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.     

用于3G室内覆盖的微型干扰消除直放站的研究

3G网络的数据业务主要发生在室内,深度覆盖是当前运营商亟待解决的问题.文章介绍了一种采用数字回声消除技术的微型干扰消除直放站,它采用一体化设计,将施主天线和重发天线集成到其中,用户无需进行额外的布线和装配天线,方便安装.实际应用表明:该直放站是一种解决因建筑物导致的信号衰减和信号盲区等室内深度覆盖问题的经济、快速的解决...     

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。     

基于信道转换的蓝牙微微网之间同频干扰抑制方法

多个蓝牙微微网之间的同频干扰十分严重,该文针对此问题提出一种基于信道转换的同频干扰抑制方法。该方法在蓝牙微微网重传时进行信道转换,以同频不一定会产生干扰为前提,综合考虑了返回分组、跳频保护间隔、3种时隙分组共存等多种情况,使分析更加接近真实情况。对网络性能指标进行大量仿真,由仿真分析可见,该方法有效地降低了蓝牙微微网的分组错误率,提高了微微网的吞吐量,尤其当网络数量在14~57范围内时,微微网吞吐量最大可增加260 kbps。     

TRM-FMM室内无线定位技术

在室内多径环境下信号视距传播易受障碍物影响,导致现有的一些室内定位技术对室内环境分布的估计较为困难。时间反转镜( TRM)室内无线定位技术可以有效地减少室内多径效应对信号的影响以及复杂环境造成的延时。但是,若没有信号传输信道的信息,常规TRM技术的定位精度就会大打折扣。针对该问题,给出了一种基于快速行进算法( FMM)的TRM室内无线定位方法。该方法首先利用FMM和同时代数重建算法( SART )迭代更新计算室内环境分布,然后使用估计结果进行TRM定位。仿真结果显示,对于小型规模的目标物体定位误差约为1.84 cm,在未知室内信道信息的仿真环境下,该方法比常规TRM技术的定位精度提高约32.90倍。     

基于压缩感知的室内多目标无线定位算法

针对现存无线传感器网络定位算法中需要采集、存储和处理大量数据导致运算量较大与能耗过高的问题,提出了一种改进的基于贝叶斯压缩感知的多目标定位算法.该算法利用锚节点对监控区域的划分,结合贝叶斯压缩感知理论将多目标定位问题转换为稀疏信号重构的问题.针对传统观测矩阵难以实现的缺陷,该算法中改进观测矩阵的设计可实现且与稀疏变换基相关性较低,进而使得算法的重构性能较高,从而降低了定位的误差.仿真结果表明,与现有的一些方法相比,所提算法在保证较低的计算复杂度的情况下更加充分地利用了网络节点,有效提高了定位精度,同时具有较强的鲁棒性.     

基于变换域和时域联合处理的雷达同频干扰抑制方法

针对舰艇编队情况下线性调频脉冲体制雷达间同频干扰的问题,该文提出一种分数阶傅里叶域滤波处理与时域反异步处理相结合的干扰抑制方法。通过分数阶傅里叶域自适应滤波对与目标回波信号调频率不同的干扰信号做抑制处理,同时根据分数阶傅里叶变换的可逆性,逆变换到时域后采用相邻周期反异步方法进一步消除与目标回波信号调频率相同或相近的同频干扰。仿真试验表明,该方法相对传统方法能够有效抑制与目标回波信号调频率不同的同频干扰,同时对于在时域与目标回波信号完全重合或部分重合的干扰信号也有较好的抑制效果,干扰抑制处理增益达到29 dB以上。该方法为提高同型雷达编队组网能力提供了设计参考。     

Performance analysis of broadband self-interference cancellation at RF domain in co-frequency co-time full duplex systems

Due to the lack of performance analysis of the RF domain broadband self-interference cancellation algorithms in the co-time and co-frequency full duplex system,the multi-tap RF domain self-interference cancellation structure were considered,and the optimal solutions of its parameters to minimize the residual interference signal power were discussed,then its achievable interference cancellation capability was analyzed.By analysis and simulation,the performance of the multi-tap structure was associated with the interference bandwidth,the carrier frequency,and the differences between the multi-tap delays and multipath delays of the self-interference channel.The greater the signal bandwidth is,or the larger the differences between the multi-tap delays and multipath delays are,the worse the interference cancellation performance is.Besides,the interference cancellation performance is periodic oscillation with the increase of carrier frequency.     

Performance of dual-hop wireless communication systems over the α–μ fading channels

In this paper, we consider a dual-hop wireless communication system with non-regenerative relay node and we study its performance over the α–μ fading channels. Specifically, we derive a closed-form expression for the moment generating function (MGF) of the harmonic mean of end-to-end signal-to-noise ratio (SNR) assuming the α–μ fading models. We also derive closed-form expressions for the end-to-end outage probability and average bit error rate of coherent modulation techniques. The obtained expressions can be reduced to study the performance of dual-hop communication systems over other fading channel models by using the proper values for the α and μ parameters. Numerical results are provided and conclusion remarks are drawn.     

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.     

无线激光DH-PIM室内通信系统性能分析

研究了加性高斯白噪声和多径码间串扰下采用双头脉冲间隔调制(DH-PIM)的无线激光室内通信系统的性能,对DH-PIM系统的符号结构、带宽、差错率特性等方面进行了分析,并与OOK,PPM和DPIM调制方式做了比较。     

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。     

Design alternatives for wireless local area networks

In this paper an overview of the wireless local area network (LAN) area is provided. The two types of wireless LAN topologies used today, infrastructure and ad hoc, are presented. The requirements that a wireless LAN is expected to meet are discussed. These requirements impact on the implementation of both the Physical and MAC layer of a wireless LAN. The unique characteristics of wireless physical layers are discussed and the five technology alternatives used today are presented. MAC layer issues are discussed and the two existing standards, IEEE 802.11 and HIPERLAN 1, are examined. Polling‐based MAC protocols (RAP, GRAP) are also reviewed. Finally, an introduction is made to wireless technologies that interact with WLANs, such as personal area networking (PAN) and wireless ATM and an overview of HIPERLAN 2, a WLAN using ATM technology, is provided. Copyright © 2001 John Wiley & Sons, Ltd.     

D2D通信中一种基于非数据辅助误差适量幅度的同信道干扰控制方法及其性能分析

针对D2D通信系统中广泛存在的同信道干扰问题,该文提出一种基于非数据辅助误差矢量幅度(NDA-EVM)进行同信道干扰分析的方法.以NDA-EVM作为信道质量评估参量,推导信号在M-QAM调制下的NDA-EVM统一计算模型,利用信道增益建立NDA-EVM同信道干扰分布模型,并进一步求解该模型的性能上限,从而量化同信道干扰...     

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。     

Relay selection for secrecy connectivity in random wireless networks

In the paper, we study the problem of secure connectivity for colluding eavesdroppers using relay selection in random wireless networks, where the relay nodes and eavesdroppers are all randomly distributed according to two independent Poisson point process. The decode‐and‐forward and randomize‐and‐forward two relay strategies are considered, and a new metric is defined for best relay selection and random relay selection. We derive closed‐form expressions for the secrecy outage probability for the two relay strategies. In particular, the effect of power allocation ratio and the maximum ratio combing at the destination node on the secrecy outage probability is demonstrated for the decode‐and‐forward relay strategy. Numerical results illustrate the secrecy performance gains with collaborative transmit diversity. © 2016 The Authors. Wireless Communications and Mobile Computing Published by John Wiley & Sons Ltd.     

室内无线定位算法研究现状与发展趋势

随着无线定位技术的飞速发展，人们对室内定位需求的上升，室内环境的定位技术成为近年来的研究热点。考虑到室内定位的关键技术包含了许多方面，首先概述了目前室内定位主要的所面临的问题，分析了室内定位误差的主要来源；针对如何减少定位误差，将室内定位理论主要分为信道建模以及定位算法两个部分进行分析介绍；最后总结了现有的研究，指出了未来该领域的研究热点和发展趋势。     

无线 Mesh 网络部分重叠信道分配综述

无线Mesh网络面临的主要挑战是由共信道干扰导致的网络容量下降问题,仔细规划部分重叠信道的使用能减少甚至消除共信道干扰。在介绍部分重叠信道基本概念的基础上,重点从单播和多播2个角度对国内外部分重叠信道分配研究领域的成果进行了分类总结与分析;深入剖析部分重叠信道分配中的难点与挑战,并展望了未来的研究方向,以期促进无线Mesh网络向“最后一公里”接入的理想解决方案演进。