Indoor wireless communications and applications

Chapter 3 addresses challenges in radio link and system design in indoor scenarios. Given the fact that most human activities take place in indoor environments, the need for supporting ubiquitous indoor data connectivity and location/tracking service becomes even more important than in the previous decades. Specific technical challenges addressed in this section are(i), modelling complex indoor radio channels for effective antenna deployment, (ii), potential of millimeter-wave (mm-wave) radios for supporting higher data rates, and (iii), feasible indoor localisation and tracking techniques, which are summarised in three dedicated sections of this chapter

Performance analysis of ultra wide band indoor channel

This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Computer Science and Engineering, 2008.Cataloged from PDF version of thesis report.Includes bibliographical references (page 41).Research on wireless communication system has been pursued for many years, but there is a renewed interest in ultra-wideband (UWB) technology for communication within short range, because of its huge bandwidth and low radiated power level. This emerging technology provides extremely high data rate in short ranges but in more secured approach. In order to build systems that realize all the potential of UWB, it is first required to understand UWB propagation and the channel properties arise from the propagation. In this research, the properties of UWB channel for indoor industrial environment was evaluated. A few indoor channel models have been studied so far for different environments but not for indoor industrial environment and various data rates are obtained according to wireless channel environments. Therefore, an accurate channel model is required to determine the maximum achievable data rate. In this thesis, we have proposed a channel model for indoor industrial environment considering the scattering coefficient along with the other multipath gain coefficient. This thesis addresses scattering effect while modeling UWB channel. Here, the performance of UWB channel model is analyzed following the parameters, such as power delay profile and the temporal dispersion properties which are also investigated in this paper.Kazi Afrina YasmeenA. K. M. WahiduzzamanMD. Ahamed ImtiazB. Computer Science and Engineerin

Real-time signal detection and classification algorithms for body-centered systems

El principal motivo por el cual los sistemas de comunicación en el entrono corporal se desean con el objetivo de poder obtener y procesar señales biométricas para monitorizar e incluso tratar una condición médica sea ésta causada por una enfermedad o el rendimiento de un atleta. Dado que la base de estos sistemas está en la sensorización y el procesado, los algoritmos de procesado de señal son una parte fundamental de los mismos. Esta tesis se centra en los algoritmos de tratamiento de señales en tiempo real que se utilizan tanto para monitorizar los parámetros como para obtener la información que resulta relevante de las señales obtenidas. En la primera parte se introduce los tipos de señales y sensores en los sistemas en el entrono corporal. A continuación se desarrollan dos aplicaciones concretas de los sistemas en el entorno corporal así como los algoritmos que en las mismas se utilizan. La primera aplicación es el control de glucosa en sangre en pacientes con diabetes. En esta parte se desarrolla un método de detección mediante clasificación de patronones de medidas erróneas obtenidas con el monitor contínuo comercial "Minimed CGMS". La segunda aplicacióin consiste en la monitorizacióni de señales neuronales. Descubrimientos recientes en este campo han demostrado enormes posibilidades terapéuticas (por ejemplo, pacientes con parálisis total que son capaces de comunicarse con el entrono gracias a la monitorizacióin e interpretación de señales provenientes de sus neuronas) y también de entretenimiento. En este trabajo, se han desarrollado algoritmos de detección, clasificación y compresión de impulsos neuronales y dichos algoritmos han sido evaluados junto con técnicas de transmisión inalámbricas que posibiliten una monitorización sin cables. Por último, se dedica un capítulo a la transmisión inalámbrica de señales en los sistemas en el entorno corporal. En esta parte se estudia las condiciones del canal que presenta el entorno corporal para la transmisión de sTraver Sebastiá, L. (2012). Real-time signal detection and classification algorithms for body-centered systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16188Palanci

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

A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

In recent years, there has been a dramatic increase in the use of unmanned aerial vehicles (UAVs), particularly for small UAVs, due to their affordable prices, ease of availability, and ease of operability. Existing and future applications of UAVs include remote surveillance and monitoring, relief operations, package delivery, and communication backhaul infrastructure. Additionally, UAVs are envisioned as an important component of 5G wireless technology and beyond. The unique application scenarios for UAVs necessitate accurate air-to-ground (AG) propagation channel models for designing and evaluating UAV communication links for control/non-payload as well as payload data transmissions. These AG propagation models have not been investigated in detail when compared to terrestrial propagation models. In this paper, a comprehensive survey is provided on available AG channel measurement campaigns, large and small scale fading channel models, their limitations, and future research directions for UAV communication scenarios

Detection of PPM-UWB random signals

This paper focuses on the symbol detection problem of random pulse-position modulation (PPM) ultrawideband (UWB) signals in the absence of interframe interference. Particular attention is devoted to severely time-varying channels where optimal detectors are proposed for both uncorrelated and correlated scattering scenarios. This is done by assuming the received waveforms to be unknown parameters. In UWB communication systems, the assumption of unknown random waveforms is consistent with the fact that the received waveform has very little resemblance with the original transmitted pulse. In order to circumvent this limitation, a conditional approach is presented herein by compressing the likelihood ratio test with the information regarding the second-order moments of the end-to-end channel response. Both full-rank and rank-one detectors are derived. For the reduced complexity rank-one detector, an iterative procedure is presented that maximizes the J-divergence between the hypotheses to be tested. Finally, simulation results are provided to compare the performance of the proposed detectors in different propagation environments.Peer Reviewe

UWB Indoor Radio Propagation Modelling in Presence of Human Body Shadowing Using Ray Tracing Technique

This paper presents a ray-tracing method for modelingUltra Wide Bandwidth indoor propagation channels. Avalidation of the ray tracing model with our indoor measurementis also presented. Based on the validated model, the multipathchannel parameter like the fading statistics and root mean squarerms delay spread for Ultra Wide bandwidth frequencies aresimply extracted. The proposed ray-tracing method is basedon image method. This is used to predict the propagation ofUWB electromagnetic waves. First, we have obtained that thefading statistics can be well fitted by log normal distributionin static case. Second, as in realistic environment we cannotneglect the significant impact of Human Body Shadowing andother objects in motion on indoor UWB propagation channel.Hence, our proposed model allows a simulation of propagationin a dynamic indoor environment. Results of the simulation showthat this tool gives results in agreement with those reported inthe literature. Specially, the effects of people motion on temporalchannel properties. Other features of this approach also areoutlined

Ultra-Wideband Wireless Channels - Estimation, Modeling and Material Characterization

This licentiate thesis is focused on the characterization of ultra-wideband wireless channels. The thesis presents results on ultra-wideband communications as well as on the ultra-wideband characterization of materials. The communications related work consisted in the measurement and modeling of outdoor scenarios envisioned for infostation systems. By infostation, we mean a communication system covering a small area, i.e., ranging up to 20 m, where mobile users can pass by or stop while receiving large amounts of data in a short period of time. Considering the expected (but perhaps overly optimistic) 480 Mbps for UWB systems, it should be possible to download a complete DVD in roughly two minutes, which is something not realizable with any of the current wireless technologies. Channel models, commonly based on measurements, can be used to evaluate the performance of such systems. We therefore, we started by performing measurements at one of the scenarios where infostation systems can exist in the future, namely, petrol stations. The idealized model, was one that could correctly describe the continuous evolution of the channel impulse response for a moving user within the system’s range, and therefore it was deemed necessary to track the multipath components defining the impulse responses along a path of several meters. To solve this problem we designed a novel high-resolution scatterer detection method, which is described in Paper I, capable of tracking individual multipath components for a moving user by identifying the originating point scatterers in a two dimensional geometrical space. The same paper also gives insight on some properties of clusters of scatterers, such as their direction-selective radiated power. The scatterer detection method described in Paper I provided us with the required tools to create the channel model described in Paper II. The proposed channel model has a geometrical basis, i.e., each realization of the channel is based on a virtual map containing point scatterers that contribute to the impulse response by multipath components. Some of the particular characteristics of the model include non-stationary effects, such as shadowing and cluster’s visibility regions. At the end of Paper II, in a simple validation step, the output of the channel model showed a good match with the measured impulse responses. The second part of our work, documented in Paper III, consisted on the dielectric characterization of soil samples using microwave measurements. This project was made in cooperation with the Department of Physical Geography and Ecosystem Analysis at Lund University, which had been developing research work on methane emissions from the wetlands in Zackenberg, Greenland. In recent years, a lot of attention has been put into the understanding of the methane emissions from soils, since methane is a greenhouse gas 20 times stronger than carbon dioxide. However, whereas the methane emissions from natural soils are well documented, the reason behind this effect is an open issue. The usage of microwave measurements to monitor soil samples, aims to address this problem by capturing the sub-surface changes in the soil during gas emissions. An experiment consisting on the monitoring of a soil sample was performed, and a good correlation was found between the variations of the microwave signals and the methane emissions. In addition, the soil dielectric constant was calculated, and from that, the volumetric fractions of the soil constituents which provided useful data for the elaboration of models to describe the gas emission triggering mechanisms. Based on this laboratory experiment, a complete soil monitoring system was created and is at the time of writing running at Zackenberg, Greenland