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The critical rule to achieve extremely high peaks of data transmission is the availability of a tremendous amount of bandwidth. The super high frequency (SHF) and the millimeter-wave (mmWave) frequency bands are the candidates for the deployment of the 5C cellular system and for satisfying future needs due to their massively available blocks of contiguous raw bandwidth that is capable of supporting additional data traffic for multimedia services. This research paper presents propagation measurements at three frequencies above 6 GHz, which are 14, 18, and 22 GHz frequency bands. The measurements were carried out for both line-of-sight (LOS) and non-line-of-sight (NLOS) communication scenarios in an indoor corridor environment to present frequency- and distance-dependent wireless channel models. Moreover, this study presents, investigates, and compares the performance of two well-known path loss prediction models; the single frequency close-in (CI) free space reference distance model and the single frequency floating intercept (FI) model. The LOS comparison study shows that the CI and FI models provide comparable and accurate estimates that fit the real measured data for the frequency bands selected. Furthermore, the study investigates the behavior of the path loss exponent (PLE) and the FI model parameters as a function of the reception angle of arrival (AoA) in the NLOS scenario. It is observed from this work that the path loss models' parameters exhibit symmetrical behavior around 180° AoA. The FI model provides the same standard deviation values as the CI model in the LOS scenario. In contrast, the FI model offers a notable reduction (up to 2.84 dB) compared to the CI model in the NLOS scenario. Finally, the LOS and NLOS results reveal that the CI and FI models can be trusted as good path loss models for corridor environments and exhibit stable behavior over measured distances and frequencies.

In this paper, a path loss characterization at millimeter-wave (mmWave) frequencies is performed in a typical indoor office environment. Path loss results were derived from propagation channel measurements collected in the 25–40 GHz frequency band, in both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions. The channel measurements were performed using a frequency-domain channel sounder, which integrates an amplified radio over fiber (RoF) link to avoid the high losses at mmWave. The path loss was analyzed in the 26 GHz, 28 GHz, 33 GHz and 38 GHz frequency bands through the close-in free space reference distance (CI) and the floating-intercept (FI) models. These models take into account the distance dependence of the path loss for a single frequency. Nevertheless, to jointly study the distance and frequency dependence of the path loss, multi-frequency models were considered. The parameters of the ABG (A-alpha, B-beta and G-gamma) and the close-in free space reference distance with frequency path loss exponent (CIF) models were derived from the channel measurements in the whole 25–40 GHz band under the minimum mean square error (MMSE) approach. The results show that, in general, there is some relationship between the model parameters and the frequency. Path loss exponent (PLE) values smaller than the theoretical free space propagation were obtained, showing that there are a waveguide effect and a constructive interference of multipath components (MPCs). Since the measurements were obtained in the same environment and with the same configuration and measurement setup, it is possible to establish realistic comparisons between the model parameters and the propagation behavior at the different frequencies considered. The results provided here allow us to have a better knowledge of the propagation at mmWave frequencies and may be of interest to other researchers in the simulation and performance evaluation of future wireless communication systems in indoor hotspot environments. This work has been funded in part by the MCIN/AEI/10.13039/501100011033/ through the I+D+i Project under Grant PID2020-119173RB-C21 and Grant PID2020-119173RB-C22, and by COLCIENCIAS in Colombia.

This paper presents 28 GHz wideband propagation channel characteristics for millimeter wave (mmWave) urban cellular communication systems. The mmWave spectrum is considered as a key-enabling feature of 5G cellular communication systems to provide an enormous capacity increment; however, mmWave channel models are lacking today. The paper compares measurements conducted with a spherical scanning 28 GHz channel sounder system in the urban street-canyon environments of Daejeon, Korea and NYU campus, Manhattan, with ray-tracing simulations made for the same areas. Since such scanning measurements are very costly and time-intensive, only a relatively small number of channel samples can be obtained. The measurements are thus used to quantify the accuracy of a ray-tracer; the ray-tracer is subsequently used to obtain a large number of channel samples to fill gaps in the measurements. A set of mmWave radio propagation parameters is presented based on both the measurement results and ray-tracing, and the corresponding channel models following the 3GPP spatial channel model (SCM) methodology are also described.

In this letter, we present a path loss characterization of the vehicular-to-vehicular (V2V) propagation channel. We have assumed a path loss model suitable for vehicular ad hoc networks (VANETs) simulators. We have investigated the value of the model parameters, categorizing in line-of-sight (LOS) and non-LOS (NLOS) paths. The model parameters have been derived from extensive narrowband channel measurements at 700 MHz and 5.9 GHz. The measurements have been collected in typical expected V2V communications scenarios, i.e., urban, suburban, rural, and highway, for different road traffic densities, speeds, and driven conditions. The results reported here can be used to simulate and design the future vehicular networks.

International audience; Current shipboard monitoring systems use extensive lengths of cables to connect sensors to control units. Replacing wired connections by wireless ones may be an efficient solution to reduce the ship weight and cost. Ships are characterized by a specific metallic environment which can severely decrease the efficiency of wireless networks due to signal attenuation and multipath effects. In this paper, we present a feasibility study of a Wireless Sensor Network (WSN) using ubiquitous technologies on board vessels. A measurement campaign has been conducted on board a ferry to investigate the radio propagation challenges of wireless communications in this particular environment. Path loss models have been obtained for typical shipboard environments. Engineering rules concerning the placement and the number of communication nodes needed to cover the decks and maintain the network connectivity have been determined. Based on these results, an IEEE 802.15.4 compliant WSN has been tested on board the same ferry. Sensor nodes have been placed on the four decks of the ferry and the base station has been placed in the control room located in the bottom deck. Results show an excellent performance with respect to transmission ratio of sensor nodes and a significant connectivity between nodes located in different compartments and decks separated by metallic watertight doors.

This paper compares three candidate large-scale propagation path loss models for use over the entire microwave and millimeter-wave (mmWave) radio spectrum: the alpha-beta-gamma (ABG) model, the close-in (CI) free space reference distance model, and the CI model with a frequency-weighted path loss exponent (CIF). Each of these models have been recently studied for use in standards bodies such as 3GPP, and for use in the design of fifth generation (5G) wireless systems in urban macrocell, urban microcell, and indoor office and shopping mall scenarios. Here we compare the accuracy and sensitivity of these models using measured data from 30 propagation measurement datasets from 2 GHz to 73 GHz over distances ranging from 4 m to 1238 m. A series of sensitivity analyses of the three models show that the physically-based two-parameter CI model and three-parameter CIF model offer computational simplicity, have very similar goodness of fit (i.e., the shadow fading standard deviation), exhibit more stable model parameter behavior across frequencies and distances, and yield smaller prediction error in sensitivity testing across distances and frequencies, when compared to the four-parameter ABG model. Results show the CI model with a 1 m close-in reference distance is suitable for outdoor environments, while the CIF model is more appropriate for indoor modeling. The CI and CIF models are easily implemented in existing 3GPP models by making a very subtle modification -- by replacing a floating non-physically based constant with a frequency-dependent constant that represents free space path loss in the first meter of propagation., Comment: Open access available at: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7434656

We have performed a propagation measurement campaign at the University of Rome Tor Vergata, Rome, Italy. We have sounded the channel by a probing signal at a carrier frequency of 4.78 GHz modulated by a train of pulses having a duration of 0.4 ns shaped by a pseudonoise (PN) sequence. The measurement band falls (3.6-6 GHz) in the frequency range allowed by the FCC ruling for ultrawide-band (UWB) operations. To characterize the channel behavior over the large and the small scale, the transmitter is moved in six different positions on the floor, while the receiver is moved in 625 different locations within each room. The receiver locations are arranged in a square grid of 25/spl times/25 points with 2 cm spacing, i.e., less than half of the minimum wavelength of the transmitted signal. A total of 625/spl times/16 impulse responses are recorded in nonline-of-sight (NLOS) conditions, 625 in line-of-sight (LOS) conditions within the rooms and 11 LOS measurements are made in the corridor at incremental spacing of 1 m. We describe the measurement technique as well as the procedure by which we process the experimental data to extract the amplitude, phase and delay associated to each component of the multipath profiles. We also derive path-loss and shadowing models for the UWB indoor channel in both LOS and NLOS conditions. Finally, we present an accurate analysis of the time dispersion of the UWB channel.