실내 환경에서 초광대역 채널에 미치는 인체의 영향

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 김성철.In this dissertation, the effects of human body on Ultra Wideband (UWB) channel in indoor environments are represented. Unlike previous communication system, UWB system has a large bandwidth. This leads to interference to the other communication systems in the same frequency bands. This feature makes UWB system deployable in line-of-sight (LOS) and slightly cluttered non-line-of-sight (NLOS) environment in which the signal undergoes less attenuation. In these environments, the UWB channel largely depends on surroundings of a transmitter (Tx) and receiver (Rx) antennas. In indoor environments, a human body is a major factor that changes channel characteristics. This dissertation dealt with the effect of human body on the UWB channel in indoor environments. First, this dissertation addresses UWB channel variation depending on the number of people in indoor LOS environments. To assess variation of UWB channels, four environments which have different room sizes and wall structures are considered. During measurements, people did not move around, but were just sitting on their chair with small motion if necessary. Because the UWB system operates in a wide bandwidth compared to previous communication systems, it is necessary to understand the frequency correlation characteristics of UWB channels. We found the correlation coefficients between two frequency tones with an interval of 10MHz are smaller than about 0.5. In the dissertation, we deal with a distance-dependent path-loss model, a frequency-dependent path-loss model, and time dispersion parameters. To provide a general channel model, we obtained the linear regression model with population density for each parameter. Next, the dissertation considered a situation where either LOS path is not blocked or slightly blocked by human bodies as a Rx is shifted by small-scale (1λ) distance while a Tx is fixed. In this situation, we measure the small-scale amplitude statistics in the absence and presence of human bodies and propose a statistical model of the small-scale fading distribution. From the measurement data, we found the best fitted channel model among several typical theoretical distribution models such as Lognormal, Nakagami, and Weibull distributions, showing good agreement with the empirical channel data. In the last part of dissertation, we dealt with the performance analysis of impulse radio (IR) UWB system based on the proposed small-scale fading distribution and also compare the performance with the existing channel model. Due to the fine time resolution of UWB system, the system mainly uses a rake receiver which consists of a number of correlators that are sampled at the delays related to specific number of multipath components. The dissertation considers two types of rake receiver, selective combining (SC) and partial combing (PC) rake receiver. The standard channel model, IEEE 802.15.4a, shows the best bit-error-rate (BER) performance. But this model does not include the effect of human body. When the effect of human body is included on 802.15.4a model, the BER performance is deteriorated.Chapter 1 Introduction.............................................................1 1.1 UWB system................................................................................1 1.2 UWB channel standard model.....................................................2 1.2.1 IEEE 802.15.3a……....................................................................2 1.2.2 IEEE 802.15.4a……....................................................................2 1.3 Motivation……....................................................................................3 1.4 Dissertation Outline............................................................................5 Chapter 2 Modeling of UWB channel with Population density in indoor LOS Environments................... ...............................6 2.1 Introduction..................................................................................6 2.2 Measurement Methodology ........................................................8 2.2.1 Measurement System...................................................................8 2.2.2 Measurement Scenario.................................................................9 2.3 Frequency Correlation Coefficient of the Measured Channel Gains ................................................................................................12 2.4 Path-Loss Characteristics……………………………………..15 2.4.1 Empirical distance-dependent path-loss model.........................15 2.4.2 Empirical frequency-dependent path-loss model......................18 2.5 Time-Dispersion Parameters.....................................................22 2.6 Conclusion...………..................................................................26 Chapter 3 Human body Affected Small-Scale Fading for indoor UWB channel…….....................................................27 3.1 Introduction................................................................................27 3.2 Measurement Campaign………………………………………28 3.2.1 Measurement System………………………………................28 3.2.2 Measurement Scenario…...........................................................28 3.3 Statistical Modeling of Small-Scale Fading ………….…………35 3.4 Small-Scale Fading Distribution by Body………….…………37 3.5 Conclusions................................................................................48 Chapter 4 Performance Analysis of Rake receiver in IR-UWB system………………………………………………………49 4.1 Introduction................................................................................49 4.2 UWB Rake receiver…....….......................................................51 4.2.1 UWB Rake receiver structure... ………………........................51 4.2.2 Rake Receiver Type... ………………………..........................54 4.3 Channel models…………………………….............................56 4.3.1 801.15.4a UWB channel model ……………….......................56 4.3.2 People Shadowing Effect on UWB Channels...........................58 4.4 BER performance analysis.........................................................60 4.5 Conclusion..................................................................................66 Bibliography..........................................................................67 Abstract in Korean.................................................................70Docto

Radio channel characterisation and system-level modelling for ultra wideband body-centric wireless communications

PhDThe next generation of wireless communication is evolving towards user-centric networks, where constant and reliable connectivity and services are essential. Bodycentric wireless network (BCWN) is the most exciting and emerging 4G technology for short (1-5 m) and very short (below 1 m) range communication systems. It has got numerous applications including healthcare, entertainment, surveillance, emergency, sports and military. The major difference between the BCWN and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile medium from the radio propagation perspective and it is therefore important to understand and characterise the effect of the human body on the antenna elements, the radio propagation channel parameters and hence the system performance. In addition, fading is another concern that affects the reliability and quality of the wireless link, which needs to be taken into account for a low cost and reliable wireless communication system for body-centric networks. The complex nature of the BCWN requires operating wireless devices to provide low power requirements, less complexity, low cost and compactness in size. Apart from these characteristics, scalable data rates and robust performance in most fading conditions and jamming environment, even at low signal to noise ratio (SNR) is needed. Ultra-wideband (UWB) technology is one of the most promising candidate for BCWN as it tends to fulfill most of these requirements. The thesis focuses on the characterisation of ultra wideband body-centric radio propagation channel using single and multiple antenna techniques. Apart from channel characterisation, system level modelling of potential UWB radio transceivers for body-centric wireless network is also proposed. Channel models with respect to large scale and delay analysis are derived from measured parameters. Results and analyses highlight the consequences of static and dynamic environments in addition to the antenna positions on the performance of body-centric wireless communication channels. Extensive measurement i campaigns are performed to analyse the significance of antenna diversity to combat the channel fading in body-centric wireless networks. Various diversity combining techniques are considered in this process. Measurement data are also used to predict the performance of potential UWB systems in the body-centric wireless networks. The study supports the significance of single and multiple antenna channel characterisation and modelling in producing suitable wireless systems for ultra low power body-centric wireless networks.University of Engineering and Technology Lahore Pakista

Modelling and characterisation of antennas and propagation for body-centric wireless communication

PhDBody-Centric Wireless Communication (BCWC) is a central point in the development of fourth generation mobile communications. The continuous miniaturisation of sensors, in addition to the advancement in wearable electronics, embedded software, digital signal processing and biomedical technologies, have led to a new concept of usercentric networks, where devices can be carried in the user’s pockets, attached to the user’s body or even implanted. Body-centric wireless networks take their place within the personal area networks, body area networks and body sensor networks which are all emerging technologies that have a broad range of applications such as healthcare and personal entertainment. The major difference between BCWC and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile environment from radio propagation perspective and it is therefore important to understand and characterise the effect of the human body on the antenna elements, the radio channel parameters and hence the system performance. This is presented and highlighted in the thesis through a combination of experimental and electromagnetic numerical investigations, with a particular emphasis to the numerical analysis based on the finite-difference time-domain technique. The presented research work encapsulates the characteristics of the narrowband (2.4 GHz) and ultra wide-band (3-10 GHz) on-body radio channels with respect to different digital phantoms, body postures, and antenna types hence highlighting the effect of subject-specific modelling, static and dynamic environments and antenna performance on the overall body-centric network. The investigations covered extend further to include in-body communications where the radio channel for telemetry with medical implants is also analysed by considering the effect of different digital phantoms on the radio channel characteristics. The study supports the significance of developing powerful and reliable numerical modelling to be used in conjunction with measurement campaigns for a comprehensive understanding of the radio channel in body-centric wireless communication. It also emphasises the importance of considering subject-specific electromagnetic modelling to provide a reliable prediction of the network performance

Measurement-Based Modeling of Wireless Propagation Channels - MIMO and UWB

Future wireless systems envision higher speeds and more reliable services but at the same time face challenges in terms of bandwidth being a limited resource. Two promising techniques that can provide an increased throughput without requiring additional bandwidth allocation are multiple-input multiple-output (MIMO) systems and ultra-wideband (UWB) systems. However, the performance of such systems is highly dependent on the properties of the wireless propagation channel, and an understanding of the channel is therefore crucial in the design of future wireless systems. Examples of such systems covered by this thesis are wireless personal area networks (papers I and II), vehicle-to-vehicle communications (paper III), board-to-board communications inside computers (paper IV) and sensor networks for industrial applications (paper V). Typically, channel models are used to evaluate the performance of different transmission and reception schemes. Channel modeling is the focus of this thesis, which contains a collection of papers that analyze and model the behavior of MIMO and UWB propagation channels. Paper I investigates the fading characteristics of wireless personal area networks (PANs), networks that typically involve human influence close to the antenna terminals. Based on extensive channel measurements using irregular antenna arrays, typical properties of PAN propagation channels are discussed and a model for the complete fading of a single link is presented. Paper II extends the model from paper I to a complete MIMO channel model. The paper combines the classical LOS model for MIMO with results from paper I by prescribing different fading statistics and mean power at the different antenna elements. The model is verified against measurement data and the paper also provides a parameterization for an example of a PAN scenario. Paper III presents a geometry-based stochastic MIMO model for vehicle-to-vehicle communications. The most important propagation effects are discussed based on the results from extensive channel measurements, and the modeling approach is motivated by the non-stationary behavior of such channels. The model distinguishes between diffuse contributions and those stemming from interaction with significant objects in the propagation channel, and the observed fading characteristics of the latter are stochastically accounted for in the model. Paper IV gives a characterization of UWB propagation channels inside desktop computer chassis. By studying measurement results from two different computers, it is concluded that the propagation channel only shows minor differences for different computers and positions within the chassis. It is also found out that the interference power produced by the computer is limited to certain subbands, suggesting that multiband UWB systems are more suitable for this type of applications. Paper V describes a UWB channel model based on the first UWB measurements in an industrial environment. Analyzing results from two different factory halls, it is concluded that energy arrives at the receiver in clusters, which motivates the use of a classical multi-cluster model to describe the channel impulse response. Parts of the results from this paper were also used as input to the channel model in the IEEE 802.15.4a UWB standardization work. In summary, the work within this thesis leads to an increased understanding of the behavior of wireless propagation channels for MIMO and UWB systems. By providing three detailed simulation models, two for MIMO and one for UWB, it can thus contribute to a more efficient design of the wireless communications systems of tomorrow

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Ultra-Wideband Channel Measurement and Modeling for Unmanned Aerial Vehicle to Wearable Device

Ultra-Wideband (UWB) has impacted our lives in impressive ways, it is one of the high potential areas with enormous benefits, especially for the short-range communication. With more discoveries, technology changed and the importance of wideband network was favored over narrowband. Officially, in the year 1933, Armstrong found and recognized the advantages of wideband signaling. Later, UWB was coined and took a fast pace and changed the conduct of the society in many ways. The most significant part about UWB is its applications, one of the claims i.e., Off-body is thoroughly studied and analyzed throughout the thesis.We performed one of the first vertical link channel studies with Off-body channel characterization with one UWB antenna patch on Unmanned Aerial Vehicle (UAV) and another antenna at different body locations on a real human subject for the frequency bandwidth of 3.1-10.6 GHz in different environments such as anechoic, indoor, and outdoor. The main purpose is to monitor how UWB system is affected by both large and small-scale fading, that's why it was worth taking measurements in all three settings for the analysis. Also, it was critical to pick one best distributions among Lognormal, Rayleigh, Nakagami, Normal, Weibull, Gamma, Exponential and Rician using Akaike Information Criteria (AIC). The path loss varies in different environments, and its exponent becomes important parameter to be determined for all three settings.It was interesting to study how UWB characteristics varied with different environments. The delay profiles such as power delay profile (PDP), root mean square (RMS), maximum excess and mean excess delays were analyzed. For all the analysis, we used two small, light weighted compatible antenna patches, which supported UWB bandwidth and consumed less power so that it could be safely attached to a human body.Our work is mainly focused on the detailed understanding of standard UWB path loss and delay spreads for the communication channel between UAV and wearable. We believe this study would help us in understanding UWB Off body characteristics thoroughly and would also help in health monitoring and improvising the optimum location of the human body tag.Electrical Engineerin

COMPARING THE ACCURACY OF BLUETOOTH LOW ENERGY AND UWB TECHNOLOGY FOR IN-ROOM POSITIONING

The purpose of this project is to thoroughly compare the accuracy of UWB and BLE distance estimations. A ranging methodology is used to gather data with both technologies, and complex algorithms are used to realize distance estimations with MATLAB. Cramer Rao Lower Bound theory demonstrates that estimations made using UWB are both more accurate and more precise than those made with BLE, where UWB can correctly locate with centimeter accuracy, while BLE is limited to meter accuracy

Antenna and radio channel characterisation for low‐power personal and body area networks

PhDThe continuous miniaturisation of sensors, as well as the progression in wearable electronics, embedded software, digital signal processing and biomedical technologies, have led to new usercentric networks, where devices can be carried in the user’s pockets, attached to the user’s body. Body-centric wireless communications (BCWCs) is a central point in the development of fourth generation mobile communications. Body-centric wireless networks take their place within the personal area networks, body area networks and sensor networks which are all emerging technologies that have a wide range of applications (such as, healthcare, entertainment, surveillance, emergency, sports and military). The major difference between BCWC and conventional wireless systems is the radio channels over which the communication takes place. The human body is a hostile environment from a radio propagation perspective and it is therefore important to understand and characterise the effects of the human body on the antenna elements, the radio channel parameters and, hence, system performance. This thesis focuses on the study of body-worn antennas and on-body radio propagation channels. The performance parameters of five different narrowband (2.45 GHz) and four UWB (3.1- 10.6 GHz) body-worn antennas in the presence of human body are investigated and compared. This was performed through a combination of numerical simulations and measurement campaigns. Parametric studies and statistical analysis, addressing the human body effects on the performance parameters of different types of narrowband and UWB antennas have been presented. The aim of this study is to understand the human body effects on the antenna parameters and specify the suitable antenna in BCWCs at both 2.45 GHz and UWB frequencies. Extensive experimental investigations are carried out to study the effects of various antenna types on the on-body radio propagation channels as well. Results and analysis emphasize the best body-worn antenna for reliable and power-efficient on-body communications. Based on the results and analysis, a novel dual-band and dual-mode antenna is proposed for power-efficient and reliable on-body and off-body communications. The on-body performance of the DBDM antenna at 2.45 GHz is compared with other five narrowband antennas. Based on the results and analysis of six narrowband and four UWB antennas, antenna specifications and design guidelines are provided that will help in selecting the best body-worn antenna for both narrowband and UWB systems to be applied in body-centric wireless networks (BCWNs). A comparison between IV the narrowband and UWB antenna parameters are also provided. At the end of the thesis, the subject-specificity of the on-body radio propagation channel at 2.45 GHz and 3-10 GHz was experimentally investigated by considering eight real human test subjects of different shapes, heights and sizes. The subject-specificity of the on-body radio propagation channels was compared between the narrowband and UWB systems as well