Multiuser beamforming based on max SINR for downlink spatial multiplexing MIMO

In this article, a method based on max signal interference noise ratio (SINR) criterion is proposed, to mitigate the interuser interference for downlink multiuser spatial multiplexing multi-input multi-output (MIMO) systems.Unlike the zero forcing (ZF) scheme in which the SNR is decreased when the interference is eliminated completely, max SINR method makes a compromise between noise and interuser interference.When the number of substreams is larger than the difference between the number of base station antennas and the sum of interference mobile station antennas, the ZF is infeasible.An existing coordinated TX-RX block diagonalization (COOR BD) method uses preprocessing at the receiver to cancel the interuser interference.However, it cannot obtain more receive diversity gain because of the preprocessing.Analysis and simulation show that the max SINR scheme has better performance than the ZF method.Moreover, when the ZF is infeasible, the max SINR scheme can obtain more receive diversity gain than COOR BD in the two-user case.     

Group-based user pairing for virtual MIMO in LTE

A user pairing method is proposed to improve the throughput gain of virtual multiple input multiple output (virtual MIMO) in 3G long-term evolution (LTE).The approach taken in this study separated the user pairing into four steps 1) the users are divided into two groups according to their signal-to-noise ratio (SNR), and different user pairing metrics are proposed for each group; 2) the scheduler chooses a user for transmitting by a given rule; 3) the scheduler searches the pairing candidate for the selected user in each group; 4) the scheduler chooses the final pairing user from the co-group and crossover-group candidates by using a marginal utility function, to balance fairness and efficiency.The method can improve the throughput of users with high SNR, and guarantee fairness for users with low SNR, so it can be used in 3G LTE systems.The article provides both theoretical analysis and simulation results to support the idea.     

射频磁控溅射制备声表面波器件用ZnO薄膜

研究了采用射频磁控溅射法在SiO2/Si衬底上制备ZnO薄膜工艺中溅射功率、氧氩比(V(O2)/V(Ar))及衬底温度对ZnO薄膜结构的影响。利用X-射线衍射(XRD)和扫描力显微镜(AFM)对薄膜进行结构性能分析,表明其结构性能随工艺参数变化的规律。利用优化的工艺条件:射频功率60 W、V(O2)/V(Ar)为0.55和衬底温度350℃,在DLC/Si衬底上制备了ZnO薄膜,制作加工成声表面波滤波器件,测试分析了频率响应特性,中心频率为596.5 MHz。     

固定移动融合的关键问题分析

固定移动融合（FMC）是未来通信网络的发展热点，业界在不断加强相关的研究。但在大规模实施之前，还有若干关键问题需要探讨。采用IP多媒体子系统（IMS）架构提供替代传统应用的实时业务，需解决IP域的服务质量（QoS）问题，统一传统电路域固定、移动用户接入IMS的方式，完成电路域业务流程到IMS的映射；保障IMS承载网络的安全性；转变传统运营模式，建立适应融合需求的新格局。     

Boost ZCT-PWM变换器的改进及仿真分析

针对传统的Boost ZCT-PWM变换器中存在的主开关管硬开通和辅助开关管硬关断的问题,提出一种改进型的Boost ZCT-PWM变换器,使主开关管零电流开通,辅助开关管零电流通断,并且特别适用于IGBT作为开关器件的高电压、大功率应用场合。分析电路的工作原理并用PSpice仿真软件进行仿真研究。仿真结果表明所有开关器件实现了软开关,变换器的效率得到提高。     

皱纹长圆铜波导

微波通信所用的馈线,除要求其具有良好的电气性能外,还要求其可绕、大长度.皱纹长圆铜波导(以下简称长圆波导)不失为一种较好的馈线,为此介绍了此波导的特点、理论分析和设计方法,以及它与常用的椭圆波导、茧形波导之间的差异.此外,长圆波导的另一个用处是作为移动通信的漏泄波导,兼顾传输线和天线的作用.     

机柜转笼的防下沉结构设计

分析了机柜转笼下沉的原因，提出了几种防下沉方法。应用结果表明，这些方法可以解决转笼下沉问题，并可应用到各种转笼式结构的机柜中。     

IP芯核水印技术研究进展

知识产权芯核（IP）水印的核心思想就是将IP模块作为水印载体，通过在其电路设计中隐藏特定的数字标记信息（数字水印），来证明其产权归属或跟踪侵权行为，是一种很有前景的IP保护技术。本文系统地调研了IP水印技术的研究现状，总结了基本研究框架和评估指标，综述和分析了在物理级、结构级、行为级和算法级四个设计抽象层次上IP水印的研究进展，评估比较了几种典型的IP水印方案，探讨了技术难题，展望了下一步的研究工作。     

香港车牌识别算法设计

提出一种香港车牌识别算法.针对香港车牌格式比较自由的特点,算法中通过合并连通域进行车牌定位,通过搜索连通域的所有可能组合进行车牌切分,并采用彩色图像游程邻接算法(CRAG)对彩色图像搜索连通域,使得时间性能大大提高.实验表明,本算法在图像测试集的平均识别率达到95%以上.     

移动自组网中一种新颖的基于概率权重的门限签名方案

提出了一种新颖的基于概率权重的门限签名方案.该方案是数字签名与公钥密码体制的有机集成.它在传统的(n, t)门限签名方案的基础上针对不同安全级别的服务节点设置了不同的签名概率权重.因此,该方案增加了网络的抗攻击能力,在一定的条件下还可以实现入侵检测的功能.