NGN若干问题的思考--技术融合是网络融合的基础

本文深入探讨了网络融合和业务融合的理论问题,、论证了三层网络模型;提出了承载层组网功能评价体系;指出了MPLS技术发展的若干方向;比较了电信业务和因特网业务的主要特点,以及由于这些特点不同而对网络的要求的差异;论述了业务连接和网络连接,指出网络连接的重要性.     

A Low-Complexity Precoding Scheme for Downlink Massive MU-MIMO Systems with Low-Resolution DACs

In this paper, we investigate the problem of downlink precoding for the narrowband massive multi-user multiple-input multiple-output (MU-MIMO) system with low-resolution digital-to-analog converters (DACs). We introduce a low-complexity precoding scheme based on the alternating direction method of multipliers (ADMM) framework in this work. An efficient gradient descent (GD) algorithm with adaptive step-size determination mechanism (ASGD) is proposed to alleviate the computational complexity bottleneck of the inherent matrix inversion. Numerical results demonstrate that the ASGD precoder achieves an attractive trade-off between the performance and computational complexity compared with other counterparts.

     

相关向量机软件可靠性建模中失效数据选择

摘要：基于核函数的软件可靠性模型一般对软件失效时间数据与发生在其之前的m次失效时间数据的关系进行建模,着重研究了m取值不同时,其对核函数可靠性模型预测能力的影响。在5个不同类型失效数据集上,采用Mann-Kendall检验观测到m值增大时模型预测能力逐渐下降,说明现时失效时间数据能比较久之前观测的失效时间数据更好地用于预测未来,通过把m的取值划分成几个区间,运用配对T检验进行实验研究,结果表明当m∈｛6,7,8,9,10｝时,模型能够得到最好的预测性能。     

3G无线网络建设问题探讨

移动通信低速语音通信向高速数据通信转变,通信业务由室外向室内转移,无线网络从信号覆盖型向信息容量型演进,网络架构正在发生深刻变革。变革对网络建设、技术和管理提出了新的挑战和要求。针对存在的问题和挑战,提出了相关建议,并介绍了广东联通在技术和管理创新方面的有益尝试。     

3G室内分布系统设计与优化关键问题

首先对3G室内分布系统特点进行介绍,然后对其设计过程中的关键问题进行分析,并给出在后续网络优化过程中的常见问题和相应解决方案。     

Joint optimization of spectrum sensing and accessing in multiuser multiple‐input single‐output cognitive networks

In this paper, a joint spectrum sensing and accessing optimization framework for a multiuser cognitive network is proposed to significantly improve spectrum efficiency. For such a cognitive network, there are two important and limited resources that should be distributed in a comprehensive manner, namely feedback bits and time duration. First, regarding the feedback bits, there are two components: sensing component (used to convey various users' sensing results) and accessing component (used to feedback channel state information). A large sensing component can support more users to perform cooperative sensing, which results in high sensing precision. However, a large accessing component is preferred as well, as it has a direct impact on the performance in the multiuser cognitive network when multi‐antenna technique, such as zero‐forcing beamforming, is utilized. Second, the tradeoff of sensing and accessing duration in a transmission interval needs to be determined, so that the sum transmission rate is optimized while satisfying the interference constraint. In addition, the aforementioned two resources are interrelated and inversive under some conditions. Specifically, sensing time can be saved by utilizing more sensing feedback bits for a given performance objective. Hence, the resources should be allocation in a jointly manner. Based on the joint optimization framework and the intrinsic relationship between the two resources, we propose two joint resource allocation schemes by maximizing the average sum transmission rate in a multiuser multi‐antenna cognitive network. Simulation results show that, by adopting the joint resource allocation schemes, obvious performance gain can be obtained over the traditional fixed strategies.Copyright © 2014 John Wiley & Sons, Ltd.     

以Zn(BTZ)_2∶rubrene为发光层的一种新型白色有机电致发光液晶显示背光源

制备了以Zn(BTZ)2∶rubrene为发光层的5种白色有机电致发光器件,并将其应用于液晶显示背光源。5种器件色度最好时的CIE坐标值为(0.32,0.33),最大有效发光面积达到3 cm×3 cm,此时器件的平均亮度达到264 cd/m2,亮度均匀性达到80%。并且分析了随器件有效发光面积增大,发光均匀性、亮度以及最大量子效率减小而器件电流密度反而增大的原因。同时发现附加金属(Ag)辅助电极在一定程度上有助于提高器件的性能。最后将所制备的5种器件与液晶显示屏相匹配,它们均基本满足液晶显示对背光源的要求。     

CRN中基于公平性的数据采集算法研究

研究了认知无线电网络的分布式数据采集问题.首先讨论了SU的合适载波侦听范围(PCR).以此PCR为基础,一个SU可以成功地发送数据且不对PU和其他SU造成干扰.然后,提出了一种兼顾公平性的异步分布式数据采集(ADDC)算法.ADDC算法以分布式策略把快照数据收集到基站,且没有任何时间同步要求.与集中式和同步式算法相比,ADDC算法的可拓展性和实用性更强.全面的仿真实验结果表明,ADDC算法的数据采集效率更高,数据采集时延更低.     

双速度环在双马达直流调速系统中的应用

在雷达控制系统中,双速度环驱动系统应用于工程设计和产品中还为数不多,但实践已证明了他的可行性和独特的优越性。尤其在多马达驱动系统中,使用多速度环控制体制,可以使驱动系统的设计更简洁,生产、调试更方便,运用更灵活。从工程实际应用出发,提出了双马达直流驱动系统采用双速度环体制的必要性,进而对这种工作体制的特点,可能出现的问题及解决办法进行了分析和论述。     

定向含能动能杆战斗部对TBM毁伤概率分析

为准确计算定向含能动能杆战斗部对战术弹道导弹(TBM)的毁伤概率,完成战斗部作战效能评估,文中在分析传统毁伤概率计算方法误差率大、精确率较低的基础上,把动能杆的毁伤能量分为冲击波产生的能量、杆条剩余动能和含能材料化学能,建立基于能量比的毁伤概率计算模型.以假定条件下的M39导弹为TBM目标进行计算,结果验证了模型的合理性与可信性,为毁伤概率计算提供了一种方法和技术手段.