如何有效利用HFC上行信道

在HFC(Hybrid Fiber Coax)宽带网络中,传统的上下行非对称带宽分配方法并不能有效地支持快速双向多媒体业务.首先对上行传送时延进行了分析,然后提出并讨论了一种通过分割DS(数据时隙)、增加捎带请求以减少冲突的方法,使上行信道得到更为有效的利用.     

深圳河潮汐模型生潮设备与数据自动采集系统

 为配合深圳河潮汐模型试验，采用直流脉宽调速技术对其生潮设备进行了研制。控制软件采用模糊控制法编写，并就模糊控制方法描述了模糊控制器的构造特点和模糊推理准则。数据采集系统全部由计算机自动控制，并设计了良好的人机界面。经过数月的试验，表明整个系统精确可靠，稳定性好，能满足试验要求。     

基于IEEE 802.16e的跨层上行调度架构设计

对IEEE 802.16标准的上行链路调度架构进行了研究,并联合MAC层和物理层,设计了一种跨层的上行调度结构,在满足移动性要求的同时增强了系统的QoS保障能力,使频谱利用率和吞吐量得到提高.     

信息网络战新趋势研究

随着信息和网络技术的飞速发展,信息网络战的发展趋势及作战形式成为军事界热门话题.新时期的信息网络战已经成为一种优先被考虑的,贯穿战争整个过程的,破坏性极大的“顶级”作战形式,它的成败将直接关系到国家的安危与存亡.文章通过对最近几年信息网络战经典案例研究,总结分析了其所呈现出的新趋势,并为军队适应信息网络战的发展变化提出了几点建议.     

相干光检测系统中的偏振控制

相干光检测可以提高光通信系统的接收灵敏度,改善系统的性能;但大气的退偏效应使光信号通过大气传输后偏振状态随机变化,难以实现两束光偏振态一致的要求,直接影响该系统的检测效率。文中讨论了相干光通信系统偏振控制的新方法,在此基础上建立了偏振控制数学模型。选择挤压光纤偏振控制器作为该方案的偏振控制器件,选择模拟退火算法为该系统控制算法,并利用改进后的模拟退火算法实现偏振态的自动控制,整个控制过程采用盲搜索,没有具体参量的变化。仿真结果表明:该方法适合相干光通信,达到了偏振控制的目的。     

Prediction of the impact of substrate coupled switching noise on frequency synthesizers

This paper proposes a methodology to accurately predict the phase noise effects in frequency synthesizers as a consequence of switching noise coupled through the substrate. The method proposed is based on a phase model of a frequency synthesizer where each circuit block is characterized by complex noise sensitivity functions. Considering the phase information of the different contributors allows to evaluate the noise without overestimation, as well as identifying the main noise contributors. This information can then be used by designers to decide where to put the effort to mitigate the noise effects. The methodology is applied to a typical N-Integer frequency synthesizer based on a LC-VCO. Measurements on this frequency synthesizer implemented in a 0.35 μm CMOS technology have provided information of the relative importance of the noise aggressors, the effect of the loop on the phase noise, as well as comparison to the predictions obtained with the proposed methodology.     

ODF工艺中边框胶穿刺的影响因素研究

根据ODF(OneDropFilling)工艺的实际生产情况,探讨了液晶量、边框胶涂布效果、关键工艺生产节拍(TactTime)和外围边框胶(DummySeal)设计方式对边框胶穿刺情况的影响,发现ODF工艺中液晶与未固化的边框胶接触是发生边框胶穿刺的根本原因。液晶量越大边框胶穿刺情况越严重;边框胶涂布效果的直线性越好,其穿刺情况越轻微;液晶与未固化边框胶的接触时间越长,其穿刺情况越严重,甚至出现大量漏液晶;外围边框胶开口式设计有利于改善边框胶穿刺情况。     

基于FPGA的移动通信中卷积码编码器设计

卷积码是一种性能优良的差错控制编码。介绍了卷积码编码原理,基于FPGA利用VHDL硬件描述语言实现了一个（2,1,9）卷积码编码器。给出了仿真结果,并在FPGA器件上验证实现。仿真及测试结果表明,达到了预期的设计要求,并用于实际项目中。     

Performance Analysis of Multiuser Diversity in MIMO Systems with Antenna Selection

In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent 'virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems.     

电子元件老化筛选设备在线检测技术研究

为解决传统电子元件老化筛选设备在线检测技术检测误差高的问题,设计一种新型电子元件老化筛选设备在线检测技术.通过切换老化筛选设备电路模拟信号,采集电子元件老化筛选设备相关数据,以滤波器截止频率为标准,执行在线时钟配置,计算老化筛选设备在线检测数据误差,在低于0.04％的情况下,将电子元件老化筛选设备相关数据存储至SD卡中...