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The objective of this special issue is to publish papers related to the basic physics of Electromagnetism in thecontext of radio wave propagation, see editorial of Part I. [ABSTRACT FROM AUTHOR]

This paper summarizes the lessons learned using a physics-based macromodel in studying electromagnetic wave propagation over an imperfectly conducting ground in cellular wireless communication. First, it has been observed that the path loss exponent is independent of the nature of the ground parameters inside the cell of interest. Second, the electrical parameters of the environment have little effect on the path loss exponent in the cellular band. Third, it is observed that lowering the base station antenna toward the ground provides a stronger signal in the near field within the cell of interest. Furthermore, tilting the transmitting antenna toward the sky enhances the signal strength. Tilting the antenna toward the ground increases the signal strength but, in addition, enhances the interference pattern and, hence, is not a good solution. A typical path loss inside the cell is 30 dB per decade of distance, and outside the cell, it increases to 40 dB per decade. By bringing the antenna closer to the ground and then tilting it toward the sky, a good nonintuitive solution is provided. In such scenarios, a path loss of 20 dB per decade for some components of the field, the lowest possible, can be achieved for certain orientations and deployment of the base station antenna. In addition, it is shown that operating an antenna inside a metallic box eliminates its radiation capabilities and, hence, has no physical meaning even though it is claimed in the contemporary literature that it simulates a rich multipath environment. Finally, a note on the proper interpretation of the term channel capacity and its implications is delineated. [ABSTRACT FROM AUTHOR]

This paper presents a physics-based macro model that can predict with a high degree of accuracy various experimental data available for the propagation path loss of radio waves in a cellular wireless environment. A theoretical macro model based on the classical Sommerfeld formulation can duplicate various experimental data including that of Okumuraet al.carried out in 1968. It is important to point out that there are also many statistical models but they do not conform to the results of the available experimental data. Specifically, there are separate path loss propagation models available in the literature for waves traveling in urban, suburban, rural environments, and the like. However, no such distinction is made in the results obtained from the theoretical analysis and measured experimental data. Based on the analysis using the macro model developed after Sommerfeld’s classic century-old analytical formulation, one can also explain the origin of slow fading which is due to the interference between the direct wave from the base station antenna and the ground wave emanating from the reflections of the direct wave and occurs only in the near field of the transmitting antenna. The so-called height gain occurs in the far field of a base station antenna deployment which falls generally outside the cell of interest, while in the near field, within the cell, there is a height loss of the field strength for observation points near the ground. A physical realization of the propagation mechanism is illustrated through Vander Pol’s exact transformation of the Sommerfeld integrals for the potential to a spatial semiinfinite volume integral and thus illustrates why buildings, trees, and the like have little effects on the propagation mechanism. [ABSTRACT FROM AUTHOR]

This paper provides a survey of various experimental data available on the value of the propagation path loss of radio waves in a cellular wireless environment. It is shown starting with the Okumuraet al.’s paper on propagation measurements and other available published experimental data that they all exhibit that the electric field varies as $\rho ^{-1.5}$ within a cellular radius of a few kilometers, where $\rho $ is the radial distance of the receiving antenna from the transmitting one. This decay in the fields is equivalent to a propagation loss of −9 dB/octave or −30 dB for a decade of the distance. This value is independent of the nature of the ground, whether it be composed of rural, urban, suburban, or water. This is the first time it is stated that the propagation path loss due to the presence of ground generates a path loss of 90 dB when the signals travel a distance of 1 km. This value is rather large when compared to a loss of 30–50 dB produced by buildings, trees, and similar artifacts. Therefore, the experimental data indicate that the effect of trees and buildings have a secondary influence on the decay of the electric field with distance, the dominant one is the propagation loss over an imperfect ground. Contemporary propagation models do not acknowledge this fact. Outside the cellular radius of a few kilometers, the path loss appears to be 12 dB/octave or 40 dB/decade of distance. In a companion paper, it will be demonstrated that the values for the path loss can be explained from an analytical standpoint without taking recourse to statistics which involves a lot of assumptions on the functional variation of the variables of interest. [ABSTRACT FROM AUTHOR]

Physics-based wireless propagation modeling and network protocol design have evolved over decades as orthogonal areas in communication systems research. This fragmented approach does not exploit available efficiencies when planning and deploying communication systems. In an attempt to integrate the two areas, we harness the understanding of the underlying physics of electromagnetic propagation to enhance the robustness of network protocol design by deriving physics-based network-level performance metrics. We use ray-tracing and parabolic equation models of 2.4 GHz propagation along tunnel and open-air sections of London Underground to evaluate the performance of a communications-based train control system. For comparison, we consider existing path loss models for tunnel environments and investigate whether they can provide sufficient accuracy to be used for network protocol design. We show that physics-based models lead to reliable predictions at the network level, similar in fidelity to using measured data and unlike using simplified channel models of the path loss exponent type. [ABSTRACT FROM AUTHOR]

A test setup is deployed to study the influence of base station antenna height on the cellular network coverage. Both the numerical and experimental investigations are undertaken to evaluate the received electric field levels for different heights of the transmitting (TX) antenna and several distances between the transmitter and the receiver. The numerical simulation results demonstrate that when the TX antenna is mounted high above the ground, more fluctuations are induced in the electric field levels, resulting in possible dead zones for mobile communications. The measured received levels and data rates confirm the numerical simulation results. [ABSTRACT FROM AUTHOR]

Wireless communications are expected to take place in increasingly complicated scenarios, such as dense urban, forest, tunnel, and other cluttered environments. A key emerging challenge is to understand the physics and characteristics of wave propagation in these environments, which is critical for the analysis, design, and application of advanced mobile and wireless communication systems. In this paper, we present a full-wave field-based computational methodology for radio wave propagation in complex urban environments. Both transmitting/receiving antennas and propagation environments are modeled by first-principles calculations. A system-level, large scene analysis is enabled by the scalable, ultraparallel algorithms on the emerging high-performance computing platforms. The proposed computational framework is verified and validated with semianalytical models and representative measurements. [ABSTRACT FROM AUTHOR]

Fixed performing antennas are ineffective in providing optimum performance in a changing multipath environment, such as underground mines where channel conditions quickly change as the antenna is moved. Hence, we investigated the performance of a pattern reconfigurable antenna (RA) in improving the wireless communications link in a hard rock underground mine. An RA and a dipole were characterized and compared in line-of-sight (LOS) and nonline-of-sight (NLOS) propagation scenarios. As a proof of concept, experiments were performed at the University of Queensland Experimental Mine using a 1 GHz frequency band centered at 2.45 GHz. Analysis of complex channel impulses captured through the frequency-domain channel sounding is presented. Also, the results show that reconfigurability in the rich multipath environment achieves a 20% and 34% improvement in path loss and delay spread, respectively, compared to a fixed-beam antenna in NLOS propagation. Furthermore, more than 34% improvement in coherence bandwidth is observed in LOS and NLOS. Therefore, reliable high-data-rate communication is achievable in underground mines by the effective management of multipath effects using the RA. [ABSTRACT FROM AUTHOR]

Fabry–Perot (FP)/leaky-wave antennas fed with multiple sources are analyzed and modeled. A transmission line (TL) approach for a rapid and efficient analysis of such antenna configuration is developed. The method is based on the superposition of the traveling leaky waves excited by each of the applied sources. The field distribution inside the cavity is derived by using a longitudinal TL model which takes into account the interference of the multiple leaky waves excited by the sources. The radiation pattern of the multiple fed antennas is obtained by using the fast Fourier transformation of the field distribution. The propagation constants of the leaky waves, traveling inside the FP cavity, are computed analytically, and the accuracy of the proposed expressions is verified by using the transverse resonance method approach. A novel and accurate closed-form expression for the leaky-wave propagation constant has been derived. A detailed analysis of the antenna properties is carried out by using the model showing how this antenna configuration is suitable for designing very large aperture antennas with very high gain and fairly acceptable bandwidth. A prototype of a multifeed FP antenna has been fabricated by using 3-D printing technology and tested. [ABSTRACT FROM AUTHOR]

When reverberation chambers are loaded to increase the coherence bandwidth for modulated-signal measurements, a secondary effect is decreased spatial uniformity. We show that an appropriate choice of stirring sequence, consisting of a combination of mode-stirring mechanisms such as paddle and antenna-platform stirring, can mitigate the potential for increased uncertainty. We develop a new mode-stirring sample correlation model for uncertainty due to the stirring sequence. In a comparison with an empirical uncertainty analysis, the model is found to have an agreement within 2.5%. Our analysis is demonstrated for four loading cases in each of three reverberation chambers. The model is used to determine an optimal stirring sequence for a given chamber setup directly from correlations associated with each stirring mechanism. The model can also be understood in terms of the entropy of a measurement and it is shown that maximizing the entropy corresponds to a minimized uncertainty. The method presented here not only provides insight into sources of uncertainty but also allows users to determine an optimal mode-stirring sequence with minimized uncertainty for a given chamber setup. [ABSTRACT FROM AUTHOR]

The radiowave propagation through hollow clay brick walls, which are common in southern European construction, is analyzed. The brick walls have thicknesses of 11, 15, and 20 cm, common in both interior and exterior walls, and are bound with a portland cement, water, and sand mixture. For each brick dimension, three prototypes were assembled, varying in the type of wall finish, i.e., exposed brick, smooth painted plaster, and rough painted plaster. A 10 cm concrete wall was also included for comparison purposes. Penetration loss metrics were evaluated in an anechoic chamber at frequencies ranging from 680 MHz to 10 GHz. Results demonstrate that the brick wall internal heterogeneity, as well as the type of finish, significantly influences the propagation phenomena and thus the frequency response of the walls, with relatively high penetration losses observed at some relevant commercial frequency bands. Finally, an alternative brick design, with reduced penetration losses, is also proposed and evaluated under simulation environment only. [ABSTRACT FROM AUTHOR]

Wireless communications or navigation is heavily influenced by electromagnetic wave propagation. The power-delay profile (PDP) characterizes the propagation channel by simple statistics. In this communication, we propose a channel model to simulate a given wideband averaged PDP obtained by measurements or theoretical considerations, enabling to test, develop, and design radio links. The channel model is based on a geometrical stochastic approach, allowing to simulate the space-variant channel impulse response for a moving receiver. Furthermore, the appearance and disappearance of multipath components are geometrically taken into account by an angular pattern. We verify the proposed methodology by simulations. [ABSTRACT FROM AUTHOR]

ATMospheric simulator for PROPagation applications (ATM PROP), a comprehensive methodology to assess tropospheric effects affecting high-frequency earth–space communication systems, is presented. The model takes advantage of physically based approaches aimed at synthesizing high-resolution (1 km $\times1$ km horizontal, 100-m vertical) 3-D fields of rain, clouds, and water vapor (dimension: 200 km $\times200$ km horizontal, 20-km vertical), which are all merged so as to maintain their mutual correlation. This, in turn, enables a more realistic combination of the attenuation due to single constituents, if compared to the statistical approach currently recommended by the ITU-R. The accuracy of ATM PROP in predicting tropospheric effects on earth–space systems is initially validated against the large propagation data set collected at the experimental station of Spino d’Adda, Italy, during the ITALSAT propagation campaign. The preliminary results obtained suggest that ATM PROP can be used to predict, with a reasonable level of complexity and limited coarse-resolution Numerical Weather Prediction-derived inputs, the tropospheric fade affecting complex communication systems (e.g., site diversity schemes), especially those involving low elevation links (e.g., low earth orbit or geostationary orbit at high latitude), for which the spatial distribution of the relevant tropospheric constituents needs to be taken in due account. [ABSTRACT FROM AUTHOR]

The next generation of intelligent vehicle systems will use wireless communication to connect a car and its passengers. It is therefore important to understand the in-cabin propagation characteristics of an automobile. This paper investigates the wireless channel native to these cabin enclosures. We present detailed, polarization dependent field measurements over a plane of interest in the cabin, and show that a simple analytical model gives reasonable agreement with our measurements. [ABSTRACT FROM PUBLISHER]

This paper describes an extensive propagation channel measurement campaign in a warehouse environment for line-of-sight (LOS) and nonline-of-sight (NLOS) scenarios. The measurement setup employs a vector network analyzer operating in the 2–8-GHz frequency band combined with an $8 \times 8$ virtual multiple-input multiple-output (MIMO) antenna array. We develop a comprehensive statistical propagation channel model based on high-resolution extraction of multipath components and subsequent spatiotemporal clustering analysis. The intracluster direction of departure (DoD), direction of arrival (DoA), and the time of arrival (ToA) are independent, both for the LOS and NLOS scenarios. The intracluster DoD and DoA can be approximated by the Laplace distribution, and the intracluster ToA can be approximated by an exponential mixture distribution. The intercluster analysis, however, shows a dependency between the cluster DoD, DoA, and ToA. To capture this dependency, we separately model the clusters caused by single and multiple bounce scattering along the aisles in the warehouse. The intercluster DoD distribution follows a Laplace distribution, while the cluster DoA conditioned on the DoD is approximated by a Gaussian mixture distribution. The model was validated using the capacity and delay-spread values. [ABSTRACT FROM AUTHOR]

This paper presents the results of the first propagation measurement campaign conducted in the 2.4 GHz industrial, scientific and medical (ISM) band for low antenna heights in a North American boreal forest. The $2 \times 1$ multiple-input, single output measurements capture propagation conditions for wireless peer-to-peer or sensor networks in the boreal environment. Unlike many other forests, it is shown that ground reflections strongly influence large scale propagation for the low antenna boreal case. Results also indicate that scattering is severe but that both frequency diversity and multiple antenna techniques will be effective for mitigating and/or exploiting the fading caused by this scattering. [ABSTRACT FROM AUTHOR]

The statistic models for evaluating the fading term caused by the incoherent scatter in clear and rainy environments are derived, which are critical for establishing the multiple-input multiple-output (MIMO) channel model at Ka band. The channel model of Ka-band single-polarization MIMO satellite-earth link is established, which comprehensively takes into account the propagation and scattering effects induced by those environments. Based on the channel model, the bit error rate (BER) performances in clear and rainy environments are investigated taking an assumed 2\,\times\,2 satellite-earth link at 30 GHz in circular polarization as an example. During the investigation, the M-ary Phase Shift Keying (M-PSK) modulation modes with different M and the space-time codes of Space-Time Block Code (STBC), Space-Time Trellis Code (STTC) and Vertical Bell Laboratories Layered Space-Time (VBLAST) are considered. It is also discussed that the BER varies with propagation environment parameters, equivalent isotropically radiated power (EIRP), ground receiving antenna gain and elevation angle. The channel model given in this paper is also valid for the single-polarization MIMO satellite-earth link at other frequencies above 10 GHz. [ABSTRACT FROM PUBLISHER]

The physical motivation and interpretation of the stochastic propagation channel model of Saleh and Valenzuela are discussed in detail. This motivation mainly relies on assumptions on the stochastic properties of the positions of transmitter, receiver and scatterers in the propagation environment, and on the frequency range that is covered by the model. Some of these assumptions break down when the application of the model is extended from wideband to ultra-wideband propagation channels. Another important difference between these application contexts is the spatial scale over which the stochastic properties of the channel fluctuate when the transmitter or receiver is moved. This is further illustrated by analyzing the average power delay profile and some other channel properties for different levels of ensemble averaging, and discussing the relation between the ensemble averaging levels and the spatial variation scales. The notion of the averaging levels is essential for correct interpretation of the model, and hence for appropriate channel characterization and system design. [ABSTRACT FROM PUBLISHER]

The objective of this presentation is to illustrate the accuracy of the Schelkunoff formulation over the Sommerfeld solution for a vertical electric dipole radiating over an imperfect ground. In an earlier paper, the alternate form of the Sommerfeld Green's function developed by Schelkunoff was presented (Schelkunoff, 1943 and Dyab, 2013). Here we demonstrate the application of this new methodology for two classes of problems. First, the problem of predicting the propagation path loss in a wireless communication environment is illustrated. The second application problem described in this paper deals with the verification of experimental data related to propagation over an Aluminum sheet at THz frequencies. It is seen that the main contribution of the reflected field is due to a specular image point as expected for a metal and the presence of surface waves in the total reflected field is absent, even though the permittivity of the metal is negative at these frequencies. Both theoretical predictions and experimental data demonstrate that there is little contribution to the reflected field due to a surface wave. Also, a clear definition is made to characterize surface waves as there is confusion as to what a surface wave really is. [ABSTRACT FROM PUBLISHER]

The Rician K-factor of the vehicle-to-vehicle (V2V) wireless propagation channel is estimated using a moment-based method on the envelope of measured pulse data. The measurements were carried out under vehicle-to-vehicle wireless communication channel condition with car rooftop antenna heights at one end of the link and very low antenna height at the other end. Data captured from typical urban, suburban and rural areas are analyzed and the K-factor probability density function is generated for each scenario to give an insight into the V2V channel behavior. For all three areas, the majority of K values are found to be within the range of -10 to +10 dB. The K-factor distributions are close to normal with mean values of 1.8, 2.6 and 3 dB respectively for urban, suburban and rural area. [ABSTRACT FROM PUBLISHER]

This contribution presents an analytical expression to predict the spatial correlation of the rain attenuation A impairing two Earth-space radio links in a site diversity configuration (\rhoA) as a function of the spatial correlation of the rain precipitation affecting the area (\rhoR), of the distance between the two stations d and of the electrical and geometrical characteristics of the links. Well-established properties of the rain field (i.e., quasi-ergodicity and spatial stationarity) are exploited in the derivation of the proposed analytical expression, whose accuracy is evaluated by means of an extensive set of rain field data collected by the NIMROD weather radar network in the UK. Results indicate a satisfactory prediction performance in the 10–50 GHz frequency range, with negligible dependence on the site separation distance d and on the electrical and geometrical characteristics of the system. [ABSTRACT FROM AUTHOR]

A model parameterization and validation is proposed for specular-diffuse clustered channel models. The double-directional model parameters, based on an experimental measurement campaign, are presented. The specular-diffuse model is validated with regard to the following validation metrics: mutual information, singular values, Demmel condition number and ellipticity. A good agreement is observed when comparing the model with experimental measurements. Finally, the influence of the diffuse multipath component on the performance of the model validation is evaluated. [ABSTRACT FROM PUBLISHER]

The effects of carrier frequency, antenna height and season on a broadband wireless access (BWA) system deployed in a rural area at 825 MHz and 3535 MHz are studied in this paper. With the aid of digital terrain information, both large scale and small scale fading effects present in the rural channel are discussed. Our investigation found that the frequency dependence of a wireless channel varies strongly with the environment. Also, the effects of the antenna height in rural areas of irregular terrains vary with the available clearance above the clutters in the regions. This paper uses extensive measurement campaigns to quantify these effects in winter and spring using a BWA system (IEEE 802.16e) deployed in Hetzwege/Abbendorf, Germany. In the study of small scale fading, the variations of the fading distributions of the wireless channel due to season changes are derived and the corresponding multipath propagations are discussed in this paper. [ABSTRACT FROM PUBLISHER]

In ultra-wideband (UWB) wireless propagation channels, each multipath component (MPC) can exhibit delay dispersion or, equivalently, frequency dependence; even more, this dispersion can be different for different MPCs. While this effect is understood to have important implications for UWB system design, extraction of the frequency-dependence parameters from measurements has been lacking. This paper will provide both the theoretical tools for the parameter extraction, and provide experimental results of such parameters in UWB indoor channels. We first develop a method that extracts a single MPC. Based on the image principle, the method identifies locations and intensity of radio sources including both original and image sources (corresponding to MPCs) by a distributed antenna array. We show that the method provides spatial resolution better than 0.5 m and is robust against possible measurement errors. Having applied the method to the measured channels in indoor line-of-sight scenarios, we track the detected image sources over (partially overlapping) frequency subbands to obtain frequency dependent properties of their intensity and location. The variation of the source intensity over the frequency was found to be significant. Furthermore, the locations of the image sources can vary as the frequency changes. Comparison of the results with models that do not describe varying per-path frequency dependence revealed noticeable difference in the shape of the CIRs, and as a result, in the delay spread and the number of significant delay bins for Rake reception. [ABSTRACT FROM PUBLISHER]

Although acoustic waves are the most versatile and widely used physical layer technology for underwater wireless communication networks (UWCNs), they are adversely affected by ambient noise, multipath propagation, and fading. The large propagation delays, low bandwidth, and high bit error rates of the underwater acoustic channel hinder communication as well. These operational limits call for complementary technologies or communication alternatives when the acoustic channel is severely degraded. Magnetic induction (MI) is a promising technique for UWCNs that is not affected by large propagation delays, multipath propagation, and fading. In this paper, the MI communication channel has been modeled. Its propagation characteristics have been compared to the electromagnetic and acoustic communication systems through theoretical analysis and numerical evaluations. The results prove the feasibility of MI communication in underwater environments. The MI waveguide technique is developed to reduce path loss. The communication range between source and destination is considerably extended to hundreds of meters in fresh water due to its superior bit error rate performance. [ABSTRACT FROM PUBLISHER]

The wireless harness is a new emerging short-range communication to replace wire harness implemented in devices with wireless communications between internal components. In such an in-device wireless harness, the communication distance is up to a couple of meters at most. Through the challenge to apply this wireless communication technology to information and communication technology (ICT) equipment, we found that the radio channel inside the ICT equipment deeply depends on its internal structure more than we expected. In order to understand the radio propagation characteristics inside such equipment, we propose a new modeling technique with using a frequency- dependent path loss exponent expressing the near- and far-field propagation, which enables us to successfully extract attenuation factors for the frequency and the propagation distance from the measured data. The results shows the path loss characteristics can be divided into three regions; line-of-sight (LOS), non-line-of-sight (NLOS), and a transition range. The transition range, which appears between the LOS and the NLOS, is caused by a blocking due to the densely-packaged internal components. These findings and equations can be criteria to design a wireless harness communication link. [ABSTRACT FROM AUTHOR]

This paper reports the modeling of foliage attenuation for a broadband wireless access system deployed over mixed terrains in rural areas at 3.5 GHz. The foliage is composed of leaves and leafstalks, and are the dominant scatterers along the transmission paths. The foliage attenuation is determined using the Torrico-Lang model combined with digital topography information. In this model, leaves are modeled as thin lossy circular dielectric discs whereas leafstalks (petioles) are modeled as thin lossy dielectric cylinders. Three measurement campaigns were performed using the mobile WiMAX system (IEEE 802.16 e) deployed in Hetzwege/Abbendorf during winter, spring and mid-summer. Using the winter data as a baseline, the foliage loss due to different degrees of foliation in spring and in winter is studied. The derived foliage loss is then verified and compared with an empirical exponential decay model. [ABSTRACT FROM PUBLISHER]

"Geometric modeling" idealizes the spatial geometric relationships among the transmitter, the scatterers, and the receiver in a wireless propagation channel—to produce closed-form formulas of various channel-fading metrics (e.g., the distribution of the azimuth angle-of-arrival of the arriving multipaths). Scattered in the open literature are numerous such "geometric models," each advancing its own closed-form formula of a fading metric, each based on a different idealization of the spatial geometry of the scatterers. Lacking in the open literature is a comprehensive and critical comparison among all such single-cluster geometric-model-based formulas of the arriving multipaths' azimuth direction-of-arrival distribution. This paper fills this literature gap. The comparison here uses all empirical data legibly available in the open literature for landmobile wireless radiowave propagation. No one geometric model is best by all criteria and for all environments. However, a safe choice is the model with a Gaussian density of scatterers centered at the transmitter. Despite this model's simplicity of having only one degree of freedom, it is always either the best fitting model or offers an LSE within one third of an order-of-magnitude as the best fitting model for all empirical dataset of all environments. [ABSTRACT FROM AUTHOR]

We have characterized the effect of human presence on path gain and time dispersion over ultrawideband (UWB) channels within the passenger cabin of a typical midsize airliner. We measured a few hundred channel frequency responses over the range 3.1-6.1 GHz between various locations within a Boeing 737-200 aircraft, with and without volunteers occupying the passenger seats. The links were deployed in a point-to-multipoint configuration with the transmitting antenna along the centre-line of the forward part of the cabin at either the ceiling or headrest level and the receiving antenna at the headrest or armrest level at selected locations throughout the rest of the cabin. As the density of occupancy increased from empty to full, path gain dropped by no more than a few dB on the ceiling-to-headrest paths but dropped by up to 10 dB on the ceiling-to-armrest and headrest-to-armrest paths. The gain reduction reached its maximum at the mid-point of the cabin and decreased thereafter. In all cases, increasing the density of occupancy caused the distance dependence of the rms delay spread to decrease greatly, the decay rate of the scattered components in the power delay profile (PDP) to almost double and the number of significant paths to drop by almost half. The results suggest that human presence substantially affects both path gain and time dispersion within the aircraft and should therefore be considered when assessing the performance of in-cabin wireless systems. [ABSTRACT FROM AUTHOR]

We study wireless communication via the free modes in a uniform tunnel with non-circular cross section. The dominant modes propagating in such tunnel are considered as perturbed versions of corresponding modes in the well studied circular tunnels. Of particular practical interest are tunnels whose cross section comprise an incomplete circle with flattened base. It is shown that in these tunnels, a vertically polarized mode is more attenuated than its horizontally polarized counterpart.We also investigate the approximation of a non-circular tunnel with an equivalent rectangular tunnel regarding the attenuation of the dominant modes. Comparison is made with experimental attenuation measurements available in the literature. [ABSTRACT FROM AUTHOR]

An experimental investigation to characterize the transient and spectral behavior of the ultrawideband (UWB) on-body radio propagation channel for body-centric wireless communications is presented. The measurements were performed considering over thirty on-body links in the front of human body in the anechoic chamber, and in indoor environment. Two different pairs of planar antennas have been used, namely, CPW-fed planar inverted cone antennas (PICA), and miniaturized CPW-fed tapered slot antennas (TSA). A path loss model is extracted from measured data, and a statistical study is performed on the time delay parameters. The goodness of different statistical models in fitting the root mean square (RMS) delay has been evaluated. Results demonstrate that the TSA, due to its more directive radiation behavior is less affected from the reflections from body parts and surrounding environment. The antenna shows significant size reduction and improved time delay behavior, and hence is an ideal candidate for UWB body area networks (BAN). [ABSTRACT FROM AUTHOR]

A fundamental step in ultrawideband (UWB) communication system design involves the characterization of the indoor propagation channel. In this paper, we show that the UWB propagation channel parameters can be accurately predicted by employing ray tracing (RT) simulation carried out at various frequencies over the signal bandwidth. It is important to note that the determination of the rays reaching a given location is made only once, as the RT algorithm is independent of frequency. A parallel ray approximation (PRA) is used to significantly improve the computational efficiency of the RT based method. Moreover the accuracy of the approximation is verified through a measurement campaign. [ABSTRACT FROM AUTHOR]

A wideband directional measurement campaign was managed inside an arched highway tunnel to analyze the radio propagation channel inside such tunnel for future cellular systems in terms of coverage, delay spread and dominant scatterers. Measurements were performed in 3 rounds with different transmitter positions. Using a wideband channel sounder equipped with a cylindrical dual polarized array at the receiver, the spatio-temporal characteristics of the received propagation paths could be estimated by means of a super-resolution estimation algorithm. The extracted paths using this super-resolution algorithm constitute 88% of the total received power. It was also observed that the line-of-sight component (53%) plus single-bounce scattering (26%) comprise up to 79% of the total received power. In other words, more than 90% (i.e. 79% in 88%) of the extracted paths consists of the line-of-sight component and single-bounce scatterings. The strong contribution from single-bounce scattering paths causes the path gain exponent along the tunnel to be larger than -2 which is the value for free space. This validates that there is wave guiding effect in the tunnel and coverage is extended relative to open space. The rms delay spreads are generally less than 20 ns and increase when influenced by scattering objects such as jetfans. The dominant scatterers are identified and classified into 6 classes based on the structure of the tunnel and existing objects such as ground, wall, light-frame, ceiling, jetfan and cleaner-parking. It was observed that scattering from ground was dominant among all classified scatterers in all scenarios. [ABSTRACT FROM AUTHOR]

An experimental study is described on the natural propagation of UHF band radio waves in straight subterranean galleries. An extensive measurement project took place in five underground localities and, based on the experimental data, an empirical model of radio wave transmission was derived. The model was calibrated according to the measurement data and compared with the theoretical waveguide approach to propagation prediction. The presented results can be used for the practical planning of wireless communications in speleology applications and as an experimental basis for further theoretical works. [ABSTRACT FROM AUTHOR]

The results of signal strength measurements and ray tracing model calculations of indoor propagation at 900 and 1800 MHz are presented. Corridors are being illuminated by ceiling mounted 2 dB gain omni antennas. The objectives of these experiments are to study behavior of the received signal strength at 900 and 1800 MHz in comparison of cell coverage, signal attenuation and variation through the line of sight (LOS) and non line of sight (NLOS) orientation of halls. It is shown that large fluctuations occur between average signal levels in LOS and NLOS case of propagation. It is also obtained that ray tracing model neglecting diffraction effects work better for LOS then NLOS, and requires detailed database information for better prediction. [ABSTRACT FROM AUTHOR]

The design of a novel ultrawideband printed-circuit antenna is presented. By using a stepped-patch in combination with multiple resonating elements, a bandwidth of more than 150% is obtained. The performance is demonstrated through measurements and calculations with a commercially available field solver. A phase center analysis shows very small variations over the entire available bandwidth. [ABSTRACT FROM AUTHOR]

Radiocoverage measurements in urban environments often unveil unexpected power distribution patterns. Architectural features seem to be the cause of this behavior, as demonstrated in this paper. We demonstrate that the elements of a typical building facade, such as windows, exterior doors, balconies' and railings, should be considered as significant ‘sources’ of EM radiation in several current wireless communication systems. We propose a method for modeling the influence of those scatterers in EM wave propagation. In our model, the major structural elements are represented by two sets of orthogonally arranged wedges. The uniform geometrical theory of diffraction is employed to calculate the scattering field. The simulation results show that such ‘urban’ scatterers may create a dominant propagation mode in an urban canyon. Our predictions are additionally verified by experimental measurements, performed at two different sites. Finally, the influence of roadside foliage is investigated and conclusions are drawn on the resultant field. [ABSTRACT FROM AUTHOR]

We investigate several sampling strategies in performing model-based parameter estimation based on the rational function model. They are: i) uniform-like sampling; ii) random sampling; and iii) sampling based on the Fisher information theory. The sampling strategies are implemented for the calculation of the input impedance of an antenna over a broad frequency range. The model parameters of the rational functions are found by the Cauchy method. The results are evaluated against the optimal sampling solution obtained by a genetic algorithm search. [ABSTRACT FROM AUTHOR]

Multiantenna systems. such as devices for multiple-input-multiple-output (MIMO) communication can theoretically use array superdirectivity to optimally exploit the propagation channel. In traditional analyses of MIMO systems, such superdirectivity is not observed due to the commonly applied constraint that limits the excitation current magnitudes. However, when an electromagnetically appropriate constraint on the power radiated by the array is applied, the computed capacity can include effects of transmit superdirectivity. A similar result occurs at the receiver for spatially colored noise. This paper formulates the MIMO system capacity under these circumstances and provides a framework for computing this capacity when the level of tolerable superdirectivity (as measured by the superdirectivity Q factor) is constrained. Example computations using the framework illustrate the impact that superdirectivity can have on achievable MIMO system performance. [ABSTRACT FROM AUTHOR]

A novel approach of a parametric stochastic radio channel model describes the dispersive nature of the wave propagation in indoor and outdoor environments with regard to delay and incidence angle. Effects of large-scale fluctuations are considered, too. Channel dispersion is mathematically denoted by the delay-angle spread function which results from the coherent superposition of the contributions arising from a certain number of multipath components (MPC). A classification of the propagation scenarios can be achieved by means of their topological properties. Local parameters defining the instantaneous constellation of the impinging MPC as well as global parameters giving a statistical characterization of the propagation environment (PE) are derived and form the elements of the channel model. This paper focuses on two indoor PE characterized by a line-of-sight (LOS) and a nonline-of-sight (NLOS) connection between the transmitter and receiver, respectively. Measurements in the 24 GHz range (ISM band) are presented to demonstrate the physical properties of the propagation process in both PE and to determine their global parameters. LOS scenarios show "discrete" MPC arising from specular reflections. In case of a NLOS situation the MPC exhibit a clustering pattern due to building and wall structures which can be statistically described by means of a cluster model, an extension of the previously given modeling approach. [ABSTRACT FROM AUTHOR]

Deals with the use of a time-domain (TD) analysis for the prediction of radio wave propagation for wireless communications in urban environments. Comparison between measured propagation data and predictions given by a polygonal line (PL) simulator; Purpose of the TD analysis; Appraisal of predictions obtained with the PL simulator.

Demonstrates the ability of a statistical multipath propagation model to match capacity statistics and pairwise magnitude and phrase distributions of a multiple-input multiple-output (MIMO) data wireless channel. Comparison between the propagation model and MIMO data; Discussion on the modeling of antenna elements employing multiple polarizations; Facts on the use of joint probability density functions.

Describes a number of three-dimensional direction-of-arrival measurements in a small cell environment at 1845 mega hertz. Growth in demand for mobile and wireless communications; Propagation paths found using the vertical plane launch method; Angle of arrival comparisons; Time response for the received signal radiosity.

Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers. [ABSTRACT FROM PUBLISHER]