On the analysis of switched-beam antennas for the W-CDMA downlink

Smart antennas are widely recognized as an enabling technology for addressing the demand of future wireless network capacity when employed in place of traditional fixed-coverage sector antennas. Furthermore, switched-beam antenna systems offer a robust implementation against multipath propagation effects and reduced complexity that is inherent with fully adaptive implementations. This paper introduces a simple closed-form expression for evaluating the capacity increase of W-CDMA cellular networks employing switched-beam antennas. The expression incorporates the effect of practical antenna patterns and the impact of multipath scattering on code orthogonality, as well as that of pilot signal power. The results show that a reduction in downlink interference of approximately 6 dB can be achieved by installing an eight-beam antenna system in a 120/spl deg/ sector configuration when representative values of these parameters are taken into account.     

2002年中国电子信息百强企业

本刊按国际习惯做法,依据去年公布的百强名单进行了两年的对比,由此可看出各公司排名的升降以及营收的上落。此外,囿于篇幅,并对原分析文字作了适当的删节。     

DSP增强第三代基站设计的灵活性

设计人员正在进行第3代移动通信基站设备的研制。这种新设备将使服务供应商能容纳更多的用户（从而有更多的营收额）,而更重要的是用户获得更高速率的数据服务,包括因特网无线接入和无线视频传输。第3代的数据速率目标为2Mb/s,其标准由3GPP（the 3rd GenerationPartnership Project）制订。设备制造商赢得这个市场的关键在于具有建造一个灵活系统的能力。尽管今日的建议谈的是达到2Mb/s的数据速率,但是明日的10Mb/s速率又该怎么办呢?灵活设计应该使部署的系统能够随着客户的要求与服务提供商的需求而增长。 这种系统设计中的灵活性对服务提供商有很大的经济价值,因为它能延长他们对设备投资获得回报的时间。在     

Signal demodulation in the GSM analyzer of base stations

Acomparative analysis of the noise immunity and computational complexity of variousGSM signal demodulators in the analyzer of base stations has been carried out, and recommendations were provided for the selection of demodulator depending on the signal environment and acceptable complexity of its implementation.     

GSM基站测试方法讨论

近几年,随着寻呼业务的大幅度衰退,无线电监测站的工作重点逐步转向新的无线电业务,其中GSM蜂窝移动系统是目前应用最广泛的系统之一,其基站数量之多,分布之广,设备之多众所周知,因此对GSM基站发射设备的测试就成为监测站必须完成的工作任务。无线电管理最关心的是GSM基站发射设备性能指标,特别是无线发射指标。这些指标规定发射机必须在规定的频率内,特定的时隙以特定的功率发射,从时域和频域两方面规定了发射机的电性能。每一个指标的偏差,都可能引起基站与移动终端通讯协议混乱,造成通话链路中断,又或者引起对其他频率的干扰。为此正…     

CDMA基站干扰的查找和建议

自衢州联通公司自CDMA网络开通以来,反映该公司CDMA正式开通后,用户投诉较多,原因是部分地区话音质量差、掉话较多、手机上线困难。为此,浙江省信产厅无管处立即组织监测站技术人员,与联通和朗讯公司的人员一起进行了为期一周的检查测试,查明了干扰CDMA基站的多种干扰源。查找干扰源的方法1.监测干扰信号。联通CDMA基站目前使用的上行中心频点为833.49MHZ,带宽1.23MHZ。我们使用HP-8549频谱仪,在基站接收机滤波器输出端口J5测试,发现有1-3个尖峰脉冲,幅度约-80dbm左右,带宽约30kHz,大部分干扰脉冲频率不固定,在10kHz范围内无规则…     

EXACT DESIGN OF A WIDEBAND DUPLEXER

After solving the boundary value problem of a waveguide junction,the exact design method ofa wideband duplexer for 4 GHz and 6 GHz relay communication is obtained by using the concept of equivalentcircuits.The theoretical results are in good agreement with the measured data.This design method can beused for other wideband duplexers with similar structure.     

Theoretical design of wideband waveguide circulators

This letter describes the procedure used in designing, by purely theoretical means, wideband waveguide 3-port circulators. An extension of earlier field analysis, together with the usual Polder expressions for ferrite permeability, enables a computer programme to give optimum wideband circulators for any size waveguide with any low-loss ferrite material. Experimental results are given of circulators so designed.     

On the design of a dual-band base station wire antenna

A dual-band base station wire-antenna design is presented. The MoM and the simulated-annealing technique, for optimizing the antenna geometry, are used. The procedure starts from the design of a primary radiator, consisting of a dielectric covered driven dipole and a parasitic element. A Chebyshev antenna array is checked in both the 900 and 1800 MHz frequency bands, with and without the appropriate feed network. All the electrical characteristics, as well as the patterns of the antenna, are presented     

飞蜂窝基站实现了家庭无线互连

可以想象有一种设备,它能够在家庭范围内提供高质量的电话服务,允许家庭成员之间不受限制地进行语音和数据交流,而每月只需要很低的费用.Femto基站通常是指飞蜂窝(Femtocell,也称为毫微微小区),它具有很多功能.这种小型无线设备放置在家庭或办公室内,可以提高本地无线覆盖.     

Software radio issues in cellular base stations

The use of the “software radio” concept in cellular applications is a topic of widespread interest. Two key issues in the implementation of software radios are the development of optimal receivers that require the minimum number of bits in the wide-band analog-to-digital converter (ADC) and efficient channelizers that extract individual channels from the digitized wide-band signal. In this paper, both of these issues are studied in detail for cellular base stations. A computationally efficient wide-band channelizer is presented. This channelizer is closely related to the discrete Fourier transform filter bank used in transmultiplexers. It is shown that the complexity of the proposed channelizer is significantly less (2-50×) than the complexity of conventional channelizers. An optimal receiver that explicitly takes into account the effect of the quantization noise of the wide-band ADC is also derived. The analysis of the ADC noise provides guidelines for specifying wide-band ADC for use in cellular applications. The development of the channelizer and the optimal receiver yield important insights into the implementation of cellular software radios. All of the key results of this paper are applied to a detailed example based on the Digital Advanced Mobile Phone System (D-AMPS, IS-54/IS-136) cellular standard. The bit-error rate (BER) performance simulations of a D-AMPS wide band receiver is presented as a part of this example     

Smart antennas in software radio base stations

The application of adaptive antenna techniques to fixed-architecture base stations has been shown to offer wide-ranging benefits, including interference rejection capabilities or increased coverage and spectral efficiency. Unfortunately, the actual implementation of these techniques to mobile communication scenarios has traditionally been set back by two fundamental reasons. On one hand, the lack of flexibility of current transceiver architectures does not allow for the introduction of advanced add-on functionalities. On the other hand, the often oversimplified models for the spatiotemporal characteristics of the radio communications channel generally give rise to performance predictions that are, in practice, too optimistic. The advent of software radio architectures represents a big step toward the introduction of advanced receive/transmit capabilities. Thanks to their inherent flexibility and robustness, software radio architectures are the appropriate enabling technology for the implementation of array processing techniques. Moreover, given the exponential progression of communication standards in coexistence and their constant evolution, software reconfigurability will probably soon become the only cost-efficient alternative for the transceiver upgrade. This article analyzes the requirements for the introduction of software radio techniques and array processing architectures in multistandard scenarios. It basically summarizes the conclusions and results obtained within the ACTS project SUNBEAM, proposing algorithms and analyzing the feasibility of implementation of innovative and software-reconfigurable array processing architectures in multistandard settings     

Adaptive arrays for narrowband CDMA base stations

Base station antenna arrays are a promising method for providing significant capacity increases in cellular mobile radio systems. This paper examines receiver structures and algorithms to assess the potential capacity gains from the employment of multiple receiver antenna elements, of different sizes, for code division multiple access (CDMA) systems. It considers antenna arrays for the mobile to-base station or reverse link of a CDMA cellular system such as the IS-95 standard. It begins with an introduction to CDMA communication systems and also addresses the general topic of antenna array receivers. Channel modelling is then discussed, as this will influence the design of CDMA receivers. The specific form of receiver array processing algorithms is then discussed and some performance comparisons provided. Finally, the most important reason for implementing antenna array systems, the capacity gains which are achievable, is indicated     

Orthogonal wideband hybrid-coding radar waveforms design

To obtain wideband orthogonal waveforms of radar systems with high-range resolution and good correlation properties, this paper proposes two types of orthogonal wideband hybrid-coding waveforms, polyphase discrete frequency (PDF) waveforms and polyphase signed-chirp (PSC) waveforms. Using an intra-pulse hybrid modulation, high-range resolution can be obtained, and good correlation properties between different waveforms are easier to optimize within a larger optimization space. Specifically, good correlation properties of the PDF waveforms are indeed easier to achieve without a loss of range resolution, as occurs with a discrete frequency coding waveform. Compared with polyphase coding waveforms, the signal bandwidth of each PSC waveform is twice as large as that of sub-pulse chirp signals, and superior correlation properties are obtained. Finally, various designed waveforms optimized by the genetic algorithm are provided to demonstrate the effectiveness of these proposed wideband hybrid-coding waveforms.     

超宽带脉冲信号设计

超宽带无线通信技术是利用极窄脉冲传输的系统,其中脉冲波形是其研究中的重要内容。主要讨论了正弦调制高斯脉冲和Meyer小波脉冲,通过MATLAB仿真分析研究,发现它们与高斯脉冲相比,具有一些优点,可以满足某些特定的要求,能够改善超宽带无线通信系统的性能。     

宽带频率综合器设计中杂散问题研究

频率综合组件的杂散指标影响着整个系统的工作性能。详细介绍一款工作跨X-K波段,带宽9 GHz的频率综合器设计过程中的杂波抑制的解决措施。该款宽带频率综合器的设计包含了锁相、倍频、混频等频综设计主要常用技术,频带拓展主要采用开关滤波器组来实现。方案中电路设计比较复杂,外加控制电路的数字信号干扰,杂散指标一直是调试过程中的瓶颈问题。该频综的杂散主要包含本振泄漏、高次谐波、交调信号以及数字电路的干扰等。通过实验分析,找到杂散的来源,给出解决方法。该频综的设计杂波抑制要求–60 dBc,通过反复调试程序及电路,实现了系统指标要求,9 GHz工作带宽内杂散抑制达到–65 dBc。     

一种短波宽带鞭天线的设计方法

设计了一种短波宽带鞭天线.为缩小天线尺寸和提高工作带宽, 采用集总元件和传输线, 运用加载技术和宽带匹配网络技术相结合提高了天线的宽频带特性, 基于矩量法分析仿真天线性能, 混合遗传算法和差分进化算法进行天线加载和匹配网络的一体化优化.根据综合出的天线参数实际制作了一副短波宽带鞭天线, 通过对比实测与仿真电压驻波比(voltage standing wave ratio, VSWR)曲线, 二者吻合较好, 验证了设计方法的正确性.     

短波宽带接收信道的优化设计

根据现代短波通信的发展趋势,结合现有技术,提出了适用于高线性大动态范围的短波宽带接收信道电路结构。综合分析了噪声系数的计算、信道增益的确定和动态范围的实现,研究了射频信道各部分的指标分配与整机性能指标优化设计,讨论了对器件选择的考虑,提出了自动增益控制的实现方案。在高线性和大动态范围的具体电路实现上具有一定的创新。实际测试结果表明,该接收信道性能满足设计要求。     

Design of wideband dual-band dual-polarized dipole for base station antenna

This article put forward a novel dual-band dual-polarized magneto-electric dipole antenna excited by F-shaped strips. The proposed antenna achieved a common impedance bandwidth of 25.5% and 39.5% in the lower and the upper bands at both input ports, ranged from 0.75 GHz to 0.97 GHz and from 1.73 GHz to 2.59 GHz respectively. The antenna has good performance in isolation, which is more than ?32 dB between the two input ports, and the gain of the antenna is average 4.3 dB and 7.8 dB in the lower and upper bands. The antenna has a stable broadside radiation pattern with low cross polarization and low back lobe radiation over the operating band. Metallic side walls on the ground are added for better performance in gain and radiation pattern.