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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]

Physical models describe the radio channel by characterizing the multipath propagation. Also, measurements are frequently employed in the establishment of such models, or for tuning the existing ones. This paper presents a systematic analysis of double-directional radio channel data, obtained by combining two single-input multiple-output measurements (forward and reverse), each, containing the channel frequency responses at the locations of a virtual rectangular antenna array. The measurement setup uses a vector network analyzer, which, together with the adopted data processing, represents an affordable, but very consistent, alternative to more sophisticated equipment, given that, a physical analysis of the identified channel contributions provided sensible results. The study comprised three main steps: 1) the characterization of each single-directional channel by employing a high-resolution algorithm to obtain the parameters of a chosen number of multipath components (MPCs); 2) the classification of the obtained MPCs in a twofold way, first, by grouping MPCs using clustering tools, and, second, by classifying these clusters according to their type of interaction with the propagation scenario; and 3) the extraction of typical values for the number of clusters, the number of MPCs per cluster, rules for power decay, and statistical distributions for inter and intracluster delays and azimuths. [ABSTRACT FROM AUTHOR]

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]

Radio propagation in confined spaces is consequent upon reflections by the boundaries. In such cases, the relative position and polarization of antennas becomes important. This paper investigates the effect of antenna position and polarization on ultra-wideband radio propagation in underground mines and tunnels. Analysis is based on channel measurements, over 2.4 to 4 GHz frequency band, in three tunnels of varying cross-sectional dimensions and lengths. Effects of mounting antennas on ceiling versus walls and horizontal versus vertical polarization are compared in terms of path loss and time dispersion. Results show that average path loss is more sensitive to antenna position and polarization, than is time dispersion. The effect of polarization is found to be dependent upon antenna position. Horizontal polarization results in less average path loss when the antennas are mounted close to the ceiling, whereas vertical polarization results in less average loss when mounted close to a side wall. It is demonstrated that carefully considering antenna position and polarization can result in more efficient and cost-effective deployment of UWB systems in underground environments. [ABSTRACT FROM PUBLISHER]

This paper presents the large scale parameters of wideband multipath channels based on extensive measurement campaigns in various indoor environments. The measurements were conducted with a wideband multiple-input multiple-output (MIMO) channel sounder having a bandwidth of 400 MHz at 11 GHz which is a challenging frequency for future mobile systems. In particular, polarization characteristics of path-loss, shadowing, cross-polarization power ratio (XPR), delay spread and coherence bandwidth are characterized. The measurement results show that the path-loss exponents range between 2.0 and 3.0 for none-line-of-sight (NLoS), 0.36 and 1.5 for LoS, respectively. Vertically and horizontally polarized transmissions have almost same path-gain, but in some corridor-room NLoS environments, the path-loss for HH is significantly large. In most cases, the RMS delay spreads are less than 20 and 50 ns for NLoS and LoS, respectively, and the average coherence bandwidth is less than 30 MHz. The Rician K-factors range between 2 and 3 dB for cross-polarization, and in large Hall environments, those for co-polarization are greater than 6.0 dB with 10% probability. Finally, some dominant propagation mechanism and site-specific behaviors are illustrated using the double-directional measurement results. [ABSTRACT FROM AUTHOR]

A comparison of the presence of cylindrical against rectangular obstacles in radio wave multiple-diffraction analysis is performed both theoretically—through hybrid formulations based on the uniform theory of diffraction (UTD) and physical optics (PO)—and experimentally—through measurements performed at 60 GHz. The results can be applied to the analysis of multiple diffraction in the mm-wave band when propagation over periodic obstacle patterns—either rounded or flat—has to be considered. [ABSTRACT FROM AUTHOR]

A hybrid uniform theory of diffraction-physical optics (UTD-PO) formulation for the analysis of multiple-diffraction of spherical waves by a series of rectangular plateaux is compared with measurements performed at 62 GHz. The comparison shows a solid agreement between predicted and measured results. Therefore, since the array of plateaux under investigation can be considered as a scaled-model of an urban environment, the results support the validity of the proposed UTD-PO formulation in the analysis of urban radiowave propagation. [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]

Linear-/circular-polarization designs of the dual-/wide-band cylindrical dielectric resonator antennas (DRAs) are presented. The HEM111 and HEM113 modes of the cylindrical DRA are utilized to design the dual-mode cylindrical DRA. A wideband antenna can be obtained by merging the two resonant modes. To facilitate the designs, new engineering formulas that determine the dimensions of the dual-mode cylindrical DRA are found for the first time. They are obtained by using the covariance matrix adaptation evolutionary strategy (CMA-ES). Design examples for the dual-/wide-band cylindrical DRAs are given for both the linearly and circularly polarized cases. Ansoft HFSS was used to simulate the DRAs and the simulations were verified with our measurements. Good agreement between the measured and simulated results is observed. [ABSTRACT FROM PUBLISHER]

Using a similar approach to that applied in acoustics and in microwave reverberation chambers, a theory of wideband propagation in a closed environment is discussed. Here, a room environment is viewed as a lossy cavity, characterized by diffuse scattering from walls and internal obstacles. For experimental results, measurements from 3 to 8 GHz were performed in a 24 passenger section of an aircraft cabin. This UWB system has the transmitter at ceiling height and the receivers at armrest and headrest positions. The measurements were performed for the cabin being unoccupied and fully occupied. In the theoretical model, the closed room environment is characterized by the reverberation time and volume, and these parameters allow derivation of the the remaining parameters such as path loss and average passenger absorption. The RMS delay spread and mean excess delay are also studied. For the mean power the agreement between the theory and measurements is good to within 1–2 dB, indicating the excellent accuracy of the method, which extends to estimating body absorption in real world environments. The total absorption from the seated passengers is dominated by the few who are near the transmitter. In general, this absorbed power is relatively small, so the effect of passengers is marginal for this configuration of a cabin communication system. [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 proposes the deployment of frequency selective surfaces (FSS) in indoor wireless environments and investigates their effect on radio wave propagation. FSS can be deployed to selectively confine radio propagation in indoor areas, by artificially increasing the radio transmission loss naturally caused by building walls. FSS can also be used to channel radio signals into other areas of interest. Simulations and measurements have been carried out in order to verify the frequency selectivity of the FSS. Practical considerations regarding the deployment of FSS on building walls and the separation distance between the FSS and the supporting wall have been also investigated. Finally, a controlled, small-scale indoor environment has been constructed and measured in an anechoic chamber in order to practically verify this approach through the usage of ray tracing techniques. [ABSTRACT FROM AUTHOR]