2．4GHzWLAN无线功率放大器的设计与实现

对WLAN无线功率放大器进行了研究,根据WLAN 802.11b/g无线局域网的特点设计出一种工作于ISM2.4 GHz频段的双向收发的功率放大器。该放大器采用特殊的双管平衡放大电路设计,发射信号功率达到500 mW,接收增益大于10 dB,能方便地串接在无线AP上。该放大器的设计采用了Agilent的ADS2004仿真工具,并给出了测试结果。     

基于OPNET的IEEE 802.11战场WLAN增援救助仿真及性能评估

为了在高技术条件下的局部战争中把握战场的主动权，在减少泄密的情况下充分发挥现代战争的神经网络（通信系统）的作用，文章运用OPNET建模技术，设计了一个简单的IEEE 802．11战场无线局域网（WLAN）的拓扑结构．实现了对战场增援救助过程通信情况的仿真。通过对仿真数据分析，对网络的实时性、可靠性、稳定性等性能进行了评估，从而对战场WLAN的设计及使用提供技术上的参考。     

Smart WLAN Discovery for Power Saving of Dual‐Mode Terminals

Dual‐mode terminals (DMTs) equipped with cellular and WLAN interfaces have become popular in recent years. Users of DMTs can enjoy high‐speed WLAN Internet access and wide area Internet access to cellular networks. However, a DMT may consume power inefficiently when discovering a WLAN with inherently limited service coverage. In this letter, we propose to use smart WLAN discovery (SWD) to minimize the power consumption required for WLAN discovery. To minimize the power consumption of a DMT, an SWD DMT activates its WLAN interface only when the DMT transfers data within the WLAN coverage area. The simulation results of SWD show an improved power‐saving performance compared to previous WLAN discovery schemes.     

Power-Efficient Spatial Reusable Channel Assignment Scheme in WLAN Mesh Networks

Interference has strong effect on the available bandwidth of wireless local area network (WLAN) based mesh networks. The channel assignment problem for multi-radio multi-channel multihop WLAN mesh networks is complex NP-hard, and channel assignment, routing and power control are tightly coupled. To mitigate the co-channel interference and improve capacity in multi-channel and multi-interface WLAN mesh networks, a power-efficient spatial reusable channel assignment scheme is proposed, which considers both channel diversity and spatial reusability to reduce co-channel interference by joint adjusting channel, transmission power and routing. In order to assign channel appropriately, an efficient power control scheme and a simple heuristic algorithm is introduced to achieve this objective, which adjust the channel and power level of each radio according to the current channel conditions so as to increase the opportunity of channel spatial reusability. The proposed channel assignment scheme also takes load, capacity and interference of links into consideration. Simulation results show the effectiveness of our approach and demonstrate that the proposed scheme can get better performance than other approaches in terms of throughput, blocking ratio, energy consumption and end-to-end delay.     

An Area-Efficient 4-Stream FIR Interpolation/Decimation for IEEE 802.11n WLAN

This paper presents an area-efficient 4- stream finite impulse response (FIR) interpolation/decimation for IEEE 802.11n wireless local area network (WLAN). Novelty of the presented design is threefold. First, a multi-path pipelined polyphase structure is proposed to deal with multiple data streams, thereby four simultaneous data streams can be supported in the design with minimal hardware complexity. Second, a hybrid common subexpression elimination (HCSE) method that using signed binary representation of coefficients is applied to the implementation of subfilters. The multiplications in each subfilter are efficiently implemented using a few hardwired shifts, adders, and subtracters. And last, the interpolating mode and decimating mode of the design are configurable. That help to improve system level hardware utilization efficiency since WLAN is a time division duplex system. Under 0.13 μm 1.2 V 1P6M CMOS technology, the cell area and power consumption of the presented interpolation/decimation are 0.22 mm² and 10.08 mW respectively. The error vector magnitude (EVM) performance of an 802.11n baseband prototype which adopts the presented design is measured −42.2 dB.     

基于IEEE 802.11协议的WLAN无线资源管理浅析

本文研究了WLAN(无线局域网)中的无线资源管理问题.首先基于MAC分离的思想给出了一种新的WLAN框架结构,然后在此框架结构的基础上,分析了信道分配、功率控制以及负载均衡等无线资源管理问题,提出了相应的解决方案.在WLAN中引入无线资源管理技术,可以大幅度地提高WLAN的性能和容量.     

Multilevel outphasing system using six-port modulators and doherty power amplifiers

In this paper, a simple and efficient architecture for implementation of multilevel outphasing systems is presented. The architecture consists of a six-port modulator and a Doherty power amplifier in each outphasing branch. Pin diodes are used as variable impedances of the six-port modulator and their parasitic elements are analytically compensated. A prototype of the variable load is fabricated and the results show the effectiveness of compensation method to prepare pin diodes as variable loads for a six-port modulator. As a proof of concept, a standard 2.4 GHz Doherty power amplifier is designed with 65% efficiency at peak power and 46% efficiency at 6 dB back off. The proposed system is simulated in advanced design system using a 20 MHz WLAN signal with 7.5 dB PAPR and 5 level outphasing. Simulation results show 31.6% power added efficiency for the Doherty-Outphasing system.     

基于IEEE 802.11协议的WLAN无线资源管理浅析

本文研究了WLAN（无线局域网）中的无线资源管理问题。首先基于MAC分离的思想给出了一种新的WLAN框架结构,然后在此框架结构的基础上,分析了信道分配、功率控制以及负载均衡等无线资源管理问题,提出了相应的解决方案。在WLAN中引入无线资源管理技术,可以大幅度地提高WLAN的性能和容量。     

Security protocol for IEEE 802.11 wireless local area network

As Wireless Local Area Networks (WLANs) are rapidly deployed to expand the field of wireless products, the provision of authentication and privacy of the information transfer will be mandatory. These functions need to take into account the inherent limitations of the WLAN medium such as limited bandwidth, noisy wireless channel and limited computational power. Moreover, some of the IEEE 802.11 WLAN characteristics such as the use of a point coordinator and the polling based Point Coordination Function (PCF) have also to be considered in this design. In this paper, we introduce a security protocol for the IEEE 802.11 PCF that provides privacy and authentication, and is designed to reduce security overheads while taking into account the WLAN characteristics. We prove this protocol using the original and modified BAN logic.     

An efficient power-saving mechanism for integration of WLAN and cellular networks

In this letter, we propose an efficient power-saving mechanism using paging of cellular networks for WLAN in heterogeneous wireless networks, where WLAN interface is turned off during idle state without any periodic wake-up in order to save power consumption while at the same time, the existing paging of cellular network is utilized in place of beacons in WLAN. For the proposed mechanism, the mean power consumption is investigated via analytical and simulation results.     

Effects of Power Amplifier Distortion and Carrier Frequency Offset on the Performance of WLAN System

Due to the efficiency of mitigation multipath delay spread, orthogonal frequency division multiplexing (OFDM) is extensively used in the wireless local area network (WLAN) domain, such as the IEEE 802.11a standard defined by the IEEE 802.11 standardization group and the HIPERLAN/2 defined by the European Telecommunication Standards Institute Project on Broadband Radio Access Networks. OFDM based WLAN system is very sensitive to the power amplifier distortion and the carrier frequency offset. The performance of the OFDM based WLAN system in the presence of the power amplifier distortion and the carrier frequency offset under practical fading channel is researched and analyzed in this paper. A closed form of bit error rate (BER) is derived for the OFDM based WLAN system in the presence of the power amplifier distortion and the carrier frequency offset under practical fading channel. The effects of the power amplifier distortion and the carrier frequency offset on the OFDM based WLAN system performance are comparatively studied by the theoretical method and by the simulation method under practical multipath fading channels. Studies show that the theoretical and simulated results match well.     

802.11基带处理芯片中GFSK调制解调系统的实现

无线局域网是一种短距离无线通信系统。本文介绍了802．11协议中GFSK的调制原理，并提出了一种低成本、低功耗的GFSK调制解调实现方案，可应用于802．11基带处理芯片的设计中。     

基于无线局域网的矿下定位卡设计与实现

在无线局域网矿井定位系统中,定位卡是配置给矿井工作人员随身携带的嵌入式设备,应满足重量轻、体积小、抗干扰、低功耗等多方面的要求。文中从硬件和软件两方面对定位卡的设计与实现进行了叙述,同时提出了若干解决定位卡的非功能性要求的设计方法。     

基于负载牵引技术的射频功率放大器设计

本文描述了微波电路中基于负载牵引技术的WLAN功率放大器的设计方法。笔者采用CMOS工艺设计了两级差分放大电路,并对该差分放大电路进行负载牵引。在此基础上,我们设计了输入输出匹配网络,最后使用ADS软件进行整体仿真。结果表明,在1．8V电源电压下,放大器增益为29dB,1dB压缩点的输出功率为18．3dBm,功率附加效率为16．8％,满足系统指标要求。     

5GHz0．18μm CMOS功率放大器设计

文中介绍了一个基于TSMC 0．18μm CMOS工艺,可应用于802．11a无线局域网标准的功率放大器设计。该电路采用三级全差分结构,驱动级采用电阻并联负反馈网络来保证稳定性。在3．3V电源电压下,增益为16dB,输出1dB压缩点为17dBm,电路功耗为0．8 W,效率为18．1%。芯片面积为1．2mm×1．1 mm。     

一种基ARM7的无线局域网 MAC片上系统架构

提出了一种ARM7TDMI核和先进微控制器总线架构的无线局域网MAC控制器片上系统方案,对各个组成模块进行了详细描述,并从设计复杂度、功耗、性能等方面对其该方案和其他方案进行了分析和比较.     

WLAN的无线传输技术及网络规划

文章介绍了IEEE802．11b标准采用的频段特点及中国有关部门对该频段的政策，描述了无线收发信机采用的扩频、功率控制与分集接收等技术。给出了无线局域网电波传输模型，最后结合无线局域网技术特点及室内电波传播方式。提出了无线局域网的网络规划方法与策略。     

用于微波放大器的InGaP HBT微波动态大信号波形特性

In wireless mobile communications and wireless local area networks （WLAN）, advanced InGaP HBT with power amplifiers are key components. In this paper, the microwave large signal dynamic waveform characteristics of an advanced InGaP HBT are investigated experimentally for 5.8 GHz power amplifier applications. The microwave large signal waveform distortions at various input power levels, especially at large signal level, are investigated and the reasons are analyzed. The output power saturation is also explained. These analyses will be useful for power amplifier designs.     

Microwave dynamic large signal waveform characterization of advanced InGaP HBT for power amplifiers

In wireless mobile communications and wireless local area networks (WLAN), advanced lnGaP HBT with power amplifiers are key components. In this paper, the microwave large signal dynamic waveform characteristics of an advanced InGaP HBT are investigated experimentally for 5.8 GHz power amplifier applications. The microwave large signal waveform distortions at various input power levels, especially at large signal level, are investigated and the reasons are analyzed. The output power saturation is also explained. These analyses will be useful for power amplifier designs.     

无线网状网组网技术及实验研究

面对日益增长的高速无线因特网接入需求,传统的无线接入方式,如蜂窝网、无线局域网（WLAN）面临许多挑战,而无线网状网（WMN）作为因特网“最后一公里”接入方案,提供一种灵活而低成本的多跳通信,也将成为各种无线网络融合的主要技术。针对这一极具发展前途的网络结构,从WMN的两种典型应用出发,文章从网络配置、功率控制、移动性管理和接入控制以及路由协议设计等方面说明了WMN组网中的相关问题和技术,对WMN与移动自组织（Ad hoc）网路由协议的设计进行了对比,并给出了一种基于WLAN和第二层交换技术的WMN试验床实现方案。