,无论是信息共享、合作伙伴交流、还是移动用户办公,都有网络价值的体现。网络已经渗透到了个人、企业以及运营商。现在的网络建设已经发展到无所不在,不论你在任何时间、任何地点都可以轻松上网。网络无所不在其实并不简单,光靠光纤、铜缆是不够的,毕竟在许多场合不允许铺设线缆。因此,需要推广一种新的解决方案,使得网络的无所不在能够得以实现。这种解决方案就是无线数据网络。     

无线局域网中的认证和计费

无线局域网是计算机网络与无线通信技术相结合的产物。对运营商来讲，它是接入网的补充，具有极大的移动性和灵活性，得到了业界的广泛关注，有着极好的运营前景。首先介绍无线局域网技术基础，进而给出利用美国思科公司AC产品实现运营商开展此项业务所必须考虑的用户认证和计费的组网方案和具体流程。