全业务运营业务运营支撑系统建设思路探讨

本文在分析全业务运营的背景下,通过对比国内各运营商业务运营支撑系统建设情况,对中国移动业务运营支撑系统的总体思路、建设策略,与铁通的融合建设等提出自己的理解和建议。     

基于反正切相位检测的Costas环分析及FPGA实现

载波同步是数字无线通信中的一个重要问题,通过对目前QPSK系统中常用的载波同步方法进行比较,在此基础之上介绍了一种基于反正切相位检测的Costas环相干载波提取算法。利用现场可编程门阵列FPGA的可编程性,详细地将此算法模块化,最后在Quartus Ⅱ实现仿真验证。结果表明,该算法载波同步效果良好。随着FPGA的发展,提出的算法对于载波同步环路抖动要求严格的系统具有一定实用价值。     

一种可抵抗RS掩密分析方法的掩密算法

Fridrich提出的RS掩密分析方法,适合于检测采用随机嵌入的LSB掩密算法,不但可以检测信息的存在,还可以检测出嵌入信息的长度。文中对现有的空域LSB掩密算法加以改进,使改进后的算法可以抵抗RS攻击,从而进一步提高了LSB掩密算法的安全性。     

红外仿真中的海面发射率模型

海面作为舰船的主要背景,其红外辐射特性对于舰船红外仿真研究具有重大意义。介绍了三种海面发射率的计算模型：灰体模型、经验模型和理论模型,并针对红外仿真中舰船辐射场和海面背景红外热像模拟两方面的计算要求,分析比较了它们的计算结果。结果显示,对于舰船辐射场计算而言,使用经验模型已经具有足够的精度;而在模拟海面背景红外热像时,在天顶角较大的情况下必须使用理论模型。     

计算全息实现信息相干分解及其在图像加密中的应用

提出一种利用计算全息对信息进行随机相干分解的加密存储方法,它是将须加密图像信息根据相干原理分解成随机的两部分,分别记录在两张计算全息图上.当两张全息图对准合在一起照明再现时,从两张全息图衍射光波的干涉图样中可以再现出原来的信息.只有同时拥有这两张配对的全息图方可解出原来的信息,因而用于图像信息的加密时,具有很高的安全性.     

TD-SCDMA网络中的切换与优化

1TD-SCDMA的切换概述TD-SCDMA（简称TD）系统在继承2G系统硬切换的同时又提出了接力切换的概念,它与传统意义上的硬切换和软切换不同,其设计思想是利用TDD系统特点和上行同步技术,在切换测量期间,利用开环技术进行并保持上行预同步,在切换期间,可以不中断业务数据的传输,从而达到减少切换时间,提高切换成功率,降低切换掉话率的目的（图1）。     

基于近似模型的电子封装散热结构优化设计

针对封装散热结构优化问题中存在的难点,提出了一种基于近似模型和随机模拟的快速全局优化方法.利用Kriging方法建立封装散热结构的近似模型,重构原始的优化问题,采用随机模拟对重构出的目标函数进行寻优,从而得到最优解.采用CVT试验设计,使Kriging模型的泛化预测能力达到最大程度的发挥;在随机模拟中采用Quasi-Monte Carlo法,有效地提高了寻优的效率.以方形扁平封装器件为例,应用该方法实现了封装散热结构的优化,结果表明所提出的方法有效地解决了设计变量中含有离散变量的问题,并且大大提高了随机模拟优化的计算效率.     

Energy-efficient power allocation for NOMA heterogeneous networks with imperfect CSI

In this paper, an optimal user power allocation scheme is proposed to maximize the energy efficiency for downlink non-orthogonal multiple access (NOMA) heterogeneous networks (HetNets). Considering channel estimation errors and inter-user interference under imperfect channel state information (CSI), the energy efficiency optimization problem is formulated, which is non-deterministic polynomial (NP)-hard and non-convex. To cope with this intractable problem, the optimization problem is converted into a convex problem and address it by the Lagrangian dual method. However, it is difficult to obtain closed-form solutions since the variables are coupled with each other. Therefore, a Lagrangian and sub-gradient based algorithm is proposed. In the inner layer loop, optimal powers are derived by the sub-gradient method. In the outer layer loop, optimal Lagrangian dual variables are obtained. Simulation results show that the proposed algorithm can significantly improve energy efficiency compared with traditional power allocation algorithms.     

Bi2SiO5 Doping Concentration Effects on the Electrical Properties of SrBi2Ta2O9 Films

In this paper, we investigated the microstructure and electrical properties of Bi₂SiO₅ (BSO) doped SrBi₂Ta₂O₉ (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 μC/cm² and 138 kV/cm of pure SBT to 1.45 μC/cm² and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.     

Performance analysis and hardware implementation of a nearly optimal buffer management scheme for high‐performance shared‐memory switches

Burst traffic is a common traffic pattern in modern IP networks, and it may lead to the unfairness problem and seriously degrade the performance of switches and routers. From the perspective of switching mechanism, the majority of commercial switches adopt the on‐chip shared‐memory switching architecture, and high‐speed packet buffer with efficient queue management is required to deal with the unfairness and congestion problem. In this paper, the performance of a shared‐private buffer management scheme is analyzed in detail. In the proposed scheme, the total memory space is split into shared area and private area. Each output port has a private memory area that cannot be used by other ports. The shared area is completely shared among all output ports. A theoretical queuing model of the proposed scheme is formulated, and closed‐form formulas for multiple performance parameters are derived. Through the numerical studies, we demonstrate that a nearly optimal buffer partition policy can be obtained by setting an equally small amount of private area for each queue. This work is validated by simulations as well as hardware experiments. Software simulations show that the proposed scheme performs better than existing methods, and packet dropping caused by burst traffic can be significantly reduced. Besides, a prototype of the buffer management module is implemented and evaluated in field programmable gate array platform. The evaluation shows that the proposed scheme can ensure the efficiency and fairness while keeping a high throughput in real workload.