带驻波故障监测功能的AISG塔顶放大器控制单元设计

根据AISG2.0协议对带驻波检测功能的塔顶放大器( TMA)中状态监控、故障告警和数据通信的技术要求,提出了TMA嵌入式控制单元的设计及实现方法。硬件部分首先概述了总体设计方案,然后阐明了OOK( On-Off Keying)模块、可配置式电流告警电路、浪涌电流抑制电路和驻波检测功能的设计思路;软件部分详细介绍了AISG协议栈的设计方法,并给出了低噪声放大器( LNA )及驻波故障的检测流程。测试证明,本系统的电气性能、监控功能以及协议完整性均满足AISG2.0协议的要求,并完成了与主流基站系统厂家的互操作测试。     

塔顶放大器在GSM网络信号覆盖优化中的应用

介绍了塔顶放大器的原理和作用，讨论了这种方案的可行性以及该方案对塔顶放大器的各项技术要求。从广泛的应用结果看，该方案完全可以较低的投入成本达到较好的GSM网络信号覆盖优化效果。     

塔顶放大器在网络优化、射频优化中的作用

GSM网络优化的主要内容包括：网络监测——目的是及时发现并解决可能降低网络服务质量的故障和潜在问题；BSS参数的局部调整；射频优化；系统容量及话务负荷的调整。     

电调天线设备嵌入式AISG协议栈的设计与实现

针对移动通信网络对于远程控制单元(RCU)、塔顶放大器(TMA)等电调天线设备(AND)远程监控要求,讨论了ALD设备嵌入式AISG协议栈的设计与实现方法.开发的AISG协议栈完整实现了AISG2.0要求,保证ALD设备能够与任何符合AISG2.0的电调天线控制系统或基站系统兼容和互操作.协议栈采用层次化、模块化的体系...     

塔顶放大器+基站功率放大器在GSM网络信号覆盖优化中的应用

文章介绍了一种新的GSM网络信号覆盖优化解决方案，分析了这种方案的可行性及其对主要设备的技术要求，并举例说明了该方案对目前GSM网络信号覆盖的改善程度。     

塔顶放大器在LTE网络中的应用分析

LTE网络建设中遇到了一些挑战,包括上下行不平衡、基站天线成本和安装难度大、与3G基站覆盖不同步等。针对这些情况,本文提出了使用塔顶放大器的方案提高基站上行接收灵敏度,从理论上分析了塔顶放大器对于提升覆盖能力的效果,并总结了塔顶放大器在LTE网络建设中的应用场景。     

电调天线设备控制系统的设计与实现

针对提高网络维护和优化效率的需求,开发了电调天线设备控制系统,实现了对诸如RCU、TMA等电调天线设备的远程监测和控制.从系统拓扑结构、主从设备之间通信方式、软件体系结构、系统具体实现方法等方面讨论了电调天线设备控制系统的设计与实现.系统采用层次化的软件体系结构,具有较好的适应性和扩展性;准确完整地实现了AISG2.0...     

爱立信GSM系统中塔顶放大器的使用

本文对塔顶放大器用于爱立信ＧＳＭ 系统提高上行链路质量, 从而改善通信可靠性和语音质量, 扩大小区覆盖面积的作用作了论述, 并对塔顶放大器的类型、是否需要安装等问题作了分析     

应用于无线传感器网络的低噪声放大器设计

给出一种基于SMIC0.13μm RFCMOS工艺、应用于无线传感器网络2.4GHz的低噪声放大器设计。设计目标为在2.43GHz的中心频率下带宽为120MHz,并且增益分为高20dB、中10dB及低0dB三档可调。电路采用功率和噪声优化技术,输入端采用片外电感匹配,输入输出都匹配到50Ω阻抗。在Cadence Spectre仿真环境下的后仿真结果表明:高增益时S21为21.2dB而噪声系数为0.5dB,S11为-29.8dB,S22为-20.7dB。电路在1.2V电源电压下的工作电流约为6mA。     

低Q值匹配网络超宽带低噪声放大器设计

提出了一种基于低Q值匹配网络的超宽带低噪声放大器(LNA)的设计方法。该方法将LC滤波电路加入偏置电路中,以降低系统噪声同时调节匹配网络Q值;通过选择合适的反馈回路,提高LNA的带宽并调节匹配网路Q值;利用匹配电路结构及优化的Q值,解决了放大器频带窄、噪声高、增益低的问题。测试结果表明,在频段1.5 GHz~2.5 GHz内,其纹波特性低于1 dB,增益达到25 dB。将实测结果与仿真结果相比较,验证了该设计方法的合理性,与传统LNA设计方法相比,采用低Q值匹配网络的设计方法结构简单、性能优越,具有广泛的应用价值。     

塔顶放大器在WCDMA系统中的应用

塔顶放大器技术在移动通信中是一项非常实用的技术,可以有效增大系统覆盖范围,提高系统容量,解决基站上行干扰等问题。合理利用塔顶放大器是充分利用资源,提高网络质量,优化网络的良好途径。文章阐述了塔顶放大器的工作原理以及在宽带码分多址（WCDMA）系统中的作用和应用情况。     

用于TMA的平衡式低噪声放大器设计

针对通信基站中塔顶放大器(TMA)的应用,设计了一种应用于TMA的平衡式低噪声放大器,放大器采用平衡式放大器技术和微型3dB混合耦合器,提高了放大器的性能指标,显著减小了电路尺寸,在确定放大器直流工作点后进行输入端和输出端阻抗匹配,给出了版图设计和仿真结果,利用ADS联合仿真功能,得出了一个比原理图仿真更接近实际电路的结果。仿真结果表明在800～1 000MHz的频率范围内,噪声系数不大于1dB,功率增益达到15dB左右,输入输出驻波比小于1.2。     

Design of broadband class-F power amplifier for multiband LTE handsets applications

A broadband class-F power amplifier for multiband LTE handsets applications is developed across 2.3-2.7 GHz. The power amplifier maintains constant fundamental impedance at the output matching circuit which is operating for broadband. The nearly zero of second harmonic impedance and nearly infinity of third harmonic impedance are found for highly efficient class-F PA. The harmonic control circuits are immersed into the broadband output matching for fundamental frequency. For demonstration, the PA is implemented in InGaP/GaAs HBT process, and tested across the frequency range of 2.3-2.7 GHz using a long-term evolution signal. The presented PA delivers good performance of high efficiency and high linearity, which shows that the broadband class-F PA supports the multiband LTE handsets applications.     

On the design of Robust‐WDM local area networks

Robust wavelength division multiplexing (Robust‐WDM) is a proposal to realize cost‐effective WDM local area networks (LANs) which can get around the expensive need for laser wavelength stabilization. The type of these networks that relies on an access protocol with aperiodic reservations and lenient‐token‐passing based control channel (the AR/LTP protocol) is promising. We look at the deployment of the AR/LTP analytical model in designing this type of network. The model is used to predict the effect of component and network parameters on the waiting time characteristics of the network. An increase in node operation times (i.e. receiver response time, transmitter select time and reservation period) would result in increasing the average waiting time of a connection request, but the waiting time is more sensitive to the physical span of the network and its size. It is also observed that increasing the inter‐reservation threshold may result in little increase in waiting time up to some limit beyond which delay increases rapidly. Copyright © 2001 John Wiley & Sons, Ltd.     

Hierarchical content importance-based video quality assessment for HEVC encoded videos transmitted over LTE networks

To improve the accuracy of assessment, many previous works take into account the video content. However, these previous works just only consider the video content, but do not consider the location and importance of the degraded content. Thus, this paper takes into account not only the video content, but also the location and importance of the degraded content, and proposes a hierarchical content importance-based video quality assessment. Firstly, we propose to use the hierarchical content importance-based frame degradation rate (HFDR) metric to quantify the importance of degraded content hierarchically. Secondly, we propose to use the intra random access point (IRAP) loss rate (ILR) metric to quantify the impact of IRAP. Finally, the proposed HFDR metric and ILR metric are subsequently used to develop an objective video quality assessment model. The experimental results show that the predicted mean opinion score (MOS) of the proposed method highly correlates with the actual MOS.     

Technology for extending transmission distance of EPON system

At present, the maximal transmission distance between the optical line terminal (OLT) and opticalnetwork unit (ONU) of an Ethemet passive optical network (EPON) system is 20 km.However, this distance should be extended to 50 km or even longer in some applications such as fiber to the village (FTTV).A method for extending the transmission distance of an EPON system is proposed in this paper, in which the optical power amplifier and the adjustment of dynamic bandwidth allocation (DBA) are the key technologies.     

A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels

A new metric for performance evaluation of transport control protocol(TCP) over wireless channels based on the interference-limited characteristics of code division multiple address(CDMA) system is proposed. According to the new metric, the performance of TCP over CDMA correlated channel for different protocol parameters and different versions is investigated. The results show that appropriate selection of protocol parameters and packet error rate(PER) operation point can improve significantly the capacity of packet-switched CDMA-based network.     

A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels over Interference Wireless Channels

A new metric for performance evaluation of transport control protocol(TCP) overwireless channels based on the interference-limited characteristics of code division multipleaddress(CDMA) system is proposed.According to the new metric,the performance of TCP over CDMAcorrelated channel for different protocol parameters and different versions is investigated.The resultsshow that appropriate selection of protocol parameters and packet error rate(PER) operation point canimprove significantly the capacity of packet-switched CDMA-based network.