Over the coming decades, high-definition situationally-aware networks have the potential to create revolutionary applications in the social, scientific, commercial, and military sectors Ultrawide bandwidth (UWB) technology is a viable candidate for enabling accurate localization capabilities through time-of-arrival (TOA)-based ranging techniques These techniques exploit the fine delay resolution property of UWB signals by estimating the TOA of the first signal path Exploiting the full capabilities of UWB TOA estimation can be challenging, especially when operating in harsh propagation environments, since the direct path may not exist or it may not be the strongest In this paper, we first give an overview of ranging techniques together with the primary sources of TOA error (including propagation effects, clock drift, and interference) We then describe fundamental TOA bounds (such as the Cramer-Rao bound and the tighter Ziv-Zakai bound) in both ideal and multipath environments These bounds serve as useful benchmarks in assessing the performance of TOA estimation techniques We also explore practical low-complexity TOA estimation techniques and analyze their performance in the presence of multipath and interference using IEEE 802154a channel models as well as experimental data measured in indoor residential environments

/pdf/ranging-with-ultrawide-bandwidth-signals-in-multipath-illizjdvoz.pdf

Ranging With Ultrawide Bandwidth Signals in Multipath Environments

This paper presents an overview of ultrawideband (UWB) propagation channels. It first demonstrates how the frequency selectivity of propagation processes causes fundamental differences between UWB channels and "conventional" (narrowband) channels. The concept of pathloss has to be modified, and the well-known WSSUS model is not applicable anymore. The paper also describes deterministic and stochastic models for UWB channels, identifies the key parameters for the description of delay dispersion, attenuation, and directional characterization, and surveys the typical parameter values that have been measured. Measurement techniques and methods for extracting model parameters are also different in UWB channels; for example, the concepts of narrowband channel parameter estimation (e.g., maximum-likelihood estimation) have to be modified. Finally, channel models also have an important impact on the performance evaluation of various UWB systems.

Ultrawideband propagation channels-theory, measurement, and modeling

Antenna Theory And Design

Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. By Christophe Caloz and Tatsuo Itoh.

* The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The book presents sound coverage of the fundamentals of lightwave technology, along with material on pulse compression techniques and rare-earth-doped fiber amplifiers and lasers. The extensively revised chapters include information on fiber-optic communication systems and the ultrafast signal processing techniques that make use of nonlinear phenomena in optical fibers.New material focuses on the applications of highly nonlinear fibers in areas ranging from wavelength laser tuning and nonlinear spectroscopy to biomedical imaging and frequency metrology. Technologies such as quantum cryptography, quantum computing, and quantum communications are also covered in a new chapter.This book will be an ideal reference for: RD scientists involved with research on fiber amplifiers and lasers; graduate students and researchers working in the fields of optical communications and quantum information. * The only book on how to develop nonlinear fiber optic applications* Two new chapters on the latest developments; Highly Nonlinear Fibers and Quantum Applications* Coverage of biomedical applications

Applications of nonlinear fiber optics

The propagation of ultrawideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of UWB technology. The propagation of UWB signals is governed, among other things, by the properties of materials in the propagation medium. The information on electromagnetic properties of construction materials in the UWB frequency range would provide valuable insights into the appreciation of the capabilities and limitations of UWB technology. Although electromagnetic properties of certain construction materials over relatively narrow bandwidths in GHz frequency ranges are available, ultrawideband characterisation of most typical construction materials for UWB communication purposes has not been reported. In narrowband wireless communications, only the magnitude of insertion loss has been the quantity of interest. But for UWB signals, in addition to the magnitude, the phase information is an equally important factor that needs to be accounted for. In fact, UWB signals not only suffer attenuation when propagating through walls, but also suffer distortion due to the dispersive properties of the walls. This research examines propagation through typical construction materials and their ultrawideband characterisation. Ten commonly used construction materials are chosen for this investigation. Results for the dielectric constant and loss tangent of the materials over the UWB frequency range are presented. Accuracy of the measured results is discussed and distortions of UWB signals due to the dispersive properties of wall materials are addressed.

Ultrawideband through-the-wall propagation

The propagation of ultra wideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of the UWB technology and its applications. The objective of this work is to obtain a better assessment of the potentials of UWB indoor communications by characterizing the UWB indoor communication channels. Channel characterization refers to extracting the channel parameters from measured data. An indoor UWB measurement campaign is undertaken. Time-domain indoor propagation measurements using pulses with less than 100 ps width are carried out. Typical indoor scenarios, including line-of-sight (LOS), non-line-of-sight (NLOS), room-to-room, within-the-room, and hallways, are considered. Results for indoor propagation measurements are presented for local power delay profiles (local PDP) and small-scale averaged power delay profiles (SSA-PDP). Site-specific trends and general observations are discussed. The results for path-loss exponent and time dispersion parameters are presented.

Path-loss and time dispersion parameters for indoor UWB propagation

A comprehensive simulation of ultra-wideband signal propagation in indoor environments is presented. The simulation is based on time-domain electromagnetic modeling of transmitting and receiving antennas and the analysis of wave propagation through indoor channels using the time-domain uniform theory of diffraction. The antennas are a pair of TEM horns which are modeled as arrays of vee dipoles. The analysis of these antennas is performed directly in the time domain, without the need for transforming the solutions from the frequency domain to the time domain. The frequency dependence of materials utilized in the structure on the indoor channel is accounted for in the channel simulation. The simulation results are compared with the corresponding measured results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 103–108, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20221

Simulation of ultra‐wideband indoor propagation

Carbon nanotubes are characterized by slow wave propagation and high characteristic impedance due to the additional kinetic inductive efiect. This slow wave property can be used to introduce resonant dipole antennas with dimensions much smaller than traditional half-wavelength dipole in Terahertz band. However, this property has less efiect at lower frequency bands. This paper introduces the physical interpretation of this property based on the relation between the resonance frequency and the surface wave propagation constant on a carbon nanotube. This surface wave propagation is found to be characterized by high attenuation coe-cient at low frequency bands which limits using carbon nanotube as an antenna structure at these frequencies.

/pdf/lower-frequency-limit-of-carbon-nanotube-antenna-168eydmnd2.pdf

Lower frequency limit of carbon nanotube antenna

Preliminary experimental investigations on the application of UWB electromagnetic signals for through-wall detection are presented. Measurements are conducted using pulses with a full-width half-maximum (FWHM) nearly equal to 85 ps. This corresponds to a spatial resolution of about 26 mm. A simple signal processing approach is also introduced to extract the target image from the reflected fields.

http://ieeexplore.ieee.org/iel5/9253/29378/01332029.pdf

Ahmed M. Attiya

Papers

Ultrawideband through-the-wall propagation

Path-loss and time dispersion parameters for indoor UWB propagation

Simulation of ultra‐wideband indoor propagation

Lower frequency limit of carbon nanotube antenna

UWB applications for through-wall detection