基于改进粒子群算法的无线传播模型校正

为提高无线网络规划中路损预测精度,本文在分析无线传播模型校正理论及基本粒子群算法的基础上,提出了合理的适应度函数和粒子编码形式设计,研究了改进的粒子群算法在无线传播模型校正领域的应用.仿真结果表明,该算法正确有效,且校正结果精度优于传统算法.     

基于路测数据的TD-SCDMA网络室外传播模型校正研究

无线传播模型是用来对无线电波的传播特性进行预测的一种模型。传播特性的预测是无线网络规划的基础,其准确性影响到网络规划的准确性和质量。本文针对连续波测试传播模型校正方法所存在的低效率和低准确性等问题,提出了一种利用现网路测数据进行传播模型校正的方法,从理论上证明了路测信号可以替代连续波测试信号用于传播模型校正。本文使用校正的传播模型是SPM模型。     

A市WCDMA无线传播模型校正技术研究

在3G无线网络规划时,为了尽可能减少误差,提高无线覆盖预测和干扰预测的精度,需要对采用的传播模型进行参数校正。本文从传播模型校正原理和方法入手,结合测试环境,对A市市区WCDMA无线传播模型进行校正,并对校正结果进行验证。     

一种基于聚类分析的传播模型选择策略

传播模型是现代移动通信无线网络规划中用于预测路径损耗的重要工具，传播模型选 取的正确性对网络规划的准确性造成很大的影响。提出了一种基于聚类分析的传播模型选择策略。该 策略利用聚类分析的方法，根据扇区覆盖范围内的传播特点为扇区选择校正传播模型，以克服传统的传 播模型选择方法存在的缺点，控制路径损耗预测误差，同时达到降低成本的目的。     

DTMB单频网规划中电波传播模型的选取与校正

研究了某地区DTMB单频网规划中电波传播模型的选取和校正方法,基于连续波测试理论采集和处理实测数据,基于ICS telecom仿真对不同电波传播模型下的接收功率进行预测,以预测值和实测值之间的均方误差最小为准则选取了一种适合该规划地区的电波传播模型,并采用最小二乘法对该模型进行校正,得到两种不同传播环境下(市区、郊区)的电波传播模型。与原模型相比,校正后模型对链路损耗预测的均方误差有较大程度改善,这对提高该规划地区单频网规划的科学性、准确性和可靠性有重要的作用。     

基于地物类型矢量距离的4G LTE传播模型选择方法研究

提出基于地物类型矢量距离的4G LTE传播模型选择方法,根据地物类型最小矢量距离,为无CW测试校正的城市或场景选取合适的传播模型.通过对二维不加权、二维加权和多维加权选择方法得到的传播模型与该区域实测得到的传播模型进行覆盖预测仿真结果对比,证明多维加权矢量距离选择方法可靠性最高,对4G LTE网络精细化规划和工程建设具有实际指导意义.     

WCDMA/TD-SCDMA CW测试与李氏定理

随着我国移动通信网络的飞速发展,各运营商越来越重视传播模型与本地环境的相匹配.无线传播环境复杂、差异性大,因此必须通过实际的传播模型的测试与校正来真实反映无线传播特性.     

如何用Eagle进行TD-SCDMA传播模型测试

1 仪表的选择 由于TD-SCDMA网络在覆盖、容量和QoS之间存在相互影响,因此在网络建设之前,需要对网络进行合理规划.其中,传播模型校正是整个过程的关键之一,其准确度将直接影响无线网络规划的规模、覆盖预测的准确度以及基站的布局情况.为了获得符合本地区实际环境的无线传播模型,提高覆盖预测的准确性,需要对各种地形地貌的传播模型进行校正.     

2.6GHz频段传播模型校正及分析

统计传播模型是目前网络规划的常用手段,SPM模型是典型的统计模型,常用于传播模型校正.目前TD-LTE实验网城市的2.6GHz的传播模型校正工作已经完成,获得重新校正后的SPM模型,且对各个城市传播特性有较全面的认识和理解.各个城市之间的测试结果和校正结果已有初步结论.这些成果和结论对现有的TD-LTE网络规划和优化具...     

神经网络传播模型的设计与应用

传播模型是网络规划的基础之一,其对路径损耗的准确预测能力从一定程度上决定了网络规划的质量。在工程中得到广泛应用的经典传播模型在预测本地无线环境引起的路径损耗方面存在不够准确的缺点。提出了一种以人工神经网络为核心的自适应传播模型,通过利用现网路测数据对神经网络进行训练,充分利用神经网络所具备的高度非线性映射能力和自适应性,使其具备根据本地无线环境特征准确预测传播损耗的能力。实验表明,基于神经网络的传播模型对本地无线环境引起的路径损耗预测的准确性比经典模型更好,并且其适用性也较强。     

一种改进的PID参数整定方法

当使用先进策略整定PID控制器参数时,往往要依赖于系统所辨识的对象模型。为了降低对系统模型的依赖性,提出了一种基于同时扰动随机逼近的在线、无模型的参数整定方法。算法的核心思想是利用高效的同时扰动技术对PID控制器性能指标函数的梯度进行估计,并利用随机逼近技术对PID的三个参数进行在线调整。仿真结果验证了该方法的有效性。     

Tunability and bandwidth of microstrip filters fabricated on magnetized ferrites

The method of moments in the spectral domain is applied to the rigorous full-wave analysis of coupled line microstrip filters fabricated on magnetized ferrites. The results show that the center frequency of the filters can be tuned over a wide range by adjusting the magnitude of the bias magnetic field of the ferrite substrates. However, the filters bandwidth is reduced as the tuning frequency increases. This bandwidth reduction is explained in terms of the behavior of the resonant frequencies and quality factors of the resonators included in the filters.     

Center Frequency Tuning for a Narrowband Superconducting Filter in the Time Domain

This paper presents a mechanical tuning method for tuning the center frequency of a narrowband high-temperature superconducting filter. The filter is designed with 0.5-MHz bandwidth at 166.9 MHz and is fabricated. Tuning is carried out based on the time-domain response of filter return loss. The filter can be precisely tuned to a desired center frequency while maintaining a high-frequency performance. The center frequency is tuned from 167.2 to 166.5 MHz. The tuning range is 0.7 MHz and is sufficient to compensate the frequency offset caused by 0.72% variation in the substrate effective dielectric constant or 4% that of the substrate thickness.      

广义Chebyshev滤波器的优化设计及其快速调试技术研究

文章给出了带传输零点的广义切比雪夫滤波器的分析方法,介绍了优化算法,并讨论了其在滤波器综合设计中的应用,得到耦合矩阵的实际形式。然后对实际微波滤波器的调试技术进行了研究,提出一套人工快速调试方法。最后利用仿真软件建立一个八阶同轴腔滤波器模型并加工调试,实际测试与理论结果吻合较好。     

基于TD-SCDMA的CMOS低通滤波器的设计

这里提出一种基于时分同步码多址技术（TD-SCDMA）的互补金属氧化物半导体（CMOS）滤波器带宽校正方法及校正电路。该方法应用于RS1012芯片（TDSCDMA无线收发芯片）,该芯片采用0.18um射频（RF）COMS工艺。滤波器带宽的调节范围和调节精度在理论和投片中都得到了验证。实现该方法的RC校正电路结构简单,版图面积很小,只有0.04 mm2,电流仅为600 uA。校正电路最大调节范围设计值为＋30%,校正精度为＋2.1%,此测试结果与理论计算是一致的。     

Magnetically tuned klystrons for wide-band frequency modulation applications

This paper describes the application of a ferrite-tunedX-band klystron to produce very wide-band frequency modulation with exceptionally low accompanying power variation. By perturbation techniques, a theoretical analysis of the magnetically tuned klystron is made in terms of the static and dynamic intrinisic properties of the ferrite. The observed operating characteristics show good agreement with the predicted behavior. The design of a practical magnetically tuned X-band klystron for frequency modulation application is discussed in detail. Designs which included a fixed bias field transverse to the tuning field allowed frequency deviation over a 600-Mc bandwidth to be obtained with very good linearity at modulation frequencies below 500 cps. The change in power was less than ± 6 per cent. Another model permitted modulation frequency components up to 50 kc but tuning bandwidth was reduced to 300 Mc.     

基于双光源的可调谐微波光子滤波器

提出了一种基于双光源与双相移光纤光栅(DPS- FBG)的可调谐微波光子滤波器。双光源经过相 位调制后,利用DPS-FBG的反射模式中的两超窄陷波分别对两相位调制光信号的边带进行抑 制,实现相 位调制至强度调制的转换。通过调节两光源的中心波长可以实现单通带与双通带之间的切换 ,实现单通带 的中心频率可调以及3dB带宽可调,实现双通带频率同时可调或者单独可调。建立了理论模 型并进行了数 值分析,最后通过实验进行了验证。实现了滤波器通带的3dB带宽由180MHz增加为319MHz,中心频率从1GHz到7GHz可调。     

Fiber-birefringence tuning technique for an erbium-doped fiber ringlaser

A method of tuning fiber lasers is described and demonstrated. The state of polarization in the fiber is controlled using the strain-induced birefringence of several fiber coils. The fiber laser was tuned over a 33-nm tuning range by rotating a single fiber-coil halfwave plate     

Analysis and Design of Planar Tunable Inner-Coupling Step Impedance Resonator

A full planar tunable band pass resonator is introduced,which is constructed by using novel symmetric step impedance resonator(SIR) and hyperabrupt varactors for wide bandwidth tuning and size reduction.The equivalent circuit model of the proposed resonator is set up.Theoretical analysis based on transmission line as well as odd and even-mode method is completed.The attractiveness of the approach presented lies in its simplicity.Based on the detailed analysis,a 6 GHz to 10 GHz varactor tuned resonator is designed,fabricated,and measured.It shows wideband tuning ability of 37%.The experimental results of the resonator have a good agreement with the analysis results.     

Over 26-nm Wavelength Tunable External Cavity Laser Based on Polymer Waveguide Platforms for WDM Access Networks

We demonstrated a widely tunable hybrid-integrated external cavity laser on a polymer-based waveguide platform. The lasing wavelength was tuned over 26 nm by locally heating the surface-relief-type polymer waveguide Bragg grating fabricated by using the phase mask. The phase-control heater section was inserted between the laser diode and the Bragg grating for the fine wavelength tuning and the stable single-mode lasing. In the 100-GHz-spaced wavelength-division-multiplexing systems, the 1.25-Gb/s directly modulated data streams at each tuned 32 channel were successfully transmitted.