Closed-Form Solution of Outage Capacity for Cooperative DF and AF Relay Network

Cooperative relaying permits one or more relays to transmit a signal from the source to the destination, thereby increasing network coverage and spectral efficiency. The performance of cooperative relaying is often measured as outage probability. However, appropriate measure for the channel quality is outage capacity. Although the outage probability for cooperative relaying protocol has been analyzed before, very little research has been addressed for the outage capacity. This paper is the first of its kind to derive a closed-form analytical solution of outage capacity using fixed decode and forward relaying and amplify and forward relaying in independent but non identically distributed (i.n.i.d.) Rayleigh fading channels, considering channel coefficients known to the receiver side. The analytical results show a tradeoff between the SNR and the number of relays for a specific outage capacity. A comparison between decode and forward relaying and amplify and forward relaying shows that decode and forward relaying outperforms amplify and forward relaying for a large number of relays.     

分布式InSAR三维定位的闭合形式解及其精度分析

本文对分布式InSAR(Synthetic Aperture Radar Interferometry)目标三维定位的空间几何关系和工作原理进行了分析,给出了完整的目标定位闭合形式解;对闭合形式解进行灵敏度分析,给出了定位精度指标与系统参数精度指标之间关系的解析表达式;分析表明目标定位几何结构的好坏主要取决于视线矢量、基线矢量和主星速度矢量的空间角位置关系,其中视线、基线平面与视线、速度平面间的二面角是一个关键参数,该二面角越大,几何结构越好.最后在以ENVISAT作为主星、采用"干涉车轮"编队的InSAR系统中,给出了精度指标传递关系的蒙特卡洛仿真验证.     

基于GPRS技术的配电自动化系统通信解决方案

由于配电网点多面广,线路接线复杂且变化频繁,给通信系统的建设带来很大困难. GPRS网络的开通为地理位置分散的电能计量点的监测提供了经济可靠的通信手段.文中对配变监测系统提出了两种不同的网络接入方案.方案一:VPN方式;方案二:APN专网方式.从安全性方面考虑确定APN专网方式接入到GPRS网络作为网络接入方案.     

Closed-Form Expressions for the Current or Charge Distribution on Parallel Strips or Microstrip

Simple but accurate closed-form expressions for the charge and current distributions on parallel-plate stripline or microstrip are given. This form is convenient for use in various applications, such as determining radiation or mode fields of the lines, or frequency dispersion of the fundamental mode of the microstrip. These expressions are used to obtain explicit expressions for the capactitance of these lines, accurate to within one percent of the actual value for any ratio of stripwidth to spacing.     

室内分布系统优化解决方案分析

移动通信室分优化对于提升网络质量和客户感知有着重要的意义。通过对2G/3G共址室分系统存在的覆盖、干扰、外泄、容量、室内外协同、2G/3G互操作等问题进行分析,针对不同问题给出解决方法,并结合西宁室分优化处理经验,提出系统的室分优化解决方案。     

Analytical and Closed-Form Expressions for the Distribution of Path Loss in Hexagonal Cellular Networks

The development of models that predict path loss in a wireless system is worthwhile since they offer valuable information without the need of expensive and time consuming measurements. In the modeling and simulation of cellular systems, a common assumption in path loss calculation is the circular shape of the cells. However, despite its simplicity, this approach has certain drawbacks. This paper proposes an alternative method that considers hexagonal-shaped cells. Exact analytical and approximate closed-form expressions for the path loss statistics are derived. The validity of the circular cell approximation is discussed. Simulated results and comparisons with measurement data in the literature validate the accuracy of the formulation. Finally, we investigate the impact of the size of the cells and the characteristics of the propagation medium on the path loss. The derived expressions simplify the analysis and system-level simulation of wireless networks. Compared to other methods, they give more accurate results in the calculation of path loss when hexagonal-shaped cells are employed.     

数据中心配电系统新型无功补偿解决方案

当前,高频UPS在数据中心的大规模应用带来了供电系统初期功率因数超前的问题,而常规电容无功补偿技术已无法解决该问题。通过对现有主流品牌UPS及典型数据中心和通信机房供电系统的测试情况进行分析,提出了采用SVG动态无功补偿技术解决数据中心供电系统的功率因数超前问题的解决方案。实验验证和现场测试结果显示,该方案解决了数据中心供电系统运行初期的功率因数超前和后期的谐波问题,进一步优化了供电质量,适用于新建数据中心采用。     

室分系统的动态频谱共享方案

动态频谱共享为运营商在室分系统低频段下实现5G NR覆盖层创造了无限可能,同时,室分系统的动态频谱共享还为运营商免去了频谱重耕或购买新频谱许可证的高昂成本,有助于将LTE用户群平稳过渡到5G,并更快推出独立组网模式.探讨了动态频谱共享的背景、部署以及关键技术方案,主要技术方案有MBSFN子帧方案、LTE打孔方案和NR打...     

Approximate Closed-Form Analytical Solution for Minority Carrier Transport in Opaque Heavily Doped Regions Under Illuminated Conditions

An approximate closed-form solution for the transport equations in heavily doped regions is proposed, leading to an expression for the minority carrier currents, in which the influence of technological parameters is easily readable. As an example, the emitter collection efficiency for a photovoltaic device is evaluated in some significant cases     

构建高可用性HIS

随着医院信息系统应用不断向深度和广度的拓展 ,医院对信息系统的依赖程度越来越高 ,要求医院信息系统 7× 2 4小时永不间断地高效可靠运行。计算机集群系统具有高可用性、高可靠性、扩展灵活等特点。介绍了集群系统的基本组成、原理及集群系统的优点 ,通过合理地选择集群系统的软、硬件配置 ,利用集群系统可以构建高可用性医院信息系统。     

基于对象的高可用性系统控制实现机制

高可用性是电信系统的重要特征。文章分析高可用性系统控制的一般特征,并探讨其开发设计过程,进而提出一种基于对象的高可用性系统控制模型的实现机制。     

A Closed-Form Model for Thermionic Trap-Assisted Tunneling

Recently, we proposed a trap-assisted tunneling model (2006) that includes tunneling of thermally activated electrons above the metal Fermi level for explaining the temperature-dependent leakage current in some semiconductor devices. In the present paper, we develop a closed-form version of this model, which provides physical insight by revealing the peak, energy location and spread of emitted electron distribution. The model also yields characteristic field parameters to identify the thermally activated regime of current versus field behavior and the location of peak emission. The closed-form solution of a complicated equation has been achieved using a geometrical interpretation of the integration operation, and by bisecting the range of trap energies, adopting separate approximations for the bisected segments, and then mathematically combining the two segments into a single continuous function valid for the entire range of trap energies. The closed-form model calculations match well with numerical integration results.     

二维零相位FIR数字滤波器设计的闭式最小二乘解

本文二维零相位ＦＩＲ数字滤波器的解析最小二乘设计技术。通过建立频域误差差函数的矩阵形式，并运用与设计问题有关的矩阵的一些性质，得到了滤波器系数的闭式解，使得由给定的频响指标可直接计算滤波器系数，而不必对矩阵进行数值示逆，也不需要基于迭代运算的优化过程。文中给出了滤波器实例，其结果证实了该设计方法的简便性与有效性。     

Reliability and Availability in Reconfigurable Computing: A Basis for a Common Solution

Dynamically reconfigurable SRAM-based field-programmable gate arrays (FPGAs) enable the implementation of reconfigurable computing systems where several applications may be run simultaneously, sharing the available resources according to their own immediate functional requirements. To exclude malfunctioning due to faulty elements, the reliability of all FPGA resources must be guaranteed. Since resource allocation takes place asynchronously, an online structural test scheme is the only way of ensuring reliable system operation. On the other hand, this test scheme should not disturb the operation of the circuit, otherwise availability would be compromised. System performance is also influenced by the efficiency of the management strategies that must be able to dynamically allocate enough resources when requested by each application. As those resources are allocated and later released, many small free resource blocks are created, which are left unused due to performance and routing restrictions. To avoid wasting logic resources, the FPGA logic space must be defragmented regularly. This paper presents a non-intrusive active replication procedure that supports the proposed test methodology and the implementation of defragmentation strategies, assuring both the availability of resources and their perfect working condition, without disturbing system operation.      

高可用度的冗余UPS

简述通信行业标准《通信局(站)电源系统总技术要求》(YD/T1051)对UPS可用度的要求,介绍适用于电信系统的高可用度冗余UPS。     

克州电信低压配电系统改造方案比较及实施

克州电信阿图什市是克州重要通信枢纽,随着新疆通信事业的快速发展,通信业务的不断增加,通信的用电负荷已远远不能满足现有通信发展的需求,急需进行改造扩容。     

Closed-Form Analysis of Various Diversity Techniques for Multiband OFDM UWB System Over Log-Normal Fading Channels

Wireless Personal Communications - In this paper, we investigate the effect of multipath fading on the combined signal-to-noise ratio (SNR) in conjunction with multiband orthogonal frequency...     

雷达系统使用可用度计算机仿真计算

系统可用度是可靠性和维修性的综合反映 ,常用的马尔可夫方法无法给出可修复机电产品的系统可用度计算公式。给出了一种计算双机冷储雷达系统使用可用度的计算机仿真方法示例 ,并可将它推广至一般机电产品的可用度计算。     

System Availability and Optimum Spare Units

The steady-state availability of a repairable system with cold standbys and nonzero replacement time is maximized under constraints of total cost and total weight. Likewise the cost can be minimized under constraints of steady-state availability and total weight. A new, more efficient algorithm is used for the constrained optimization. The problem is formulated as a nonlinear integer programming problem. Since the objective functions are monotone, it is easy to obtain optimal solutions. These new algorithms are natural extensions of the Lawler-Bell algorithm. Availability is adjusted by the number of spares allowed. Other measures of system goodness are considered, viz, failure rate, weight, price, mean repair time, mean repair cost, mean replacement time, and mean replacement cost of a unit.