IEEE 802.11aj(45GHz):A New Very High Throughput Millimeter-Wave WLAN System

This paper presents an overview of a new very high throughput millimeterwave WLAN system operating at 45 GHz band. We begin by reviewing standards process of IEEE 802.11aj(45GHz). Then the frequency spectrum allocation at 45 GHz band is introduced. Next, the channel measurement and mod-eling is given. Specifically, the millimeter-wave MIMO for physical layer enhancement is given in detail.

A NOVEL ESTIMATION METHOD OF TIMING OFFSET FOR OFDM BASED WLAN SYSTEMS

The conventional timing synchronization methods based on time domain correlation have the problems of timing metric plateau in Additive White Gaussian Noise(AWGN) channel and estimation error in multipath fading channel. To resolve the problems, this paper proposes a novel timing metric using the characteristics of long training symbols in IEEE802.11a and a new timing recovery method based on the new timing metric for Orthogonal Frequency Division MuItiplexing(OFDM)-based WLAN systems. The proposed timing metric is defined as a sum of absolute values of the imaginary parts of all the subcarrier samples. It exhibits a unique characteristic that is very sensitive to the true synchronization point since it has minimum value at the true synchronization point and maximum around the true synchronization point. The simulation results show that the performance of timing synchronization is significantly improved, as a result, the probability of error estimation is lower than 10-4 when Signal-to-Noise Ratio(SNR) is more than 10dB.

Neighboring AP discovery and information exchange methods in Plug-and-Play WLAN system

To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.

A shock wave overpressure test system based on WLAN

Due to short transmission distance and low transmission speed when testing the shock wave overpressure with storage test method based on ZigBee technology, a new test method based on wireless local area network （WLAN） technology is proposed, which can monitor remote test nodes. Moreover, the wireless network is designed based on 802. 11b/g protocol, which is helpful for reading the data of the test nodes quickly. Therefore, the accessibility of distributed test system can be improved greatly. The field test results show that the test system performance is good and the transmission speed is high.

Secure Authentication of WLAN Based on Elliptic Curve Cryptosystem

The security of wireless local area network （WI.AN） becomes a bottleneck for its further applications. At present, many standard organizations and manufacturers of WLAN try to solve this problem. However, owing to the serious secure leak in IEEES02.11 standards, it is impossible to utterly solve the problem by simply adding some remedies. Based on the analysis on the security mechanism of WLAN and the latest techniques of WI.AN security, a solution to WLAN security was presented. The solution makes preparation for the further combination of WLAN and Internet.

一种面向WLAN的分布式分层并行仿真方法

针对采用分布式并行方法仿真WLAN(wireless local area network)场景时存在的随终端节点个数增加而效率降低的问题,提出了一种面向WLAN的分布式分层并行仿真方法。基于WLAN的星状网络拓扑结构,令仿真接入节点的进程为主进程,负责WLAN全网中其他仿真节点的时间同步;将所有仿真终端节点的进程均匀分为若干组,由组长负责该组内进程的同步。在主进程广播仿真开始事件后,组长进程先收集本组组员终端节点推进结束消息,当收齐后再向主进程汇报。形成“主进程-组长进程-组员进程”的3层分层结构。在不同计算负荷下,仿真分析并得到了分层仿真方法的时间增益因子闭合表达式。仿真结果表明,与现有不分层的仿真方法相比,当平均计算负荷为1.2倍单位时长、节点个数为100时,所提分层仿真方法的增益可达50%。

基于SystemVerilog和MATLAB参考模型的WLAN基带功能验证

针对WLAN基带芯片的特点与功能验证需求,提出并实现基于SystemVerilog语言和MATLAB参考模型的功能验证方案.并给出该方案中MATLAB参考模型与验证平台的融合,功能覆盖模型的定义以及覆盖率驱动验证机制.使用该方案有效地提高一款WLAN基带芯片的功能验证效率和质量,完成功能验证目标.

Traffic analysis on carrier accessing for WLAN indoor positioning system

Currently,the WLAN indoor positioning system attracts a lot of interests,not only because of the cheap implementation but also because of the high positioning accuracy comparing with other indoor positioning systems.The WLAN indoor positioning system contains two phases,which are offline phase and online phase.In the online phase,the WLAN equipment user(UE) has to access to the WLAN for the latest radio map and positioning software.Due to during the network allocation vector(NAV) duration,the WLAN channel is only reserved for one WLAN UE,others UEs' carrier accessing will be blocked.In addition,the blocked UE will make a retrial accessing,which will definitely introduce more traffic blocking to the WLAN.So In this paper,based on the analysis of the WLAN indoor positioning system architecture,a proper queuing model by using of the Extended Erlang B formula is proposed,which takes the retrial calling percentage into consideration in the proposed model.The simulation results show that the proposed method is more accurate and performs well to predict the blocking probability.

Design of the small microstrip antenna based on the WLAN/UWB wireless communication system

The antenna,as the component of receiving and sending signals in the front end of the wireless communication system,plays an important role in the communication quality,and is often the main obstacle to the development of the miniaturization of the wireless communication system.The microstrip antenna is composed of a metal radiation patch which can be pasted on the dielectric substrate.The choice of the shape of the metal patch can be arbitrary.The conventional shape is usually chosen as the metal patch to simplify the analysis and prediction of its performance.The dielectric constant of the microstrip antenna substrate is relatively low in order to enhance the field intensity of the edge radiation field.However,the dielectric constant of the substrate needs to be greater than 5 in order to meet the needs of other performance of the microstrip antenna,so that the radiation edge effect cannot be enhanced,resulting in the greater contradictions.

Strix Systems携手矽谷星矢推广新一代WLAN产品

中国无线局域网(WLAN)市场近两年快速发展。进入2005年，这一市场仍然保持良性发展态势。

LTE与WLAN技术在轨道交通PIS系统中的应用对比

随着城市交通的不断发展,轨道交通PIS系统在提供实时乘客信息和确保交通系统的高效运行方面变得愈发重要。文中比较了LTE和WLAN两种通信技术在轨道交通PIS系统中的应用。通过性能、可靠性、成本、适用性等方面的比较,揭示了两种技术各自的优势和不足。研究结果有助于决策者选择适当的通信技术,以满足PIS系统的需求,提高系统性能。

WLAN技术在地铁正线停车场景中的应用可行性

随着城市建设的地铁线路越来越多,为节省用地开始提出地铁列车正线停车场景,地铁建设者也开始探讨各种关于正线停车场景的可实施性。WLAN技术能否应用在正线停车场景中,应结合列车正线停车场景对车地无线网络的要求、WLAN技术在地铁常规模式下应用的表现以及对WLAN技术在地铁列车正线停车场景中的应用,确定列车正线停车场景的各种需求。

特高压变电站环境下基于可信WLAN的数据传输安全性分析

作为电力传输的核心节点,特高压变电站运行数据的安全性和稳定性将直接影响到整个电网的运行安全。传统有线通信方式难以满足变电站日益增长的通信需求;无线通信技术因灵活性、便捷性等优点逐渐成为变电站通信的重要补充。然而,在带来便利的同时,无线通信面临数据泄露、非法接入等安全威胁。因此,基于可信WLAN的数据传输安全性成为研究的热点。

3G/WLAN网络中基于终端移动与业务认知的动态负载均衡机制

下一代无线移动通信要求异构网络之间相互协作,3G蜂窝网与WLAN之间的密切合作将为用户提供无缝的业务链接与多样化通信服务.终端移动与业务时空分布的不均衡性是影响网络性能的重要因素,3G/WLAN网络中业务负载均衡策略是提高网络整体性能的有效途径.首先,文中提出了一种新的基于终端移动与业务认知的动态负载均衡(DLB-MSA)机制,该机制重点关注业务潜在用户,通过动态优化的联合业务接入控制,使得每个无线接入点的业务量与其通信资源保持匹配关系,实现网络的负载均衡.然后,为了探讨终端移动对无线网络通信性能的影响,文中创建了一种新的基于2维终端速率分类与状态转换的移动模型,并且给出了相应的Markov分析方法.该模型能够更准确地反映用户移动规律,通过比较简单的参数学习来逼近3G/WLAN网络中终端的群体移动特征.最后,文中基于该模型对DLB-MSA机制进行性能评估,通过仿真验证了该机制的有效性.

基于结构合成法的微型化双频WLAN印刷天线设计

针对当前WLAN技术的快速发展和已有的双频WLAN印刷天线存在增益不足、带宽较窄、尺寸偏大、制作成本高等缺陷的现状,本文借鉴了传统倒F印刷天线和蛇形单极子印刷天线的设计经验,提出了一种新的双频印刷天线设计方法,即结构合成法,并采用该方法设计了一种应用于IEEE 802.11a标准和IEEE 802.11b标准、占用面积仅13.6 mm×9.3 mm的新型微型化双频WLAN印刷天线。采用Ansoft HFSS对比研究了合成前后单频天线和双频天线的性能变化情况,并对双频天线的主要结构进行了分析和优化。仿真结果表明,天线在2.45 GHz和5.45 GHz两个谐振频点上的最高增益分别达2.74 d Bi和2.44 d Bi,相对带宽分别为15.5%和10.6%。此外,文中采用矢量网络分析仪对天线实物进行了测试,实测结果与仿真结果吻合,天线在低频和高频的谐振频点分别为2.53 GHz和5.71 GHz,S11<-10 d B的有效带宽分别超过了400 MHz和500 MHz,展现出了良好的带宽特性。

WLAN Mesh漫游接入认证协议

IEEE 802.11s WLAN Mesh没有定义客户端的漫游认证协议,并且其初始接入认证协议EMSA中,申请者和认证者的认证密钥是通过认证服务器产生的,所以申请者和认证者之后的所有通信完全可以被认证服务器获取.同时该协议中的基于共享密钥的认证方式不能保证前向保密性,一旦长期密钥丢失,由其保护的所有通信内容都将被泄露.在EMSA的基础上,利用三方Diffie-Hell man密钥交换和单独认证载荷技术提出了客户端漫游接入认证协议.该协议不但克服了上述缺陷,而且只需要4轮的协议交互便可以实现上述三者之间的相互认证和密钥确认,不需要4步握手进行密钥确认.并且新的协议将基于签名的认证方式和基于共享密钥的认证方式统一于单独的认证载荷,这样认证方式的改变并不影响认证协议的结构.最后对新的协议进行了可证明安全分析和NS2性能仿真,结果表明:新的协议是通用可组合安全的,并且性能优于现有协议.

一种WLAN与eHRPD系统间负载均衡算法

针对eHRPD、WLAN混合组网时的负载均衡,提出基于网络资源利用率为参考对系统内的用户进行异系统切换,从而使得混合组网后的系统负载得到均衡.通过该整合系统的仿真,在保证无线链路丢失率不受影响前提下,该方法使得蜂窝小区的平均吞吐率有所提高,并能找到使得吞吐率最大时的最佳切换阈值.

基于无线局域网(WLAN)的油田安全监控系统研究

针对油田监控对象具有点多、面广、跨区域的特点,指出对油田进行无线监控的必要性,并对6种常见的无线通信手段的特点进行比较;根据油田安全监控的业务需求,提出基于WLAN技术的油田安全监控系统硬件结构和软件功能设计方案;并结合工程实施案例介绍系统中无线设备的选型、安装和防雷接地等方面的工程问题。该研究成果实现油田的安全监控预警,减少或避免事故发生的可能性,有利于提高油田安全管理的科学性,具有实用推广价值。

WLAN技术在家居智能化中的应用

目的针对智能化家居的特点,应用无线网络技术构建家居智能化网络系统并研究系统可靠性和安全性的解决方法.方法通过对比无线网络的各种技术标准,选择了适合于构建家居智能化网络的ZigBee技术,以此搭建系统组网模型,设计系统软件工作流程,并分别采用DSSS通信技术、差错控制和RADIUS、非对称加密算法解决系统可能存在的可靠性和安全性问题.结果利用无线网关和外部网络连接构成的智能化家居网络,可提供集中和异地的数据通信,使信息在家庭内部和外部之间充分流通和安全共享.结论采用无线网络技术实现的家居智能化网络系统具有有线网络无法比拟的灵活性和可扩展性,给人们的生活带来了更多的便捷、舒适与高效率.

基于ANDSF实现WLAN和蜂窝网间选网机制的增强

随着蜂窝网的不断升级、WLAN热点的广泛部署和智能终端的大量普及,用户希望拥有一致、平滑、高速的业务体验。为了合理地利用网络资源、方便用户选择最合适的接入网,在WLAN和蜂窝网间选择合适的接入网起着重要作用。本文综述了现有接入网发现和选择的相关技术,分析了基于ANDSF(access network discovery and selection function,接入网发现和选择功能)实现WLAN和蜂窝网间选网的局限性,提出了ANDSF机制中基于接入网状态进行接入网选择的方案。