A low-complexity 3-D geometric model for the description of CCI in cellular systems

In this paper, we propose a three-dimensional geometrically based stochastic model for the study of co-channel interference in cellular mobile systems. Exact analytical expressions for the statistics of the angle-of-arrival (AoA) of the interfering signals at the base station and the outage performance of a cellular network are derived. Simulated results show the merits of our proposal compared to the two-dimensional approach. The uplink AoA distribution statistics are examined in relation to cell size, antennas’ height and frequency reuse factor. Furthermore, the impact of base station antenna radiation pattern, beam tilting and cell sectorization on system performance is investigated.     

基于多目标粒子群算法的变电站5G天线布点

为了减轻5G基站天线引入变电站后对站内敏感设备带来的电磁干扰，并对站内各监测设备处的5G信号进行优化，提出了一种基于多目标粒子群算法的变电站5G基站天线布点方法，即以变电站敏感设备处的射频场强不能超过规定的电磁兼容抗扰度限值为约束条件，以站内监测设备接受信号的Pareto最优解作为目标函数，采用多目标粒子群算法在变电站相关布点区域内寻找出最合适的基站天线布点。以500 kV官渡变电站为例，按照其内部实际的空间布局，利用本文算法得到4种天线布点安装方案，都能使得站内所有敏感设备处的射频场强低于10 V/m抗扰度限值，同时还能使得站内各监测设备处的平均信号分别提升3.77、6.37、4.34、4.58 dB,监测设备信号的方差分别减少了15.07%,12.64%,14.62%,14.78%,说明了本文算法即可以在一定程度上提升监测设备处的信号强度，还能使得站内各监测设备处信号的离散程度减小，使得信号在监测设备处覆盖更稳定，能为实际工程中变电站内5G基站天线的布点提供一定的参考。     

京汉微波河南段搬迁工程电路解决方案

以京汉微波河南段省调—薛店站之间微波天线路由被阻挡为例,分析了建立省调站—许昌站临时迂回路由来实现京汉微波电路转移的过程,介绍了微波设备搬迁前和搬迁后电路的运行状况,阐述了搬迁后省调端网管以及监控的解决方案。     

距离约束算法在微波天线面形测量中的应用

微波天线的工作面的加工精度直接影响其工作性能,因此,对加工后的工作面进行高精度的面形测量是必要的.一种新的基于距离相对约束的视觉测量方法被用于微波天线面形的高精度测量,测量程序可分为两步:直接线性变换求初值和基于距离约束的最优化解算,解算过程中完成了透镜畸变的校正,其相对精度可达1/2,000,并用最小二乘法拟合了微波天线的面形.     

Digitized RF transmission over fiber

With rapid growth in demand for broadband wireless and wired connectivity, a unified communication backbone network that seamlessly integrates the backhaul network of wireless broadband access networks with existing optical access network infrastructure can offer significant benefits to network operators through consolidation of network infrastructure. Direct transmission of microwave signals at radio frequencies over optical fiber (radio-over-fiber) has long been considered as a method for simplifying base-station architecture in antenna remoting applications where antenna base stations are located far away from a central processing unit [1], [2]. In such applications, multiple antenna base stations are normally connected via a backhaul or feeder network to a central office that performs key network functions such as switching and routing.     

Safety standards for human exposure to radio frequency radiation and their biological rationale

Exposure guidelines for RF radiation have been promulgated for nearly half a century. However, our understanding of biological effects of exposure to RF radiation is still evolving and more so for cellular mobile telephones and wireless personal communication devices. There are two different sets of guidelines promulgated for limiting human exposure to RF radiation, worldwide. Currently, there is a backdrop of persistent, publicly expressed lack of confidence in radio-frequency (RF) exposure standards, pertaining to the maximum permissible exposure (MPE) level of humans exposed to RF electromagnetic radiation. Much of the current effort is driven by the advent of cellular mobile telephony, which uses RF radiation in the range of 800-2,500 MHz. The setting of guidelines or standards for maximum permissible levels of exposure to RF and microwave radiation is a valid approach to managing the risk of such exposures. The existing guidelines, however, are based on results obtained from acute, short-term studies that are atypical of the RF exposures associated with the handset of cellular mobile telephones. For the first time in human history, a source of RF radiation is located right next to the head of millions of cellular mobile telephone users. Biological effects after repeated, prolonged, or lifelong exposure to RF energy emitted by these low-power wireless telecommunication devices have been investigated only during the past few years. The existing scientific results are equivocal and arguable in many respects. Consequently, there remains a widespread public concern about the adequacy of existing guidelines in safeguarding the general population against possible harm of RF radiation from cellular mobile telephones.     

考虑建筑物遮蔽的电力应急通信基站选址双层优化方法

电力应急通信基站仅依靠人的主观经验部署存在不足。因此,考虑建筑物对基站信号的遮蔽影响,基于单兵前往灾区勘测的回传信息,对研究问题进行图形化描述。在此基础上,提出了电力应急通信基站选址的双层优化模型。上层以基站间信号传输损耗最小为目标,在划定的基站可选位置范围内,针对非线性模型,利用粒子群算法优化基站的预选位置。下层以基站间信号传输路径与建筑物的间隔距离最大为目标,利用支持向量机优化基站的最终位置,并传递回上层以计算信号传输损耗,通过迭代优化获得基站的最优部署位置。通过在算例中与单层模型比较,验证了所提方法的可行性与有效性,可为发生重大自然灾害后电力应急通信网的搭建提供技术参考。     

基于LS码的分布式MIMO-CDMA系统研究

研究了基于LS码的分布式MIMO-CDMA系统结构,提出了广义的分布式MIMO系统的信道模型,给出了采用MIMO技术时发射机和接收机的结构.最后以单小区双天线的三基站收发端分布式网络为例,仿真了不同的扩频序列、基站收发端的数目和多天线与系统性能的相互关系.结果表明使用LS码扩频的分布式MIMO-CDMA系统性能比使用Walsh码扩频的MIMO-CDMA系统性能优越,基站收发端或移动台采用多天线时的性能优于单天线.     

海事FBB站典型故障排查与分析

海事FBB站主要承担岸船数据传输以及应急通信任务，针对某船载海事FBB站开机后天线无法启动跟踪目标卫星故障，从设备组成和工作原理等方面出发，详细说明了故障排查的步骤。通过梳理系统自检报告和系统启动流程，测试分析各模块输出信号，定位了故障芯片。对比历史数据，分析了设备工作环境、震动、遮挡等外部因素对天线工作的影响，总结出通过温湿度控制、防氧化处理，以及编写海事监控系统爬虫软件等预防性检修维护设备方法，对同类型设备故障的分析排查有着极为重要借鉴指导价值。     

Printed dual-band base station antenna for GSM/DCS/PCS/UMTS and LTE applications with dual polarization

A new design of the dual-band and dual-polarized base station antennas for supporting the mobile communication systems operating at the GSM/DCS/PCS/UMTS and LTE frequency bands is presented. A wide input impedance matching bandwidth is achieved due to a trident-shaped feeding technique. Two printed dipoles, which are located perpendicularly to each other and fed by stepped-microstrip lines, establish the proposed antenna. In addition, by locating a low-profile cavity-backed structure, as a metal reflector under the antenna, bidirectional radiations of the dipoles are switched to unidirectional radiations with an increase in the gain of the antenna. Measurement results indicate that the proposed antenna is suitable for base station applications at the operating frequencies of 800/900/1800/1900/2300 MHz. The isolation is better than 20 dB, and peak gains of 10.08 and 9.96 dBi are attained at port-1 and port-2, respectively. Furthermore, the HPBWs of the antenna in H-plane is more than 61° for each port. The overall dimension of the antenna is 168 × 168 mm², which is mounted upon a 222 × 222 mm² cavity-backed structure with a depth of 42 mm.     

On the base stations antenna system design for mobile communications

The design of a base station antenna for mobile communications is presented. The orthogonal method (OM) is applied under constraints on nulls of the radiation pattern. In the synthesis process the mutual coupling between the elements of the antenna array could be taken into account. Beam tilting and direction of arrival are also considered. The whole design is completed by implementing a special architecture of the antenna. Finally, some examples show the applicability of our technique.     

具有固定中继节点多跳小区结构

为了在低发射功率的前提下扩展蜂窝小区的覆盖范围,本文基于多跳通信模式,提出由中心基站负责固定中继节点接入,移动节点通过固定中继节点的多跳中继而连接基站的网络结构,即接入式多跳小区结构.此结构提供了在低成本条件下完成区域覆盖的方法.对该小区结构的覆盖特性进行了分析,结果显示具有3个或4个固定中继节点的多跳小区结构可以有效地实现基站覆盖范围的扩展.     

Reviewing the RF safety issue in cellular telephones

Sources of RF radiation in the human environment continue to proliferate. New applications of RF energy in telecommunications are being developed at an astonishing rate. As for other RF-emitting devices, concerns have been raised as to the safety of cellular telephones. Cellular telephone base station emissions have been measured and found to be below exposure standards developed by the NCRP and the ANSI. In some cases, handheld and portable units may generate dose rates which approach the NCRP and ANSI standards for localized SARs. RF radiation standard development has been ongoing for over 50 years and substantial information has accumulated regarding RF energy absorption in man. This growing knowledge is reflected in the recent revision to the ANSI RF radiation exposure standard, which emphasizes the dynamic nature of such standards. Continued research on RF health hazards are being led by federal agencies and industry. Thus far, no supportable evidence has been brought forth to show that exposure to non-ionizing radiation from cellular telephones causes adverse health effects     

吉林移动室内覆盖供电保障系统的建设及效果分析

随着移动通信业务的快速发展,对写字楼、酒店、商场、超市等人口稠密场所进行信号覆盖或加强(覆热、覆忙)的窒内微峰窝基站逐渐成为移动运营商保障的一个重点。近年来,由于国内电力紧张,城市用电量大,供电线路老旧,经常出现事故性或让电等电力中断,导致微蜂窝断站,因此迫切需要对室内覆盖微蜂窝系统建设供电保障设施。本文着重介绍了室内覆盖系统的供电现状、各场景的基站应用的布置、断电及分布等情况,探讨了在室内覆盖系统应用壁挂式UPS、一体化户外直流电源等交直流供电的不同解决方案,对使用效果进行了理论计算,并通过各方案在吉林移动各地、市的应用做出了实际使用效果分析。     

Mobile Phones: Bad for Your Health?

Mobile phones use electromagnetic fields to establish a wireless communication link to the nearest base station. When someone speaks on a mobile phone, that phone is sending out electromagnetic waves (EM). When someone listens on a mobile phone, that phone is capturing electromagnetic waves. Electromagnetic waves go out and come into a mobile phone through its antenna. That antenna is located very close to the user's head, and people have naturally wondered about the health effects of radiation from mobile phones since their inception.     

移动通信室内覆盖供电保障系统的建设及效果分析

近年来,由于国内电力紧张,城市用电量大,供电线路老化,经常出现事故性或断电等电力中断,导致微蜂窝断站。因此,迫切需要对室内覆盖微蜂窝系统建立供电保障设施。着重介绍了室内覆盖系统的供电现状,各场景的基站应用的布置,断电及分布等情况,探讨了在室内覆盖系统应用壁挂式UPS,一体化户外直流电源等交直流供电的不同解决方案,对使用效果进行了理论计算,并通过各方案在吉林移动各地市的应用做出了实际使用效果分析。     

SDH数字微波天馈线系统维护的分析

介绍天馈线系统的常见故障检修经验、故障处理方法以及日常维护和保养。结合京汉微波安阳—临漳站微波天线调整,阐述SDH数字微波天馈线系统检修方法。此外,还指出如果将天馈线系统纳入监控管理,可以提高天馈线维护质量和效率。     

X波段圆极化天线的设计与实验

介绍了一种圆极化宽带圆锥喇叭天线,用于地检设备子系统中。天线的圆极化性能是通过金属螺钉在圆波导的管壁对称地插入,等间隔排列来实现的,螺钉直径与插入深度由计算得出。为实现信号低反射馈入,馈电端口采用了矩一圆波导转换器,完成了从矩形波导过渡到圆形波导。天线的辐射器采用了传统的圆锥喇叭。使用CST微波工作室。仿真该天线,并调整各部分的尺寸,使得天线性能最优化。实验测量数据与仿真结果吻合较好,在400MHz的工作带宽内,天线增益大于14．5dB,增益平坦度好,轴比小于1．5dB,驻波比小于1．2。     

点聚焦透镜天线及分辨率的分析与测量

本文分析了点聚焦透镜天线的一些基本特性,采用波动理论方法分析了电磁波经透镜会聚的焦斑的大小和横向空间分辨率,指出点聚焦透镜天线在会聚点的天线特性与相同场分布的平面口径天线在无穷远处的天线特性的关系,提出了透镜天线的分辨率的一种测量方法和使用条件.通过实测,测量结果和理论较为吻合.     

Bloelectromagnetics Research Activities in Europe [Health Effects]

A recent report issued by EMF-NET offers a lengthy list of European projects on the biological effects of power line and wireless communication electromagnetic fields. The list also includes projects on potential risks related to exposure in the working environment. The EMF-NET project is an initiative of the EC and is titled "Effects of the exposure to electromagnetic fields: from science to public health and safer workplace." This four-year project, which is to conclude in 2008, is one of the most ambitious and all-encompassing programs funded by the EC to date. It targets exposures from a wide range of nonionizing electromagnetic-energy-emitting devices, sources, and systems - including power lines, cellular mobile phones, base stations, broadcasting antennas, and household electrical appliances such as mixers and induction ovens (IH hobs) - as well as various electromagnetic equipment found in industry environments and health care facilities