FDD-LTE技术和规划设计方法研究

FDD-LTE是目前4G网络的核心技术,但在实际运营过程中,FDD-LTE技术遇到了较多的瓶颈和制约,其低运营成本高网络效率的特点并没有完全发挥出来。文章通过分析,找到了FDD-LTE网络规划设计中的一些策略和方法,认为FDD-LTE遇到的局限性是技术更迭过程中的必经阶段,目前的技术问题可以随着技术改进过程逐渐克服。     

关于FDD-LTE网络规划覆盖探讨

主要研究FDD-LTE网络规划覆盖问题,对LTE系统结构以及运行原理进行了简单分析,并从统一规划、运营规划两方面对LTE网络规划进行了研究,还从应用场景、覆盖范围和容量估算以及站点布置等方面对LTE网络覆盖问题进行了研究。     

电子对抗及其设备

0310246TD-SCDMA 相邻小区下行链路干扰分析与仿真[刊]/李少斌//重庆邮电学院学报(自然科学版).—2002,14(4).—15～18(K)主要研究了 TD-SCDMA 系统中相邻小区间下行链路的干扰,给出小区间下行干扰模型和传播损耗模型,并通过仿真得到不同时隙、不同小区业务负荷条件下来自相邻小区的下行链路干扰数值变化曲线。对小区间干扰的分析和仿真为优化未来网络的容量以及性能提供了有价值的参考。参5     

PHS系统在同频干扰下的网络容量分析

出于网络优化的目的,在对PHS网络进行频率规划的前提下,分析了同频干扰对于PHS系统容量的影响,得出了PHS网络在干扰容限的限制下最小小区半径随传播条件的波动范围。通过自己搭建的PHS系统仿真平台进行了仿真验证,证明了理论分析与仿真结果的一致性,并且估算了在此结果上的PHS网络Erlang容量,提出了一些建议。     

TD-LTE与TD-SCDMA邻频干扰的分析

分析了2.35 GHz频段的TD-LTE与TD-SCDMA系统宏小区干扰时的性能损耗,建立了基于Monte Carlo仿真方法的系统模型,给出了3个干扰场景下的仿真结果。通过改进ACIR模型和干扰 算法模型,进而保证网络质量,使得系统容量最大化,令仿真结果科学可信,使之适合分析 TD-LTE与TD-SCDMA系统的共存问题。通过分析地理位置偏移、带宽和功率控制参数对共存系 统性能损耗的影响,得出不同参数设置对TD-LTE与TD-SCDMA系统共存时的影响,给出两系统 共存时ACIR建议值。研究结果为异系统混合组网及网络优化提供了参考依据。     

贵阳公共交通网络上级联失效的研究

级联失效是研究复杂网络的一个重要分支,如何应对级联失效所引起的大规模故障一直是网络科学的重要课题之一。首先,简要地介绍了复杂网络上级联失效的负荷-容量模型。最后,基于负荷-容量模型,对贵阳市公交停靠站点网络的一部分上的级联失效进行了仿真分析。结果表明,随着容许系数α增大,该网络的鲁棒性有了较明显的提高。     

干扰消除技术在CDMA网络中的应用

CDMA网络中存在前反向的多址干扰,降低了前反向容量。为了减少多址干扰对前反向容量的影响,对多址干扰产生的原因和机理进行深入分析,详细介绍了多用户检测技术和干扰消除技术。通过对造成干扰的所有用户信号信息进行检测,根据多址干扰信号的结构特征进行干扰消除和信号恢复,从而改善各个信号的信噪比,提高CDMA系统的前反向容量。重点介绍了准线性干扰消除技术QLIC（Quasi-Linear Interference Cancellation）和反向干扰消除技术RLIC（Reverse Link Interference Cancellation）的基本原理,分别对QLIC技术和RLIC技术的容量增益进行了理论推导,并计算了QLIC和RLIC对CDMA网络容量提升的程度。QLIC和RLIC是现有CDMA网络容量提升的重要技术手段,能够为运营商进行技术升级和网络部署提供重要参考。     

基于随机几何理论的中继OFDM系统容量分析

该文将随机几何理论应用于特定的基于译码转发(DF)中继的OFDM系统中,通过推导分析建立基于随机几何理论的中继OFDM系统容量模型。文中假设用户在环域范围内服从随机均匀分布,同时假设接入域用户之间存在频率复用,通过在考虑接入中继链路对接入基站链路的共道干扰时,以干扰积分上限值替代实际干扰值等理论分析,在中继和基站节点功率受限的情况下,得到完整的系统闭合容量表达式模型。并通过仿真对基于容量模型的系统传输速率值与理论值进行了比较,仿真结果证实了该文所建立的容量模型的合理性。     

校园高话务区FDD-LTE覆盖方式分析

分析了运营商关注的话务高度聚集区——高校学生宿舍区的FDD-LTE覆盖组网的类型、覆盖和容量特征、相互配合关系以及类型选择的分析方法、步骤,提出了2层组网的目标。最后,对可以运用的各种特色覆盖方式进行了介绍和对比,有利于运营商提前应对未来可能出现的网络负荷瓶颈。     

Lutz信道模型下卫星CDMA系统的容量分析

针对CDMA卫星系统,详细分析了卫星对地多波束模型中用户受到的多址干扰,仿真得到了理想功控下卫星接收端信号的信干比与单波束容量的关系。在非理想功控条件下,针对阴影衰落和多径衰落对信号功率的影响进行了详细的理论分析和数学推导,独立于编码调制方式,从功率角度着重分析了Lutz信道模型下的卫星容量计算方法,增加了计算模型的普适性。最后仿真得到Lutz信道模型下卫星接收端的最低解调门限与单波束容量的关系。通过对比,得出了复杂信道下卫星实际容量与理论容量的偏差,为卫星波束设计、功率分配等问题提供了参考。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.