Closed-Form Approximation for Parallel-Plate Waveguide Coefficients

Simple closed-form formulas for calculating coefficients of modes excited in a parallel-plate waveguide illuminated by a planar wave are presented. The mode-matching technique and Green’s formula are used to arrive at a matrix-based expression for waveguide coefficients calculation. Simplified solution to this matrix is proposed to derive approximate mode coefficient formulas in closed-form for both TE and TM polarization. The results are validated by numerical simulations and show good accuracy for all incidence angles and in broad frequency range

A Correlation between RSSI and Height in UHF Band and Comparison of Geolocation Spectrum Database View of TVWS with Ground Truth.

An investigation into the Received Signal Strength Indica- tor (RSSI) dependency on receiver antenna height in UHF band is con- ducted. The results show a high correlation between RSSI and height on channels with high signal strength. There is approximately 2.5 dBm RSSI gain per 1 m increase in height above ground up to 8.5 m. From 8.5 m to 12 m, there is no consistent observable increase in RSSI. Further- more, the geolocation spectrum databases (GLSD) view of white space in the television band is compared with the ground truth. Results show signal presence on some of the channels indicated free by the spectrum database. These findings imply that an increase in transmission range of UHF links can be achieved by increasing receiver height. White space devices using A GLSD should additionally require spectrum scanning to determine clear channels

Map-Aware Models for Indoor Wireless Localization Systems: An Experimental Study

The accuracy of indoor wireless localization systems can be substantially enhanced by map-awareness, i.e., by the knowledge of the map of the environment in which localization signals are acquired. In fact, this knowledge can be exploited to cancel out, at least to some extent, the signal degradation due to propagation through physical obstructions, i.e., to the so called non-line-of-sight bias. This result can be achieved by developing novel localization techniques that rely on proper map-aware statistical modelling of the measurements they process. In this manuscript a unified statistical model for the measurements acquired in map-aware localization systems based on time-of-arrival and received signal strength techniques is developed and its experimental validation is illustrated. Finally, the accuracy of the proposed map-aware model is assessed and compared with that offered by its map-unaware counterparts. Our numerical results show that, when the quality of acquired measurements is poor, map-aware modelling can enhance localization accuracy by up to 110% in certain scenarios.Comment: 13 pages, 11 figures, 1 table. IEEE Transactions on Wireless Communications, 201

Prog Electromagn Res C Pier C

Understanding wireless channels in complex mining environments is critical for designing optimized wireless systems operated in these environments. In this paper, we propose two physics-based, deterministic ultra-wideband (UWB) channel models for characterizing wireless channels in mining/tunnel environments - one in the time domain and the other in the frequency domain. For the time domain model, a general Channel Impulse Response (CIR) is derived and the result is expressed in the classic UWB tapped delay line model. The derived time domain channel model takes into account major propagation controlling factors including tunnel or entry dimensions, frequency, polarization, electrical properties of the four tunnel walls, and transmitter and receiver locations. For the frequency domain model, a complex channel transfer function is derived analytically. Based on the proposed physics-based deterministic channel models, channel parameters such as delay spread, multipath component number, and angular spread are analyzed. It is found that, despite the presence of heavy multipath, both channel delay spread and angular spread for tunnel environments are relatively smaller compared to that of typical indoor environments. The results and findings in this paper have application in the design and deployment of wireless systems in underground mining environments.CC999999/Intramural CDC HHS/United States2018-02-14T00:00:00Z29457801PMC5812029vault:2734

UHF band short range propagation model

The final publication is available at Springer via http://dx.doi.org/10.1007/s11277-013-1188-7The purpose of this study is to characterize the indoor and indoor–outdoor propagation in different scenarios, using monopole antennas working at 410 and 890 MHz. Propagation of narrow band and wide bands have been studied. In scenarios with a continuous variation of the distance between the transmitter and receiver antenna (1 D scenarios), we use a log-distance path loss model to determine the equations that describe the mean value of the path loss. In scenarios where the position of the receiver is not a uniform function of the distance between the transmitter and the receiver, we represent the basic propagation gain as a function of the measurement point index. Results show that the indoor propagation gain can be described using two slopes propagation model. For the multiwall attenuation loss it is shown that each wall has an attenuation of almost 2.5 dB at 410 MHz increasing to almost 4 dB at 890 MHz. The obstruction gain (loss) due to human beings shows that this can be within a 40 dB interval

Comparing Downlink Capacity between Super Wi-Fi and Wi-Fi in Multi-Floored Indoor Environments

Department of Electrical EngineeringSuper Wi-Fi is a Wi-Fi-like service exploiting TV white spaces (WS) via the cognitive radio technology which is expected to achieve larger coverage than today???s Wi-Fi thanks to its superior propagation characteristics. Super Wi-Fi is currently being materialized as an international standard, IEEE 802.11af, targetting indoor and outdoor applications. This thesis demonstrates the potential of Super Wi-Fi in indoor environments by measuring its signal propagation characteristics and comparing them with those of Wi-Fi in the same indoor structure. Specifically, this thesis measures the wall and floor attenuation factors and path-loss distribution in 770 MHz and 2.4 GHz, and estimates the downlink capacity of Super Wi-Fi and Wi-Fi according to wide-accepted indoor path loss models. The experimental results reveal that TVWS signals can penetrate up to two floors and provide favorable coverage up to one floor above and below. In addition, TVWS can not only extend the coverage of Wi-Fi but also significantly mitigate shaded regions of Wi-Fi while achieving almost homogeneous data rates in the Wi-Fi???s coverage. The observed phenomena imply that Super Wi-Fi may be suitable for indoor applications with requirements of low-to-moderate data rates, extended horizontal and vertical coverage, and fair rate distribution within the service coverage.ope

A Comprehensive Overview and Characterization of Wireless Channels for Networked Robotic and Control Systems

The goal of this overview paper is to serve as a reference for researchers that are interested in the realistic modeling of wireless channels for the purpose of analysis and optimization of networked robotic systems. By utilizing the knowledge available in the wireless communication literature, we first summarize a probabilistic framework for the characterization of the underlying multiscale dynamics of a wireless link. We furthermore confirm this framework with our robotic testbed, by making an extensive number of channel measurements. To show the usefulness of this framework for networked robotic applications, we then discuss a few recent examples where this probabilistic channel characterization has been utilized for the theoretical analysis and communication-aware design of networked robotic systems. Finally, we show how to develop a realistic yet simple channel simulator, which can be used to verify cooperative robotic operations in the presence of realistic communication links

Enhancing wireless communication system performance through modified indoor environments

This thesis reports the methods, the deployment strategies and the resulting system performance improvement of in-building environmental modification. With the increasing use of mobile computing devices such as PDAs, laptops, and the expansion of wireless local area networks (WLANs), there is growing interest in increasing productivity and efficiency through enhancing received signal power. This thesis proposes the deployment of waveguides consisting of frequency selective surfaces (FSSs) in indoor wireless environments and investigates their effect on radio wave propagation. The received power of the obstructed (OBS) path is attenuated significantly as compared with that of the line of sight (LOS) path, thereby requiring an additional link budget margin as well as increased battery power drain. In this thesis, the use of an innovative model is also presented to selectively enhance radio propagation in indoor areas under OBS conditions by reflecting the channel radio signals into areas of interest in order to avoid significant propagation loss. An FSS is a surface which exhibits reflection and/or transmission properties as a function of frequency. An FSS with a pass band frequency response was applied to an ordinary or modified wall as a wallpaper to transform the wall into a frequency selective (FS) wall (FS-WALL) or frequency selective modified wall (FS-MWALL). Measurements have shown that the innovative model prototype can enhance 2.4GHz (IEEE 802.11b/g/n) transmissions in addition to the unmodified wall, whereas other radio services, such as cellular telephony at 1.8GHz, have other routes to penetrate or escape. The FSS performance has been examined intensely by both equivalent circuit modelling, simulation, and practical measurements. Factors that influence FSS performance such as the FSS element dimensions, element conductivities, dielectric substrates adjacent to the FSS, and signal incident angles, were investigated. By keeping the elements small and densely packed, a largely angle-insensitive FSS was developed as a promising prototype for FSS wallpaper. Accordingly, the resultant can be modelled by cascading the effects of the FSS wallpaper and the ordinary wall (FSWALL) or modified wall (FS-MWALL). Good agreement between the modelled, simulated, and the measured results was observed. Finally, a small-scale indoor environment has been constructed and measured in a half-wave chamber and free space measurements in order to practically verify this approach and through the usage of the deterministic ray tracing technique. An initial investigation showing that the use of an innovative model can increase capacity in MIMO systems. This can be explained by the presence of strong multipath components which give rise to a low correlated Rayleigh Channel. This research work has linked the fields of antenna design, communication systems, and building architecture