Limits of compensation in a failed antenna array

In large antenna arrays, the possibility of occurrence of faults in some of the radiating elements cannot be precluded at all times. In such situations, the radiation pattern of the array gets distorted, mostly with an increase in sidelobe level and decrease in gain. Although it is not possible to restore the pattern fully by rearranging the excitations of the functioning elements, compensation methods have been reported in the literature for restoring one performance parameter of the array and making a trade‐off on some other parameter. In this article, we have made a study on the tolerance level of this compensation process. One part of the study deals with the thinning in the failed array, that is, to find a limit on the minimum number of functioning elements of the array that can restore the digital beamforming of the failed array. The second part of study deals with finding the maximum number of element failures that can be compensated. The study was carried out by optimizing the amplitude excitations of the failed array. Instead of classical optimization techniques, particle swarm optimization was used for the compensation process. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:635–645, 2014.     

A simple planar monopole UWB slot antenna with dual independently and reconfigurable band‐notched characteristics

An extremely simple and compact planar monopole ultrawideband (UWB) slot antenna with dual band‐notched characteristics is proposed. The antenna is composed of a circular radiation patch, a microstrip‐fed line, and a partial ground. By etching an arc‐shaped slot on the radiation patch and a C‐like slot on the feed line, dual notched frequency bands at 3.3–3.7 GHz for WiMAX and 5.15–5.825 GHz for WLAN are achieved. And, the two notched bands can be adjusted independently by varying the length of the slots. Moreover, the band‐notched characteristics can be reconfigurable by shorting the corresponding slots. So, the antenna is capable of operating in one of multiple modes which makes it an excellent candidate for UWB applications. Meanwhile, experimental results indicate that the antenna has an available impendence bandwidth from 2.9 to 11 GHz which covers the UWB frequency band, and nearly omnidirectional patterns, stable gains, small group delay in operating band except rejected bands. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:706–712, 2014.     

LTE承载网解决方案研究

分析了LTE的业务特点和承载需求,详细描述了L2VPN＋CE和L2VPN＋L3VPN方案的实现方式,相比于L2VPN＋CE方案,L2VPN＋L3VPN方案在PTN设备上集成简化L3功能实现端到端的IP化LTE承载,具有明显的优势。     

一种面向LTE的GEO卫星通信系统上行时隙同步方案

针对长期演进计划LTE(Long Term Evolution)系统和卫星移动通信系统融合中上行同步存在的问题,提出一种面向LTE的静止轨道GEO(Geosynchronous Orbit)卫星移动通信系统的上行时隙同步方案,并给出与用户传输时延相关的转换时延的计算公式。通过对用户上行时隙数和传输时延差关系的分析,以及对最大等待时延的分析和误码率性能分析,验证了所提出的上行时隙同步方案适用于卫星移动通信系统。     

北京地铁TD-LTE系统的干扰分析

介绍了LTE系统在北京地铁范围内进行系统覆盖时,多系统间干扰问题的分析及计算.本文通过北京地铁这样的特殊场景,结合LTE系统的特点,辅以理论分析及现场测试,分析了在多系统（地铁信号系统、其他运营商等）环境下,在大客流、高速度及系统复杂的地下轨道空间内建设并使用LTE系统的方法.     

基于LTE的BBU集中化组网分析

BBU集中化组网能够有效地提高无线网络资源利用率,加快网络建设速度,降低运营成本,动态地解决无线业务迁移问题。通过分析BBU基带池集中化的技术及其特性,结合网络建设实际应用,提出BBU集中化组网建议。     

天线方向图自动测试系统设计与实现

为了获得一套完整、快速、高效的测试手段和力法,通过对天线方向图测试原理的分析,在微波暗室和测量设备的基础上,基于PNA矢量网络分析仪的测量特性,设计测试力案,使用VC＋＋开发出一套天线力向图测试软件,实现了天线的自动化测试.测试数据符合天线测量要求,在实际应用中为天线方向图自动化测试提供了支撑和帮助.     

基于LTE下行多业务传输QoS保证的跨层调度算法

众多资源分配的调度算法中, 有区别地实现不同业务QoS要求的调度策略研究不多。针对此问题, 通过将不同QoS等级和要求加入到调度策略的影响因素中, 提出了一种适用于LTE下行多业务传输的多目标跨层分组调度算法, 并设计了一个用户满意度函数, 用来评价分组调度算法的综合性能。对该算法性能进行了仿真验证, 并同PF算法仿真结果进行比较与分析, 表明该算法能够满足不同业务的QoS要求, 综合性能优于PF算法。     

浅析LTE规划优化的核心技术

LTE作为目前4G的主要标准,研究LTE规划优化的核心技术,对4G网络的建设和发展具有非常重要的促进作用,本文在LTE概念和架构的基础上,从用户需求、频谱使用效率、新技术规划和与2G、3G共存等方面,分析了LTE规划优化面临的挑战,最后深入的研究了天馈方案、时隙配比和连接状态转换等核心技术,希望能给实际的LTE规划优化,提供一定的参考。     

LTE上行接收分集中一种新的判决反馈检测算法

针对快速时变信道,提出了一种新的联合信道估计和符号判决反馈检测算法应用于LTE上行接收分集.新算法对OFDM数据符号进行硬判决,并利用硬判决结果对该符号上的信道进行估计,估计结果用于相邻数据符号的均衡和解调.分析和仿真结果表明：在高信噪比、快速移动环境下,新算法相对线性插值算法具有较好的性能,而且具有较高的实用性.