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Intelligent walls as autonomous parts of smart indoor environments

This study introduces the concept of an intelligent wall as an autonomous part of a smart indoor environment for cognitive wireless networks. Here, an intelligent wall is a wall inside a building equipped with an active frequency-selective surface, simple low-cost sensors and a cognitive engine with machine-learning ability. Using simulations, it has been shown that the smart environment based on intelligent walls can react to the immediate demands of an indoor wireless system, control radio coverage and, consequently, influence the overall system performance. The concept of the intelligent walls is described and evaluated based on a simple implementation of an arrangement of two intelligent walls in a conference centre scenario. Artificial neural networks were employed in the cognitive engine. Elementary orthogonal frequency division multiple access static system simulations are used to analyse the influence of the smart environment on the system performance. Results are discussed in detail and typical characteristics of the aforementioned system are derived and summarised.

Advanced 3D indoor propagation model: calibration and implementation

A software tool, implementing a semi-deterministic model which provides swift predictions, accounts for all significant physical phenomena while utilising a clear-cut description of material properties, is presented in this article. The software can predict signal coverage, delay profiles and angle of arrivals for receivers located anywhere in a scenario using three probabilistic parameters to describe each of the materials. Probabilistic parameters can be efficiently optimised based on measured data by a genetic algorithm optimiser contained in the software tool enabling real material properties (constants) to be avoided. The semi-deterministic model is briefly described whereas its implementation into the tool is explained in greater detail. Measured narrowband, as well as wideband, data are presented, and the basic principles of the computer optimisation utilised in the tool are shown. Optimised results are compared with the measured ones and deviation is determined. The principle of a simple multi-threading algorithm which improves the tool performance while decreasing time consumption is presented along with computational times where a different number of threads are compared.

Controlling coverage for indoor wireless networks using Metalized Active FSS Walls

This paper presents a concept of an advanced method of controlling coverage for indoor wireless networks. The concept is based on the fact that electromagnetic wave propagation in indoor scenarios is mainly influenced by the propagation environment, e.g. walls, floors, ceilings, furniture etc. and such a propagation environment can be adjusted dynamically according to the current demands of the network by deploying what we call Active Frequency Selective Surface (AFFS) Walls. Using these walls, we are able to control the signal propagation at various frequencies, control the shape of covered area and limit interference. An example two-storey scenario acting as a small conference center is presented. The concept is verified by simulating simple Wi-Fi network and system of AFSS Walls. Advantages as well as potential problems of the proposed concept are discussed.

Semi-Deterministic Propagation Model for Subterranean Galleries and Tunnels

A three-dimensional, semi-deterministic model for wave propagation in subterranean galleries and tunnels is introduced. The model uses a combination of deterministic ray-launching techniques and a stochastic approach to provide efficient predictions that avoid complex calculations of electromagnetic phenomena while preserving the ability to consider reflection, absorption and penetration, as well as diffuse scattering. There is no need to provide a precise definition of the walls in terms of their material electrical parameters and roughness. The wall properties are efficiently described using just three probabilistic parameters that can be calibrated by measurements. Experimental data for three various subterranean scenarios were used to validate the models functionality. The scenarios were chosen with regard to validating the model function for different frequencies, cross-sections, lengths and shapes.

New Approach to Modeling of Diffuse Reflection and Scattering for Millimeter-wave Systems in Indoor Scenarios

A new approach to modeling difiuse re∞ection and scattering for millimeter-wave band based on a fast and simple semi-deterministic principle is presented. The model is based on the combination of pre-computed radiation patterns and a fast semi-deterministic algorithm. The principle and function of this model are explained as well as tested in a common indoor scenario represented by a room equipped with furniture. The results obtained through simulations are compared with results received from a classical ray-based model and signiflcant difierences are discussed in detail.

Intelligent RF Wall Unit for in-building WLAN applications

This paper presents the design and characterization of an Intelligent Wall Unit (IWU) for use in in-building WLAN applications. The IWU comprises of a pair of patch antennas connected via a wirelessly controlled RF switching circuit. The antennas are placed either side of a semi-shielded wall to allow Wi-Fi signals to be “switched” on or off depending on wireless network traffic. The prototype system is characterized using Zigbee wireless nodes measuring the RF power in a two way communications link implemented in a representative intelligent room. It is shown that the RF power can be changed by up to 20dB with the IWU switched on or off.

An Evaluation of Approaches for Modeling of Terrestrial, HAP and Satellite Systems Performance during Rain Events

This paper presents the results from site-specific simulations of route diversity performance in case of High Altitude Platform system, terrestrial system and satellite system during specific rain events. Based on the radar rainfall database, route diversity dependences on altitude of transmitter were studied using the simulation tool. The main goal of the paper is to adopt concept for HAP systems from investigations of both terrestrial point-to-multipoint systems and satellite systems operating in millimeter frequency bands.