Equaliser Performance for HIPERLAN in indoor channels

In order to accomplish practical deployment modelling for system performance evaluation and comparison for possible modulation and equalisation schemes to be used in HIPERLAN, a wide band tapped delay line (WTDL) channel model has been adopted by ETSI to characterise the multipath fading in the indoor radio environment. Based on this statistical channel model, and using Monte Carlo method, this paper evaluates the average probability of error for linear and decision feedback equaliser as a function of signal-to-noise ratio. It also evaluates the matched filter bound for this channel model. The results show the optimum performance levels achievable via the use of any equaliser.The work described in this paper was supported by the UK DTI/EPSRC LINK project: PC2011 High Throughput Radio Modem under EPSRC grant reference GR/K00318 in collaboration with Symbionics Networks limited.     

室内无线光通信信道分析

文章采用基于定点的迭代模型对非定向信道进行分析,得出了具体的迭代公式.在有家具的房间环境中,给出了可视光的增益公式,通过MATLAB编程实现了反射次数k=0、1、2三种情况下的脉冲响应,给出了仿真图形并加以说明.同时又对空房间的三种情况下的脉冲响应进行了仿真,通过与有家具的环境的比较,得出了随房间高度增加,非可视分量也增加的结论.     

室内分布系统多系统合路干扰影响分析

铁塔公司成立后,室内分布系统的建设由铁塔公司负责,未来多运营商共建共享将成为室内分布系统建设的主要方式,这就为多系统接入平台（POI）的应用提供更为广泛的舞台。POI的引入节省了重复投资,但由此带来的多系统干扰问题逐渐成为各运营商关注的重点。本文基于不同的POI类型,针对可能的干扰问题开展了理论分析及测试,为POI引入后的潜在干扰问题给出了解决方案,为室内分布系统的建设提供指导。     

Increasing Throughput and QoS in a HIPERLAN/2 System with Co-channel Interference

There is a growing demand for bandwidth as well as mobility. Within ETSI BRAN a wireless LAN called HIPERLAN/2 has been standardized. While data rates can be as high as 54 Mbit/s for a high carrier to interferer ratio (C/I), more robust combinations of modulation and code-rate have to be used and also retransmissions do occur when interference is present. This leads to much smaller effective data rates. Interference and link adaptation are therefore important topics. In order to have a realistic co-channel interference, two radio cells are implemented which interact with each other. In both radio cells detailed implementations of the protocols are used. Data transmission between the terminals is carried out via TCP/IP, respectively UDP. In this paper it is shown how throughput as well as delay can be improved in all load conditions by reducing co-channel interference and reducing the variations in the interference situation which significantly increases the effectiveness of link adaptation.     

Design considerations for broadband indoor infrared wireless communication systems

Recently there has been a growing interest in using infrared light for broadband indoor wireless communications. There are two major limitations for establishing a wideband infrared communications link. The first and most important limit is the power requirements of such a link. The second important impairment is the intersymbol interference caused by multipath dispersion. In this paper we address the issue of designing an optimized transmission system to provide the best power efficiency for an infrared link. Important parameters that should be considered for this design and some examples of efficient link designs are discussed. The suggested designs can improve the power efficiency of an indoor infrared link up to 4 to 8 dBo while providing a smaller rms delay spread, more robustness to shadowing and a more uniform distribution of power. Characteristics of the indoor infrared channel depends upon the directions of the receiver. This dependency can be used in designing a direction diversity receiver to decrease the rms delay spread of the received signal and to reduce the effects of noise by using proper combining techniques. We discuss the effects of receiver direction and field-of-view on the channel parameters and suggest a configuration for a direction diversity receiver.     

TD-LTE室内覆盖解决方案

室内覆盖是整体无线网络的重要组成部分,据统计70％以上的数据业务发生在室内.而由于TD-LTE的频段较高,信号传播能力较弱,室内深度覆盖受到较大限制,因此亟需通过建设室内分布系统以充分吸收室内业务,提升用户感知增强用户粘性.本文探讨了TD-LTE的室内覆盖解决方案和技术要求,对各制式间的干扰进行了初步分析,并给出解决建议,以保证室内单用户吞吐率.     

基于大数据的室内网络综合分析系统的研究和应用

针对当前电信运营商GSM/TD-SCDMA/TD-LTE/WLAN四网业务的管理中缺乏直观的呈现手段,数据分析的粒度不够精细化,数据支撑不够有效等问题提出了一种基于大数据的室内网络综合分析的解决方案,通过细化到楼宇的数据采集以及打通相关系统的数据接口,实现一套信息管理工具,可有效提高管理水平和效率。     

Location based spectrum sensing performance analysis over fading channels in cognitive radio networks

This paper analyzes the spectrum sensing performance over fading channel,in which a licensee and multiple unlicensed users coexist and operate in the licensed channel in a local area. The overall average probabilities of detection and false alarm by jointly taking the fading and the locations of all secondary users into account are derived,and a statistical model of cumulate interference is constructed. Based on the cumulate interference,a closed-form expression of outage probability at the primary user's receiver according to a specific distribution of the fading is obtained. Finally,the sensing parameters so as to minimize the total spectrum sensing error and maximize the average opportunistic throughput are obtained. It is noted that the overall average performance analysis and results here enable to benchmark the design of specific spectrum sensing algorithms.     

高层小区室分设计分析与应用

随着城市化的进展,各类大型建筑群拔地而起,对于移动通信来讲,随之带来的是给这些高层场景下的用户提供高品质的通话服务。通过哪种设计方式来满足此类需求,保证区域内信号的全方位覆盖,避免边缘地带信号杂乱、信号弱等问题。本文主要从高层小区的设计思路进行分析,以达到解决高层建筑中常见的疑难问题点。     

铁路数字电视与既有无线列调的信号干扰分析

铁路数字电视的发展是和谐社会的需要.基于无线列调对铁路运输安全的重要性,在研究铁路数字电视之初,必须考虑到铁路数字电视系统对既有的无线列调系统不能造成干扰.在对两个系统进行对比分析研究的基础上,排除了铁路数字电视信号对无线列调的信号存在干扰的可能,为铁路数字电视的发展提供了切实有效的基础.     

端到端无线信道信号幅度和多普勒谱分布研究

利用理论和实验相结合的方法研究了室内宽带端到端(Device-to-Device,D2D)无线信道信号的幅度和多普勒频谱分布.结果表明:在不同的场景下,D2D信号幅度分布服从单瑞利、双瑞利和多瑞利的复合分布;在二维(Two-Dimension,2-D)和三维(Three-Dimension,3-D)散射环境下随电波到达角的分布不同,D2D信道多普勒频谱将遵循不同的分布规律.通过理论和实验结果的比较研究验证了本文结果的正确性.     

短程脉冲无线信道特性仿真与分析

利用仿真语言对短程脉冲无线信道进行仿真研究。考虑短程脉冲无线传播环境为具有某一密度的随机分布的散射体,在一种理想情况下,信道传播环境表现为一个渗透网格。利用仿真语言仿真短程脉冲无线信道中多径分量的传播轨迹,通过脉冲无线信道的随机模型对短程脉冲无线信道特性进行仿真分析,仿真结果表明：利用该模型对短程脉冲无线信道仿真是有效的。     

蓝牙抗干扰技术及2.4GHz无线网络频率共存分析

介绍了工作于2．4GHz的几种无线网络技术的特点，对其性能作了比较，并从噪声系数指标及抗同频干扰等方面分析了蓝牙的抗干扰性能，同时讨论了2．4GHz频段无线电设备的共存机制。     

Performance analysis of cognitive relay systems with spectrum-sharing interference under a primary outage probability constraint简

This paper investigates the performance of an underlay cognitive relay system where secondary users（SUs） suffer from a primary outage probability constraint and spectrum-sharing interference imposed by a primary user（PU）. In particular, we consider a secondary multi-relay network operating in the selection decode-and-forward（SDF） mode and propose a best-relay selection criterion which takes into account the spectrum-sharing constraint and interference. Based on these assumptions, the closed-form expression of the outage probability of secondary transmissions is derived. We find that a floor of the outage probability occurs in high signal-to-noise ratio（SNR） regions due to the joint effect of the constraint and the interference from the PU. In addition, we propose a generalized definition of the diversity gain for such systems and show that a full diversity order is achieved. Simulation results verify our theoretical solutions.     

第八讲 HDTV的频谱利用和服务区计算

本文简要地介绍了有关ＨＤＴＶ频谱利用方面的一些基本概念,如同播、服务区、接纳比等;介绍了美国对ＮＴＳＣ和ＡＴＶ服务区计算的一些考虑;最后讨论了关于克服“峭壁效应”的某些方法。     

Performance analysis of beamforming in two-hop AF relay networks with antenna correlation and interference

This paper investigates the performance of a two-hop amplify-and-forward (AF) relay network with antenna correlation and co-channel interference (CCI) over Rayleigh fading channels. In this network, the relay has multiple antennas while both the source and destination are equipped with a single antenna. By assuming that the statistical channel state information (SCSI) is available at the relay, the maximal output signal-to-interference-plus-noise ratio (SINR) is first obtained. Then, with the help of the specialized functions, the analytical expressions for the outage probability (OP), Ergodic capacity and average symbol error rates (ASERs) of the considered AF relay network are all derived. Moreover, the asymptotic analysis at high signal-to-noise ratio (SNR) is also presented to reveal the diversity order and array gain of the relay system. Finally, computer simulations are given to confirm the validity of the theoretical analysis and indicate the effects of antenna correlation and interference on the system performance.     

室内线路的故障分析及检修方法

在室内照明线路的安装和维修过程中,电工应掌握基本技术、正规合理且整齐牢固的安全检修.除了要熟知室内照明线路的具体类型、结构和原理外,还要清楚安装和维修典型室内照明线路的有关工艺技术,以达到技术要求标准,最终确保安全用电.本文从室内照明线路的相关工艺入手,对室内照明线路的故障和检修进行了深入分析.希望通过对其工艺、故障原因分析及检修方法的介绍能帮助学生快速找到故障点并排除,为日后的实际工作提供专业技术和安全保障.     

Performance of a Multiple-Antenna Multiple-Equalizer System for a CDMA Indoor Wireless System

A multiple-antenna multiple-equalizer (MAME) system for interferencesuppression in some code-division multiple-access (CDMA) indoor wirelesssystems is investigated. The MAME system offers enhanced interferencesuppression capabilities over existing approaches under certain conditions andcan thus increase system capacity. The details of the MAME system arediscussed and the unique features of this work as compared with many otherstudies on space-time processing are explained using spectral correlation anddiversity domain concepts. The effects of the number of antennas, tap spacingof the equalizers, spectral correlation, and diversity domains are discussedusing simulation results. Adaptation performance results are also presentedand a recently proposed quasi-Newton algorithm is recommended for use in theMAME system. Decision-directed equalization results are also studied undervarious conditions and bit-error rate results are presented. Simulationresults illustrate that the MAME system can offer enhanced interferencesuppression capabilities in CDMA indoor wireless systems.     

Design and Evaluation of a QoS-aware Framework for HIPERLAN/2 Networks

Recent advances on wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper, we present a QoS framework to support various types of services in a wireless networking environment. Under this QoS framework, we propose various resource request mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting different services, such as video, voice, best-effort and background traffic. Francisco M. Delicado This author received his M.Sc. degree in Physics (Electronics and Computer Science) from the University Complutense of Madrid, Madrid, Spain in 1995. He is currently a Ph.D. degree student in the Department of Computer Engineering at the University of Castilla-La Mancha. His research interests include high-performance networks, specially wireless LAN, QoS over WLAN, video compression, video transmission and error-resilient protocol architectures. Pedro Cuenca This author received his M.Sc. degree in Physics (Electronics and Computer Science, award extraordinary) from the University of Valencia in 1994. He got his Ph.D. degree in Computer Engineering in 1999 from the Polytechnic University of Valencia, Spain. In 1995 he joined the Department de Computer Engineering at the University of Castilla-La Mancha. He is currently an Associate Professor of Communications and Computer Networks. He has also been a visiting researcher at The Nottingham Trent University, Nottingham (England) and at the Multimedia Communications Research Laboratory, University of Ottawa (Canada). His research topics are centered in the area of high-performance networks, wireless LAN, video compression, QoS video transmission and error-resilient protocol architectures. He has served in the organization of International Conferences as Session Chair. He has been reviewer for several Journals and for several International Conferences. He is a member of the IFIP 6.8 Working Group and a member of the IEEE. Luis Orozco-Barbosa This author received the B.Sc. degree in electrical and computer engineering from Universidad Autonoma Metropolitana, Mexico, in 1979, the Diplome d'Etudes Approfondies from ENSIMAG, France, in 1984 and the Doctorat de l'Universite from Universite Pierre et Marie Curie, France, in 1987, both in computer science. From 1991 to 2002, he was a Faculty Member of Computer Engineering at the School of Information Technology and Engineering (SITE), University of Ottawa, Canada. In 2002, he joined the Department of Computer Engineering at Universidad de Castilla La Mancha (SPAIN) where he is currently Director of the Albacete Research Institute of Informatics. He has published over 180 papers in international Journals and Conferences on computer networks and performance evaluation. His current research interests include Internet protocols, video communications, wireless networks, traffic modeling and performance evaluation. He is a member of the IEEE. Antonio Garrido This author received the degree in physics (electronics and computer science) and the Ph.D. degrees from the University of Granada, Spain, in 1986 and University of Valencia, Spain, in 1991, respectively. In 1986, he joined the Department of Computer Engineering at the University of Castilla-La Mancha, where he is currently a Full Professor of Computer Architecture and Technology and Dean of the EscuelaPolitecnica Superior de Albacete (School of Computer Engineering). His research interests include high-performance networks, telemedicine, video compression, and video transmission. He has published over 40 papers in international journals conferences on performance evaluation of parallel computer and communications systems and compression and transmission in high-speed networks. He has led several research projects in telemedicine, computer networks and advanced computer system architectures.