从cdmaOne到Cdma2000的无缝演进路径

在２０００年世界无线电大会上，第３代移动通信系统（３Ｇ）的地面系统被确定可使用５种无线传输技术，它们是ＣＤＭＡ－ＤＳ、ＣＤＭＡ－ＭＣ、ＣＤＭＡ－ＴＤＤ、ＴＤＭＡ－ＳＣ和ＴＤＭＡ－ＴＤＤ。其中前３种基于ＣＤＭＡ（码分多址）技术，后两种基于ＴＤＭＡ（时分多址）技术。可见，在３Ｇ标准中，ＣＤＭＡ是主流技术。ＣＤＭＡ（Ｃｏｄｅ Ｄｉｖｉｓｉｏｎ Ｍｕｌｔｉｐｌｅ Ａｃｃｅｓｓ）蜂窝系统由于采用了一种称之为扩频的通信技术，所以与采用ＴＤＭＡ和ＦＤＭＡ（频分多址）的ＧＳＭ蜂窝系统相比，具有抗干扰性好、系统容量…     

美国两家公司合作开发数字音频DSP

美国数字无线电公司（ＵＤＲ）与Ｔｅｘａｓ设备公司（ＴＩ）于７月宣布,他们将合作开发用于数字ＡＭ／ＦＭ无线电接收机的数字信号处理器（ＤＳＰ）．预计,这种接收机将于２００１年初在美国市场商品化．这两家公司计划把数字无线电公司的软件与ＴＩ公司的ＴＭＳ３２０Ｃ６０００相结合用于支持带内同频（ＩＢＯＣ）数字音频广播的数字信号处理器．美国正式的数字ＡＭ／ＦＭ广播预计于２０００年中期开始实施．一旦得到美国政府的批准,美国的广播机构就可以开播他们的业务．数字无线电广播技术能使人们用收音机收听到ＣＤ质量的ＡＭ和Ｆ…     

软件无线电技术及其在3G中的应用

软件无线电（Ｓｏｆｔｗａｒｅ Ｒａｄｉｏ）的概念是由美国科学家Ｊｏｅ·Ｍｉｔｏｌａ于 １９９２年 ５月在美国电信系统会议上首次明确提出的。软件无线电的基本概念是将硬件作为无线通信的基本通用平台,而用软件实现尽可能多的无线及个人通信功能。软件无线电的核心是将宽带Ａ／Ｄ和Ｄ／Ａ尽可能靠近天线（将Ａ／Ｄ和Ｄ／Ａ由基带移到中频甚至射频）,用实时高速ＤＳＰ／ＣＰＵ代替传统的专用数字电路做Ａ／Ｄ转换后的一系列处理,将无线通信的各种功能用软件进行定义。 一、软件无线电的特点 随着现代国防和民用设施对通信技术的要求…     

软件无线电技术

（三）一种多模式兼容的软件无线电接收机方案１引言可以用软件无线电台实现频分多址（ＦＤＭＡ）、时分多址（ＴＤＭＡ）与码分多址（ＣＤＭＡ）公用的模拟与数字蜂窝通信系统。这里介绍一种利用软件无线电设计的多模式兼容的接收机,它可以将全球移动通信系统（ＧＳＭ）...     

软件无线电技术

软件无线电技术林福华（东南大学移动通信国家重点实验室,南京,２１００９６）（二）软件无线电中的模数转换１引言模数（Ａ／Ｄ）转换器和数模（Ｄ／Ａ）转换器是软件无线电的关键部件之一。为了使软件无线电接收机在实现Ａ／Ｄ转换后进行数字信号处理（ＤＳＰ）,要求...     

机载PD雷达的无线电校正通道

简述了机载ＰＤ雷达对先进中距离空－空导弹（ＡＭＲＡＡＭ）的制导过程。介绍了国外机载ＰＤ雷达无线电校正通道的研制情况。论述了无线电校正通道的编码及工作过程。     

SCDMA技术在无线接入中的应用

本文简要介绍了ＣＤＭＡ技术 及ＳＣＤＭＡ无线接入中的风步ＣＤ－ＭＡ、软件无线电、智能天线等关键技术。最后介绍ＳＣＤＭＡ无线接入设备及 主要技术特性。     

个人数字蜂窝陆地移动通信网PDC

一、ＰＤＣ网的主要优点ＰＤＣ网是日本于１９９３年首先实现的,它的主要优点有：（１）节省基站相关资源。ＰＤＣ采用３个ＴＤＭＡ信道（半速率编码为６个ＴＤＭＡ信道）,有效地利用基站（ＢＳ）资源和ＢＳ与移动业务交换中心（ＭＳＣ）之间的传输线。（２）无线电频率利用率高。ＰＤＣ采用移动站辅助越区切换方式,改进了切换技术,因此可以使用更小的蜂窝区。（３）通信质量高。ＰＤＣ采用数字信号处理技术,有效地改善了通信质量。（４）信令协议先进。ＰＤＣ采用类似于ＩＳＤＮ用户链路及节点间协议,可以在网络中提供部分多媒体业务…     

CDMA蜂房系统的综述

本文对码分多址（ＣＤＭＡ）进行了一般性的阐述，分析了ＣＤＭＡ中特有的功率控制方案，描述了蜂房环境中宽带波传的一个有趣结果（在蜂房宽带信号上，短期衰落减少，且城市比郊区衰落要少）。本文列出了采用ＣＤＭＡ的一系列优点，充分地讨论了ＣＤＭＡ中的无线电容量。     

软件无线电在我国第三代移动通信系统中的应用

本文首先回顾第三代移动通信系统的研究动态,并着重对我国提出的Ｓ－ＣＤＭＡ系统进行分析比较。得出软件无线电技术是确立我国第三代移动通信系统的关键技术之一。本文还提到Ｓ－ＣＤＭＡ采用软件无线电后新开辟的测向定位功能。     

软件无线电技术的现状与发展趋势

自20世纪90年代初以来,移动通信领域一场新的技术革命悄然兴起,这就是以软件无线电为特征的新一代通信系统研究与开发。软件无线电(SWR)技术是第三代移动通信系统和军用电台的发展趋势。文章主要介绍了软件无线电的概念、软件无线电的关键技术、软件无线电的应用和软件无线电的发展趋势。     

The Automatical Slotted-Line System Controlled with Micro-Computer IBM 80486

This paper reports an automatical slotted-lin system which has been developed by us. This system is controlled with IBM-PC 80486. Its software is designed with C Language. It can performs a variety of measurements such as high, medium and low SWR measurement, signal source SWR, attenuation, phase shift, scattering coefficient of two port network and dielectric constant measurement etc. rapily, exately and conveniently. In this paper, the hardware composition and software design are described. A series of typical measurement results of SWR at 30MM wave-band are given. This method is adaptable for MM-Wave band and other Micro-wave band.     

宽频带低噪声放大器设计

采用Lange耦合器的宽频带特性设计L／S波段平衡式低噪声放大器电路,并通过仿真设计软件对放大器的工作频带、噪声系数、增益及输入、输出驻波比等几个重要指标进行优化。最后设计的放大器在1．2～2．5GHz频率范围内增益为33～35dB,噪声系数不大于1dB,输入输出驻波比小于1．5,达到了预定的技术指标要求,性能良好。     

Efficient sample rate conversion for software radio systems

An efficient sample rate conversion (SRC) method for software radio (SWR) systems is proposed. The proposed method modifies conventional single- or multistage SRC processes such that the computation of the output of a particular stage is performed in a hierarchical fashion. This SRC method consumes fewer computations than traditional SRC methods over a range of SRC factors and is especially suitable for SWR base station transmitters. The computational requirements of the proposed SRC method and conventional SRC methods are compared and simulation results of the proposed method are discussed.     

用于超宽带技术的二元螺旋天线阵研究

分析了螺旋天线的研究方法,讨论了单个螺旋天线元实现宽带与提高增益的矛盾,并提出了相应的改善方法。用多层介质板集成2个辐射区直径不同的螺旋天线以获得低驻波比和宽频带,而且还对这种螺旋天线的增益和驻波比如何受其尺寸大小变化进行了研究,使得这种改进型的螺旋天线能够克服单个天线的缺点,在保证较好增益的前提下实现超宽带。利用著名的仿真软件HFSS10.0和ADS2005进行仿真设计和优化,最终仿真设计了一副适用于超宽带通信系统的微带天线。     

宽带低噪声放大器ADS仿真与设计

介绍一种X波段宽带低噪声放大器（LNA）的设计。该放大器选用NEC公司的低噪声放大管NE3210S01（HJFET）,采用微带阻抗变换型匹配结构和两级级联的方式,利用ADS软件进行设计、优化和仿真。最后设计的放大器在10~13 GHz范围内增益为25.4 dB±0.3 dB,噪声系数小于1.8 dB,输入驻波比小于2,输出驻波比小于1.6。该放大器达到了预定的技术指标,性能良好。     

Adaptive prediction and cancellation digitization method for wideband multistandard software radio base-station receivers

In this study, a new method for digitizing a combination of different analog signals occupying significantly different bandwidths and having a very high dynamic range is proposed and analyzed. Since it is based upon signal-prediction/cancellation principles, it is referred to as adaptive prediction and cancellation digitization (APCD) method and is applied to various families of signals simultaneously received by a multistandard software radio (SWR) base-station receiver. It is shown theoretically and by means of computer simulations that the APCD method can effectively reduce the high dynamic range of the signals before digitization takes place. Hence, the stringent analog-to-digital-converter (ADC) resolution requirements imposed by the operation of such SWR base-station receivers can be significant relaxed. The signal dynamic-range reduction is achieved by applying appropriate signal processing techniques, e.g., autoregressive (AR) and periodic autoregressive (PAR) prediction. Such techniques allow accurate prediction and subsequent cancellation of high-power narrowband signals present among the composite received analog signal. As these signals usually have cyclostationary statistical characteristics, analysis and performance evaluation of AR and PAR predictors, when used to predict cyclostationary signals, were presented. A new adaptive algorithm for implementing the PAR predictor is also proposed, and its validity is justified by theoretical analysis as well as by various performance evaluation results obtained by means of computer simulations.     

Full characterization of gain and noise boundaries for NF<Subscript>min</Subscript> or unity SWR<Subscript>out</Subscript> operation

For a receiver sub-block , Low Noise Amplifier is the first stage after the receiving antenna and as a key device, its amplification and noise figure (NF) affects the whole performance of the receiving part. In this paper we present a full graphical visualization in terms of gain, standing wave ratio (SWR) and noise for a GaAs HJ-FET transistor in two operating cases; (1) NF_min, (2) Unity \(\hbox {SWR}_{\mathrm{out}}\). The set of curves and contours presented will provide the designer with enough visual information about the transistor operating boundaries and will also visually assist on choosing the appropriate matching points for a wideband operation according to the desired (transducer gain \(\hbox {G}_{\mathrm{T}},\hbox {SWR}\)) for case (1) and (\(\hbox {G}_{\mathrm{T}},\hbox {SWR}_{\mathrm{in}},\hbox {NF}\)) for case (2). Numerical examples are given for each operating case and verified via a microwave circuit design software package to demonstrate the adequacy of the proposed graphical techniques . The results from simulations compare favourably with the visually estimated values.     

无线网络中高效的匿名漫游安全协议

无线漫游安全(Secure Wireless Roaming,SWR)协议允许隶属于本地服务器的用户漫游到外地时,可以与外地服务器互相验证身份并建立安全的会话密钥.在此基础上,匿名SWR协议能保证即使所有外地服务器串通情况下漫游用户的匿名性和不可追踪性.该文提出了一个匿名的无线漫游安全协议SYM-SWR (SYMmetric key based SWR).而且就目前所知,该协议是第1个完全基于对称密钥的匿名SWR.同其他已知协议相比,SYM-SW的通信复杂度和计算复杂度均最低.因为SYM-SWR只需要4次消息传送,且不需要PKI (Public Key Infrastructure)而采用消息验证码(Message Authentication Code,MAC)和对称密钥加密这两种高效的运算.     

Rigorous analysis of three-dimensional structures incorporatingdielectrics

The paper presents the SR3D software (3D radiating structures), which calculates the electromagnetic characteristics of arbitrarily shaped structures incorporating dielectric material. The rigorous analysis method is based on the integral equation formulation. The authors included a variational approach using the reaction concept of Rumsey. The problem is numerically solved with a surface finite elements method. A guided mode excitation has been introduced in order to compute the reflection coefficient at the transmit port and the transmission coefficient between the different parts fed by guided modes. This software is validated by excellent agreement between simulated and measured radioelectric performances (patterns and SWR)