This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

Metasurfaces: From microwaves to visible

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

Computer communications

A comprehensive review of the propagation prediction models for terrestrial wireless communication systems is presented in this paper. The classic empirical models are briefly described and the focus is placed on the application of ray-tracing techniques to the development of deterministic propagation models. Schemes to increase the computational efficiency and accuracy are discussed. Traditional statistical models are also briefly reviewed for completeness. New challenges to the propagation prediction are described and some new approaches for meeting these challenges are presented.

Propagation prediction models for wireless communication systems

This paper presents the program CINDOOR. This program is an engineering tool for aiding in the design, planning, and effective implementation of wireless systems in general enclosed spaces. The method underlying CINDOOR is a flexible approach to the propagation process, allowing analysis of indoor and outdoor environments and the interaction between them. The method is based on a full three-dimensional implementation of GO/UTD. Ray tracing is efficiently carried out by combining image theory with binary space partitioning algorithms. The space-time distribution of the electromagnetic field is processed to obtain a set of magnitudes that form a basis for planning a wireless system: coverage (mean power), fading statistics, power delay profile and associated parameters, such as the rms delay spread and the coherent bandwidth.

CINDOOR: an engineering tool for planning and design of wireless systems in enclosed spaces

The paper presents the RANURS code (radar cross section-NURBS surfaces) for the analysis of the monostatic radar cross section (RCS) of electrically large complex targets. The geometric representation of the targets is given in terms of parametric surfaces, which allow an excellent fit between the model and the real surface. The parametric surfaces used are NURBS (non-uniform rational B-spline) surfaces. This technique of modeling is used in many industries to represent complex bodies. Most of the CAGD (computer aided geometric design) tools use the NURBS format for modeling, because it can represent complicated objects using limited information. Therefore, an important feature of the code is its compatibility with most of the available CAGD codes, in order to ensure that the entire design process, involving different engineering aspects (structural, mechanical, aerodynamical, electrical, etc.) can be developed with compatible models. The scattered fields are calculated by using the physical optics and the equivalent currents methods (PO+ECM). The following contributions to the RCS are taken into account: reflected field, diffracted field, double-reflected field, and diffracted-reflected field. In addition, a method for determining the hidden parts of the targets is used. The PO+ECM approach is directly applied on the parametric surfaces, and the final expressions of the fields are given as functions of the coefficients of the numerical description of the NURBS patches.

Computation of the RCS of complex bodies modeled using NURBS surfaces

This paper provides the description and results of a recently developed statistical UWB multipath channel model. A new set of statistical parameters has been defined and obtained from a large measurement campaign process. The parameter values, a detailed model description and final results, are covered in this contribution.

New channel impulse response model for UWB indoor system simulations

This paper presents a multiple-input-multiple- output (MIMO) channel model based on rigorous ray-tracing techniques, which is based on a full 3-D implementation of geometric optics and the uniform theory of diffraction (3-D GO/ UTD). Results obtained from measurements and simulations of the correlation matrix and capacity of a 2 times 2 MIMO system in specific indoor environments at a frequency of 2 GHz are presented. The channel capacity has been calculated for the different local areas considered in open- and office-area scenarios, starting from the measurements carried out there, as well as from the ray-tracing simulated channels. The rigorous and quantitative comparison between measurements and simulations shows that the model accuracy is sufficient for the analysis and design of the different aspects of the full MIMO system. The results from the ray-tracing model can also be used to extract general statistical characteristics and parameterize statistical models for different types of environments, without the need to carry out large and costly measurement campaigns. In addition, the measured data are used to study the impact of the channel on the achievable capacity of a 2 times 2 MIMO system in typical indoor scenarios at 2 GHz.

Indoor MIMO Channel Modeling by Rigorous GO/UTD-Based Ray Tracing

Ray-tracing techniques have been widely used as simulation tools for the design and planning of wireless systems, both in urban microcells and in indoor picocells, due to the site-specific nature of those environments. However, the value of such tools depends on the accuracy of the predictions when compared to measurements in real-world propagation environments. In this paper, the accuracy of a ray-tracing technique based on a full three-dimensional implementation of GO/UTD is analyzed, by comparison between measurements and simulations carried out for different indoor wireless-propagation environments and in different frequency bands. The narrowband analysis shows that both the mean level of the received signal and the statistical behavior of its variations about the mean can be accurately estimated. In the wideband analysis, the comparison between measured and simulated power-delay profiles shows that both the amplitude and arrival times of the main multipath components can be well predicted. The statistical distributions of the measured and simulated wideband parameters are also compared, showing good agreement.

Rafael P. Torres

Papers

CINDOOR: an engineering tool for planning and design of wireless systems in enclosed spaces

Computation of the RCS of complex bodies modeled using NURBS surfaces

New channel impulse response model for UWB indoor system simulations

Indoor MIMO Channel Modeling by Rigorous GO/UTD-Based Ray Tracing

Accuracy analysis of GO/UTD radio-channel modeling in indoor scenarios at 1.8 and 2.5 GHz