Co-channel and self-interference analysis for indoor wireless channels

To achieve a user data rate of 20 Mbit/s in the high performance local area network (HIPERLAN) system operating in indoor environments, channel equalization must be used to mitigate the effects of multipath propagation. If, however, the indoor channel impulse response length is too long, then the multipath power outside of the equalisation capability of the equalizer acts as a form of self interference. Moreover, co-channel interference may also be present at the detector input. Considering these two effects as well as the rms delay spread, this paper derives analytical expressions for the probability of outage.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/K 00318 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.     

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。     

Performance of a Modified ATDMA Based System in an Indoor Mixed Traffic Environment

This paper examines the performance of a modified Advanced Time Division Multiple Access (ATDMA) protocol when supporting mixed voice and bursty data users in an indoor propagation environment. The performance analysis was performed by a Monte Carlo simulator, the accuracy of which was verified by a simplified Markov model analysis. The system model includes Rice fading, log-normal shadowing, distance dependent pathloss and co-channel interference. The system model also considers preferential channel access based on the capture effect. The results suggest the necessity of modifying the ATDMA frame from the traditional structure and indicate that the ATDMA frame structure could be adaptively modified based on the traffic loading in the system.     

A patch antenna for HIPERLAN

A patch antenna suited for indoor HIPERLAN is presented. The antenna operates in T M ₀₂ mode and its radiation pattern is omnidirectional in azimuth and has a null in the normal direction. An experimental prototype has been designed and tested. A 6.1% bandwidth of VSWR2 and 4.2 dB antenna gain were measured at 5 GHz band.     

Building information systems based on precise indoor positioning

During the last 10 years, many modern IT-based applications have developed inside buildings. Many of those applications would benefit by the ability to locate people and/or objects inside the building (indoor positioning). However, most of today's indoor positioning systems are not able to deliver precise position information (<10?cm) along with quality parameters. Ultra wide band (UWB) is a new radio-based technology that allows the determination of distances in indoor environments with a very high spatial resolution even through building materials. At the Institute of Geodesy of TU Darmstadt, a high-resolution UWB positioning system (UWB-ILPS; ILPS, indoor local positioning systems) based on trilateration principle has been developed to estimate the position of a mobile station precisely. To benefit from knowing the position and orientation, it is necessary to select and merge data linked to the user's location for indoor location services. By this means, the visitor to a public building may benefit from the system as his position is shown on a digital floor plan generated dynamically or by retrieving location-based information inside the building. Mixed reality systems also offer advantages for a mobile building information system. For this purpose, a webcam was replaced by the digital camera in the UWB-ILPS prototype. Knowing the camera's location in space and its view direction, one is able to merge the real world taken by the webcam with the virtual world represented by a 3D CAD model of the building.     

ZigBee室内定位系统定位精度优化算法研究

基于ZigBee进行室内无线定位系统的开发已经成为热点,这是由于采用无线通信可以节省成本,使用也更加方便.但同时,基于接收信号强度指示(RSSI)的测距和定位易受多种因素的影响,使得测距和定位的误差都比较大.提出了针对室内小环境范围内的定位系统,提出了获取RSSI的方法(中值过滤和均值过滤)和定位的优化算法(基于极大似然估计法加权取均值的定位优化算法),通过两种方法的结合,提高了定位精度.同时,利用LabVIEW软件开发上位机.     

卡尔曼滤波在iBeacon室内定位系统中的应用

为了抑制iBeacon信号在传播过程中由于人员扰动、多径效应等引起的噪声,以及移动定位过程中定位结果的不稳定,在iBeacon室内定位系统中引入了卡尔曼滤波算法分别对采集到的iBeacon信号与移动定位结果进行处理.首先通过卡尔曼滤波对采集的信号进行处理,降低了信号噪声,提高了信号的质量,其次应用卡尔曼滤波对移动定位结果进行二次处理,提高了移动定位结果的稳定性与精度.实验结果表明,在办公室环境下采用卡尔曼滤波进行处理后可将1 m以内的定位精度提高到80%以上.     

Automatic virtual calibration of range‐based indoor localization systems

The localization methods based on received signal strength indicator (RSSI) link the RSSI values to the position of the mobile to be located. In the RSSI localization techniques based on propagation models, the accuracy depends on the tuning of the propagation models parameters. In indoor wireless networks, the propagation conditions are hardly predictable due to the dynamic nature of the RSSI, and consequently the parameters of the propagation model may change. In this paper, we present an automatic virtual calibration method of the propagation model that does not require human intervention; therefore, can be periodically performed, following the wireless channel conditions. We also propose a novel RSSI‐based localization algorithm that selects the RSSI values according to their strength, and uses a calibrated propagation model to transform these values into distances, in order to estimate the position of the mobile. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of an ultra‐wide bandwidth wireless indoor non‐line‐of‐sight channels

In this paper, based on the analysis of the experimental data using a new post‐processing method for time‐domain channel measurements, a new double‐cluster statistical model for UWB systems with a bandwidth lower than 1 GHz in non‐line‐of‐sight (NLOS) indoor propagation environment is proposed. By using the proposed model, both the model itself and the parameter estimation of the corresponding model are simplified. By defining the polarity of a particular model parameter, the model has the flexibility to deal with both ‘soft NLOS’ and ‘hard NLOS’ indoor propagation environments. Therefore, the channel impulse responses (CIRs) generated by the proposed model ‘resemble’ the measured CIR better than the SV (Saleh‐‐Valenzuela)/IEEE 802.15.3a model not only in terms of the average values, but also in terms of the cumulative distribution functions (CDFs) of the small‐scale statistics. Copyright © 2008 John Wiley & Sons, Ltd.     

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...     

超宽带室内多径信道特性的最优化分析

分析超宽带(UWB)信道特性并建立合适的信道模型是UWB无线通信研究的重要内容。采用最优化方法分析UWB室内多径信道的特性,并讨论构建UWB信道的数学模型。在此基础上通过引入随机桥过程假设和概率选择性假设,使用最优化方法建立UWB信道冲激响应的有约束布朗桥模型(BBBM);分析BBBM模型有效随机路径判据,给出在最优化框架基础上的建模算法;使用BBBM模型对UWB信道进行仿真分析,得到的UWB信道特性和用实验测量与UTD方法得到的信道特性非常相似,特征参量的取值与实际情况相符。     

ILONA: indoor localization and navigation system

Indoor positioning is a hot topic these days and there is a growing need for it in public buildings such as airports, hospitals, universities or shopping malls. Indoor positioning systems should be accurate, easily available for the users, with low installation and maintenance cost, which makes development challenging. Existing systems are based on various technologies such as ultrasonic, RFID, WiFi or light encoding. Moreover, these systems are tailored to a given environment and usually rely on a single technology. This paper presents the indoor localization and navigation (ILONA) System, a flexible hybrid indoor positioning and navigation framework. The ILONA System was not designed to be a solution for a single indoor positioning task but to be a standard core component of various systems. The ILONA System provides easily available positioning and navigation services for the end users. The system can manage data from the most commonly available sensors of modern smart phones. Thus, the ILONA System can perform positioning based on various technologies. ILONA System can be established at low cost because it only requires a connection between the server and the clients and WLAN is usually available. Hence, the presented ILONA System provides a widely available, hybrid indoor positioning framework at low cost to the developers of other indoor positioning solutions.     

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.     

在室内通信环境下UWB信号设计及性能分析

采用的脉冲波形在满足联邦通信委员会(FCC)发射要求的基础上,提出了在室内通信环境下,经过脉冲位置调制(PPM)的UWB信号延迟参数的优化设计方法,相对于传统的方法,性能有明显的提升。同时结合信号的数学模型,对信号的误码性能进行了分析与比较,这对于UWB系统在实际系统中的使用有很好的指导意义。     

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.     

Adaptive non-linear equalisation of digital communications channels

Non-linear distortion introduced by communications channels increases the probability of error. In this paper, an adaptive non-linear canceller is presented which attempts to remove non-linear interference from the output of a feedforward or decision feedback equaliser, improving the error rate. It may be implemented using a memory look-up table architecture, making it suitable for high speed real time operation.     

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。     

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。