地面数字电视单频网同频干扰分析

以广电总局推荐的地面数字电视工作模式5为理论基础,首先理论分析了影响地面数字单频网内产生同频干扰现象的技术参数;其次通过仿真规划软件调整相关技术参数,同时观察单频网内同频干扰区域分布情况并总结规律;最后根据已知技术参数对干扰区域的影响,尝试提出消除覆盖区域内同频干扰现象的优化方案,并通过仿真规划软件进行模拟.     

巴音郭楞电视台地面数字电视单频网建设

本文简述了在边疆少数民族地区组建地面数字电视单频网过程中的一些措施和解决方案,从单频网的突出优点、组网特点等环节详细介绍在组网过程中避免同频干扰的措施.     

数字电视接收机中降低同频干扰的方法

提出一种数字电视接收机中消除模拟同频干扰的解决方案.经过实验室测试和现场路测证明,该设计结构与均衡器结合,在采用16QAM时,可降低9 dB的同频干扰,采用4QAM时,可降低14 dB的同频干扰.     

国标地面数字电视单频网的组网与建设

在研究国内相关标准、技术的基础上,主要对地面数字电视单频网组网中涉及的关键技术单频网组网的同频干扰与建站距离等问题进行分析和阐述,并开发了采用两种机制的网络管理系统软件,解决了单频网组网过程中相关设备远程管理的问题。同时,介绍了山西省国标地面数字电视单频网的建设情况。     

单频网和同频转发器在常州地面数字电视平台建设中的应用

地面数字电视作为一个新兴媒体,充满着巨大的潜力和生机.本文介绍了常州地面数字电视的发展概况,建设了公交车和楼宇两个平台,着重介绍了地面数字电视平台建设中信号覆盖的两种方案——单频网和同频转发室内覆盖.     

无锡地面数字电视覆盖与同频干扰分析和测试

介绍了无锡DS-33频道地面数字电视的覆盖规划过程,通过理论计算和覆盖仿真,详细分析广电大厦发射点、二茅峰发射点的覆盖效果以及对周边城市同频道模拟电视信号的干扰情况,并由实际测试结果验证规划的可行性,为其他城市的地面数字电视覆盖规划提供参考。     

江都地面数字电视单频网的实施

本文根据江苏省中央广播电视节目覆盖工程项目建设总体技术方案,介绍了扬州市单频网DS-37频道江都站点前端系统、发射系统的构建,提出了地面数字电视后期发展的一些想法。     

国标双模数字电视PAL同频干扰消除算法研究

提出了一种针对国标双模数字电视接收机的PAL制模拟电视同频干扰(CCI)消除方案.利用PAL制模拟电视信号能量主要集中在亮度、色彩和声音载波,且相对位置已知,可以在亮度载波段进行CCI是否存在的检测,若存在,则在三干扰频段内消除CCI.该方案极大地降低了算法复杂度和硬件开销.仿真结果表明:AWGN信道,多载波模式下.有CCI消除比无CCI消除有1～2dB的增益;单载波模式下,加CCI限幅消除后,系统性能有了很大提高,且当CIR减小到-3.5 dB时,可达到TOV点(BER=3×10<'-6>).     

数字电视同频转发器在无锡地面数字电视中的应用

本文简要介绍了数字同频转发器的原理,根据无锡地面数字电视覆盖的现状,就东亭弱信号区的补点进行了设计、规划与实施,最后进行了测试,达到了预期覆盖补点的目的.     

地面数字电视单频网系统分级建设研究

伴随着全国地面数字电视700兆赫频率迁移工程的展开,未来我国地面数字电视将会构建众多单频网系统.现阶段地面数字电视发射台站的建设要求比较明确,而围绕单频网的系统建设相对薄弱,需要进行顶层设计、统一构建.本文从系统建设和台站建设两个层面分别进行了探讨,根据四种单频网类型提出了三种单频网系统级别,并对每种级别的单频网系统建...     

Improved Analysis of Co-Channel Interference in Cellular Communications Systems

1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis…     

Cell-Site Diversity Against Co-Channel Interference in LMDS Networks

LMDS networks are fixed radio systems providing advanced telecommunication services to a variety of users. Millimeter wave frequencies above 20 GHz have been allocated to LMDS systems by ITU-R and CEPT. The design of LMDS systems must take into account how interference affects performance considering the dominant propagation impairments in these frequencies. In the present paper, cell-site diversity, an effective fade mitigation countermeasure for LMDS systems, is considered for the reduction of intersystem interference on downstream LMDS channels. The intersystem cochannel interference may originate from adjacent LMDS networks or from point-to-point links operating at the same frequencies. A physical propagation model for the calculation of carrier-to-interference ratio diversity gain for the downstream channel is presented. Numerical results focus on the impact of frequency of operation, the subscriber's service availability and the climatic conditions on the interference analysis of LMDS networks either using or not cell site diversity. Athanasios D. Panagopoulos was born in Athens, Greece on January 26, 1975. He received the Diploma Degree in Electrical and Computer Engineering (summa cum laude) and the Dr. Engineering Degree from National Technical University of Athens (NTUA) in July 1997 and inAprilxcan l 2002. From May 2002 to July 2003, he had served the Technical Corps of Hellenic Army. In September 2003, he joined School of Pedagogical and Technological Education, as Assistant Professor. He is also Research Assistant in the Wireless & Satellite Communications Group of NTUA. He has published more than eighty papers in international journals and conference proceedings. He is the recipient of URSI General AssemblyYoung ScientistAward in 2002 and 2005 respectively. His research interests include radio communication systems design, wireless and satellite communications networks and the propagation effects on multiple access systems and on communication protocols. He is member of IEEE and member of Technical Chamber of Greece. Konstantinos P. Liolis was born in Athens, Greece in 1981. He received the Diploma degree in electrical and computer engineering from the National Technical University of Athens (NTUA) and the M.Sc. degree in electrical engineering from the University of California, San Diego (UCSD) in July 2004 and December 2005, respectively. He is currently working towards his Ph.D. degree in electrical engineering at NTUA. From September 2004 to December 2005, he was research assistant in the California Institute for Telecommunications and Information Technology (Cal-IT2) within UCSD. Since June 2006, he has been with the European Space Agency Research and Technology Centre (ESA/ESTEC), Noordwijk, The Netherlands. His research interests are in the areas of multiple antenna (MIMO) and multicarrier (OFDM) transmission techniques and their application to broadband fixed wireless access and satellite communication networks. He is student member of the IEEE and member of the Technical Chamber of Greece (TEE). He received the 3rd Best Student Paper Award in the 2006 IEEE Radio and Wireless Symposium. Panayotis G. Cottis was born in Thessaloniki, Greece, in 1956. He received the Dipl. (mechanical and electrical engineering) and Dr.Eng. degrees from the National Technical University of Athens (NTUA), Greece, in 1979 and 1984, respectively, and the M.Sc. degree from the University of Manchester, (UMIST), Manchester, U.K., in 1980. In 1986, he joined the Department of Electrical and Computer Engineering, National Technical University of Athens (NTUA), Greece, where he is currently a Professor. He has published more than seventy papers in international journals and transactions. His research interests include microwave theory and applications, wave propagation in anisotropic media, electromagnetic scattering, wireless and satellite communications. Since September 2003, he is the Vice Rector of NTUA.     

Co-Channel and Adjacent Channel Interference in Wireless Cellular Communications

In this paper, the impact of co-channel and adjacent channel interference in mobile cellular radio systems on the cellular system capacity are studied. Simple empirical expressions for average signal to co-channel, signal to adjacent channel and signal to total interference ratios are obtained. The simple empirical results developed in this paper are easier to use in a cellular system design. The maximum number of bits/sec that can be transmitted over a cell area for a given bit error rate and total bandwidth, is proposed as a new definition of capacity of digital cellular systems. The capacity of a cellular system is shown to depend on the excess bandwidth and the number of active users.     

基于DTTB照射源的无源雷达直达波干扰抑制

该文根据DTTB照射源雷达各通道的特点,采用空域滤波方法来抑制直达波干扰。回波通道采用自适应波束形成与宽零陷结合的方法。参考通道采用改进的通用旁瓣对消结构以消除期望信号的影响,同时实现了宽零陷。基于DTTB信号的仿真结果表明,该文提出 的空域滤波方法是有效的。     

Performance Improvement by Microdiversity for Wideband Signals in Frequency Selective Fading Indoor Channels with Co-Channel Interference

A comprehensive analytical bit-error-rate (BER) model is presented to analyse the performance of antenna-microdiversity for wideband BPSK modulated signals in the frequency selective fading multipath channel, specified by its complex impulse response. The model includes the disturbance by intersymbol interference (ISI) and co-channel interference (CCI), as well as the channels' impact on the carrier phase- and clock recovery in the receiver. The channel impulse responses at the antenna elements are determined by taking into account the direction of arrival of the individual paths. Computational BER- and SNIR-gain results (SNIR = signal-to-noise+interference-ratio) show that a substantial performance improvement is achieved with antenna combining for wideband signals which suffer ISI and/or CCI. For the indoor multipath channel with exponentially decaying power delay profile, the performance enhancement is compared for several antenna combining schemes. Quasi-coherent equal gain combining (QCEGC) is proposed as an novel EGC scheme based on a less accurate phase estimation technique. For wideband signals, QCEGC shows a slight performance degradation when compared to maximal ratio combining or minimum mean square error combining (MMSEC), but has a much lower implementation complexity. In the channel with CCI, where the best performance is achieved with MMSEC, QCEGC performs very poor.     

单频网及其在DTTB中的应用

阐述了单频网的基本概念和技术特点，描述了单频网和各种数字电视地面广播(DTTB)标准之间的关系，并简介了当前单频网在世界主要国家的应用现状。     

Co-Channel Interference in Cellular Mobile Radio Systems with Coded PSK and Diversity

In this paper, the performance of coding and diversity in narrowband wireless cellular systems affected by fading, shadowing and co-channel interference is analyzed. We consider low-order diversity, that can be practically realized for both coherent and differential phase shift keying. We assume that the shadowing random processes affecting all transmitted signals do not vary appreciably over the transmission duration. Fading, on the contrary, is assumed to vary more rapidly. Our main focus here is on outage probability. After choosing a performance indicator, its expectation is taken with respect to fading and co-channel interference, conditionally on shadowing. Hence, the resulting average performance indicator is a random variable. The probability that this random variable exceeds a specified threshold defines the outage probability. We consider as performance indicators (i) the channel cut-off rate R₀ and (ii) the bit error rate P_b of an actual coded scheme. As we are interested in interference-limited, rather than power-limited systems, we evaluate both R₀ and P_b for very high signal-to-noise ratios. Results are parameterized by the frequency reuse factor and the diversity order.     

A General Approach for Image and Co-Channel Interference Suppression in Diversity Wireless Receivers Employing ICA

In this contribution, a general approach to suppress image signal and co-channel interference in a wireless receiver is presented. The technique employs diversity reception, and the algorithm is based on complex-valued independent component analysis (ICA). The proposed ICA method increases the channel capacity through greater frequency reuse, and it simplifies the receivers front end by eliminating the need for analog image filtering. Also, the new technique is computationally efficient and has attractive implementation features in terms of the requirement for A/D converters speed and bandpass filters selectivity. Simulation results show that the performance is robust over a wide range of input signal-to-interference ratios, and the algorithm has fast convergence.     

一种基于循环稀疏表示的同频带干扰抑制及发射源定位方法

针对无线通信中的同频信号干扰问题,受信号稀疏表示及循环平稳特性启发,本文通过建立位置坐标的样本集合,构造字典矩阵,采用优化方法在循环频域实现稀疏信号重建,利用接收到信号的循环谱切片直接估计发射源位置.仿真结果表明,该所提算法的定位误差接近于推导的克拉美劳下界,在低信噪比和信干比条件下优于现有的频域直接定位和两步定位算法,具有更高的定位精度.