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

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

In classification, feature selection is an important data pre-processing technique, but it is a difficult problem due mainly to the large search space. Particle swarm optimisation (PSO) is an efficient evolutionary computation technique. However, the traditional personal best and global best updating mechanism in PSO limits its performance for feature selection and the potential of PSO for feature selection has not been fully investigated. This paper proposes three new initialisation strategies and three new personal best and global best updating mechanisms in PSO to develop novel feature selection approaches with the goals of maximising the classification performance, minimising the number of features and reducing the computational time. The proposed initialisation strategies and updating mechanisms are compared with the traditional initialisation and the traditional updating mechanism. Meanwhile, the most promising initialisation strategy and updating mechanism are combined to form a new approach (PSO(4-2)) to address feature selection problems and it is compared with two traditional feature selection methods and two PSO based methods. Experiments on twenty benchmark datasets show that PSO with the new initialisation strategies and/or the new updating mechanisms can automatically evolve a feature subset with a smaller number of features and higher classification performance than using all features. PSO(4-2) outperforms the two traditional methods and two PSO based algorithm in terms of the computational time, the number of features and the classification performance. The superior performance of this algorithm is due mainly to both the proposed initialisation strategy, which aims to take the advantages of both the forward selection and backward selection to decrease the number of features and the computational time, and the new updating mechanism, which can overcome the limitations of traditional updating mechanisms by taking the number of features into account, which reduces the number of features and the computational time.

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Particle swarm optimisation for feature selection in classification

A system and method for design, tracking, measurement, prediction and optimization of data communications networks includes a site specific model of the physical environment, and performs a wide variety of different calculations for predicting network performance using a combination of prediction modes and measurement data based on the components used in the communications networks, the physical environment, and radio propagation characteristics.

System and method for design, tracking, measurement, prediction and optimization of data communication networks

Wireless vehicular networks operating on the dedicated short-range communications (DSRC) frequency bands are the key enabling technologies for the emerging market of intelligent transport system (ITS). The wireless access in vehicular environments (WAVE) is significantly different from the Wi-Fi and cellular wireless networking environments. The specifications defined by IEEE802.11P and IEEE1609 represent the most mature set of standards for DSRC/WAVE networks. This paper provides an overview of the current state of the art, and analyses the potential differences between application requirements and what can be offered by the current WAVE solutions. It is shown that the current solutions may be inadequate for large-scale deployment. The primary challenge is to develop scalable, robust, low-latency and high-throughput technologies for safety applications that will significantly reduce collisions and save lives and property loss. Further research ideas are proposed to address this challenge.

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An Overview of the DSRC/WAVE Technology

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

Ray-tracing techniques have proven to be very useful for the analysis and design of wireless systems both in urban microcells and in indoor picocells. At present, the optimization of these techniques enables not only the signal mean level but also the local statistics to be estimated accurately, which is of great practical importance. A wide range of comparisons between measurements and simulations confirming this have been carried out by the authors, and some examples are presented. The most interesting contribution of this paper is that starting from the signal information at one single point, obtained using ray-tracing techniques, it is possible to estimate the signal statistics in a local area of that point. This possibility substantially reduces the local statistics calculation time, confirming the idea that an efficient site specific channel model might be feasible. Finally, it is also shown that ray-tracing techniques are able to accurately estimate the first- and second-order statistics in those environments where the Clarke (1968) or isotropic scattering model is not applicable.

An accurate and efficient method based on ray-tracing for the prediction of local flat-fading statistics in picocell radio channels

A new and efficient ray-tracing method based on a combination of image theory and the binary space partitioning (BSP) algorithm is presented. The efficiency of the method allows a full three-dimensional implementation of the Geometrical Optics and the Uniform Theory of Diffraction (GO/UTD). The optimization of ray-tracing makes it possible to take into account a great number of rays: reflected, diffracted and multiple combinations of these effects. This degree of precision in the calculation of the signal levels permits an accurate estimation not only of the signal mean level but also its statistics. The main feature of the method is the possibility of analyzing the radio channel in general enclosed spaces, including indoor, outdoor and mixed indoor/urban environments.

An efficient ray-tracing method for radiopropagation based on the modified BSP algorithm

Population-based optimization algorithms are widely used in multiple research areas to optimize different kinds of problems. Commonly, they have been successfully applied to low and medium size search spaces in order to tune or adjust several design parameters. Unfortunately, population-based algorithms can require too much CPU time to find a nearly optimal solution as the number of dimensions of the problem to tackle increases significantly. Usually, mathematical or physical-inspired techniques have been applied to improve the success rate as well as the speed of convergence of population-based methods in a high dimensional framework. An alternative choice is to allocate the individuals of the population in an efficient way during the initialization stage of the algorithm considering two possibilities: placing individuals as close as possible to a global optimum or uniformly distributed over the search space. In this work, three different initialization strategies, the orthogonal array initialization, a chaotic technique and the opposition based initialization have been considered and appropriately combined with the heuristic particle swarm optimization (PSO) algorithm. Results comparing the modified PSO algorithm when applied to optimize frequency selective surfaces (FSS) and planar arrays for WiMAX applications are included.

M. Domingo

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

An accurate and efficient method based on ray-tracing for the prediction of local flat-fading statistics in picocell radio channels

An efficient ray-tracing method for radiopropagation based on the modified BSP algorithm

Comparison of different PSO initialization techniques for high dimensional search space problems: A test with FSS and antenna arrays