Terms Of Path Loss Research Articles

Wearable Dual-Layer Planar Magnetoinductive Waveguide for Wireless Body Area Networks

We have previously reported wearable magnetoinductive waveguides (MIW) for wireless body area networks (WBANs) that significantly outperform the state-of-the-art in terms of path loss, data rate, interference, security, and more. MIWs placed in a planar way upon the human body are most promising but suffer from a large deterioration in performance under mechanical failures and clothing transitions (e.g., from 10.34 dB to 27.31 dB minimum loss and from 20% to 2.32% fractional bandwidth). In this work, we overcome both limitations via a novel dual-layer planar MIW design that utilizes two layers of resonant loops stacked upon each other. Concurrently, this design maintains all benefits of MIW-based WBANs and improves the link budget by >5 dB vs. our previous single-layer MIWs and by >60-70dB vs. state-of-the-art WBANs. We herewith report a theoretical model of dual-layer MIWs that relies on the dispersion relation and validate it both numerically and experimentally. We also discuss the improvements vs. our previously reported MIW designs and address design considerations, including electromagnetic safety. This work cements MIWs as a future technology to be used in low-loss WBANs for full body applications.

Performance analysis of mmWave radio propagations in an indoor environment for 5G networks

Existing wireless communications in the sub-6 GHz bands are facing challenges from the growing demand for higher data rates and better quality of services. To satisfy these demands, the fifth generation (5G) mobile network would consider unused spectrum in the millimeter wave (mmWave) spectrum (30–300 GHz). The shortage of bandwidth in the sub-6 GHz band is solved using mmWave technology. Furthermore, mmWave provides significantly higher throughput, data rate, and capacity. Despite the fact that a huge bandwidth is employed, mmWave technology suffers from diffuse scattering from rough materials, path loss, reflection loss, atmospheric attenuation, building penetration loss, and shadowing which leads to a decrease in the transmitted signal power. Therefore, a reliable and accurate channel model is important in the mmWave bands, particularly for the indoor environment. Moreover, by using technologies like beam-forming and others coupled with mmWave, the listed impairments are minimized. In this work, we analyze the performance of different path loss models (CI, free space, and two rays) at 38, 60, and 73 GHz carrier frequencies in terms of path loss in terms of separation distance between transmitter and receiver. Additionally, we have evaluated the performance of the path loss with respect to the break point distance to enhance the received signal power and throughput. We have also done analysis of the directional power delay profile with received signal power, path loss and path loss exponent (PLE) at 38 GHz and 73 GHz mmWave bands for both LOS and NLOS by using uniform linear array (ULA) 2 × 2 and 64 × 16 antenna configurations using the channel model simulator (NYUSIM). The simulation results show the performance of different path loss models in the mmWave and sub 6 GHz bands. Path loss in the close-in (CI) model at mmWave bands is larger than that of free space and two ray path loss models, because it considers all shadowing and reflection effects between transmitter and receiver.

Bridging Nano and Body Area Networks: A Full Architecture for Cardiovascular Health Applications

Cardiovascular events occurring in the bloodstream are responsible for about 40% of human deaths in developed countries. Motivated by this fact, we present a new global network architecture for a system for the diagnosis and treatment of cardiovascular events, focusing on problems related to pulmonary artery occlusion, i.e., situations of artery blockage by a blood clot. The proposed system is based on bio-sensors for detection of artery blockage and bio-actuators for releasing appropriate medicines, both types of devices being implanted in pulmonary arteries. The system can be used by a person leading an active life and provides bidirectional communication with medical personnel via nano-nodes circulating in the bloodstream constituting an in-body area network. We derive an analytical model for calculating the required number of nano-nodes to detect artery blockage and the probability of activating a bio-actuator. We also analyze the performance of the body area component of the system in terms of path loss and of wireless links budget. Results show that the system can diagnose a blocked artery in about 3 h and that after another 3-h medicines can be released in the exact spot of the artery occlusion, while with current medical practices the average time for diagnosis varies between 5 and 9 days.

Single Channel Equivalent Point Processes of Poisson Networks With Multiple Channel Laws

We present the construction and characterization of novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">single channel equivalent</i> representations of a Poisson Point Process (PPP) whose points follow multiple channel laws with respect to the origin. Two variants are presented. The first, called the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Type 1</i> Equivalent Process (EPP), allows for IID fading while maintaining equivalence in terms of path loss and fading with respect to a single channel law. The second, called the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Type 2 EPP</i> , also maintains equivalence with respect to a single channel law, but requires the fading distribution to be dependent on the underlying point process. The Type 1 EPP only exists in certain settings, while the Type 2 EPP always exists.

Channel Characterization of Magnetic Human Body Communication.

The objective of this paper is to model and experimentally validate the path loss benefits of magnetic human body communication (mHBC) using small form-factor-accurate coils operating under realistic conditions. A radiating near-field coupling model and numerical simulations are presented to show that the magnetic-dominant near-field coupling between resonant coils offers low path loss across the body and exhibits extra robustness to antenna misalignment compared to far-field RF schemes. To overcome the pitfalls in conventional vector-network-analyzer-based measurement configurations, we propose a standardized setup applied to broadband channel loss measurement with portable instruments. Two types of PCB coils for mHBC communication, designed for large devices such as smartphones and small devices such as earbuds, respectively, are built and measured. The mHBC link for the ear-to-ear non-line-of-sight (NLOS) path measures up to -23.1 dB and -31.2 dB with large and small coils, respectively, which is 50 dB more efficient than the conventional Bluetooth channels utilizing antennas of similar sizes. Ear-to-pocket and pocket-to-pocket channels also show at least 16 dB higher transmission than the Bluetooth channel. In terms of path loss, the mHBC approach offers compelling performance for short-range applications over the body region. For coils with dimensions of several centimeters, working between 100 MHz and 200 MHz minimizes the channel loss while keeping the bandwidth above 1 MHz. The extremely high efficiency of the proposed mHBC channel provides a solution to the energy problem for miniaturized wearables, potentially leading to new wearable device designs.

Buffer occupancy and link state opportunistic routing for wireless mesh networks

Providing a high level of Quality of Service is essential for future wireless networks. This article presents a new multihop wireless routing protocol that opportunistically takes profit from variations of radio conditions in terms of path loss, shadowing and multipath fading to maximize the system capacity. However, guaranteeing high system capacity should not evade the packet delay minimization objective. Consequently, the best path should not only be considered as the path with best throughput but a combination of a good link throughput and, in addition, low router buffer occupancy load. Taking into account the available router buffer occupancy in its path selection, our proposal uses queuing theory information in order to also provide an efficient load balancing solution that adequately distributes the traffic load in the whole network. Exploiting this information, our solution dynamically adapts the selected path across time avoiding overexploited efficient links as well as low throughput link usage. This adaptation is performed considering each link state and the amount of channel information available. This improves the throughput and delay with only small marginal overhead cost. Our proposal applies to all wireless multihop networks, with increased benefit for extending cell coverage. We demonstrate through our simulation study that our solution raises the system capacity by more than 50% in several scenarii as well as reduces packet delays compared to state-of-the-art protocols such as Ad-hoc On-demand Distance Vector, Optimized Link State Routing and Link State Opportunistic Routing.

Multi‐UAV and SAR collaboration model for disaster management in B5G networks

Ensuring communication infrastructures always alive during disaster mitigation and recovery is of paramount importance. In this case, Unmanned Aerial vehicle (UAV) will be the ideal substitute for the malfunctioning ground base station due to disaster. Henceforth, we suggest a multi‐UAV and Search and Rescue (SAR) collaboration model in this letter. To improve its connectivity, we propose an optimal SAR elevation angle for the multi‐UAV and SARs to administer larger disaster areas effectively and efficiently. We evaluate the performance of the proposed model in terms of path loss, throughput, and coverage probability. The results demonstrate that the proposed model achieves a significant enhancement in serving the SARs.

VIVID: In Vivo End-to-End Molecular Communication Model for COVID-19.

As an alternative to ongoing efforts for vaccine development, scientists are exploring novel approaches to provide innovative therapeutics, such as nanoparticle- and stem cell-based treatments. Thus, understanding the transmission and propagation dynamics of coronavirus inside the respiratory system has attracted researchers’ attention. In this work, we model the transmission and propagation of coronavirus inside the respiratory tract, starting from the nasal area to alveoli using molecular communication theory. We performed experiments using COMSOL, a finite-element multiphysics simulation software, and Python-based simulations to analyze the end-to-end communication model in terms of path loss, delay, and gain. The analytical results show the correlation between the channel characteristics and pathophysiological properties of coronavirus. For the initial 50% of the maximum production rate of virus particles, the path loss increases more than 16 times than the remaining 50%. The delayed response of the immune system and increase in the absorption of virus particles inside the respiratory tract delay the arrival of virus particles at the alveoli. Furthermore, the results reveal that the virus load is more in case of asthmatic patients as compared to the normal subjects.

Performance analysis of millimeter wave 5G networks for outdoor environment: propagation perspectives

&lt;span&gt;To cope with the massive growth in global mobile data traffic for 2020 and beyond, the Fifth Generation (5G) system is required to be developed as the current 4G system is expected to fall short behind the provision of such growth. 5G systems is anticipated to use millimeter wave (mm-wave) frequency bands (20 to 90) GHz, due to the availability of wide chunk of unexploited bandwidth. This is revolutionary step to use these bands because of their very different propagation conditions, atmospheric absorption and hardware constraints. However, such challenges could be compensated by means of beamforming/beamsteering and larger antenna array. In this paper, a comparative study aided with ray-tracing simulation has been performed to assess the feasibility of mm-wave in 5G system. Propagation characteristics of the 28GHz and 73 GHz bands have been studied and compared in a street canyon outdoor environment to simulate 5G outdoor mobile access. Simulation results were shown along with their comparison for both of the aforementioned frequencies. The results of propagation comparison have been reported in terms of path loss, k-factor, delay spread and received power for both 28 and 73 GHz bands.&lt;/span&gt;

The TeraNova platform: An integrated testbed for ultra-broadband wireless communications at true Terahertz frequencies

Terahertz (THz)-band (0.1 THz to 10 THz) communication is envisioned as a key technology to meet the demand for faster, more ubiquitous wireless communication networks. For many years, the lack of compact, fast and efficient ways to generate, modulate, detect and demodulate THz-band signals has limited the feasibility of such communication systems. Recently, major progress within different device technologies is finally closing the so-called THz gap. For the time being, communication testbeds have been developed at sub-THz frequencies, i.e., at or near the boundary with millimeter-wave communication systems. Nonetheless, higher carrier frequencies and their associated bandwidth are needed to meet the demand for much higher data rates. In this paper, the TeraNova platform, i.e., the first integrated testbed for ultra-broadband wireless communications at true THz-band frequencies, is presented. The system consists of a transmitter and a receiver based on Schottky-diode frequency multiplying and mixing chains able to up & down-convert an information-bearing intermediate frequency (IF) signal up to 40 GHz-wide between 1 and 1.05 THz, i.e., the first absorption-defined transmission window above 1 THz. Guided by the experimental characterization of the THz channel in terms of path-loss and noise, tailored framing, time synchronization, channel estimation and single- and multi-carrier modulation techniques are implemented in software and realized by a state-of-the-art arbitrary waveform generator and a digital storage oscilloscope at the transmitter and the receiver, respectively. Experimental results are presented herein to highlight the opportunities and challenges to unleash the potential of the THz band.

Body-to-Body Channel Characterization and Modeling Inside an Underground Mine

In this article, the use of circularly polarized multiple-input–multiple-output (MIMO) antenna systems is proposed as a new solution for future body-to-body (B2B) applications. Four B2B channels have been characterized inside a mine. The statistical parameters of the B2B channels using co-positioned (CP) and 90° rotated (90R) antennas have been determined. Path loss (PL) exponent values varied between 2.33 and 1.26. The time dispersion parameters and channel capacities are computed for both CP and 90R scenarios. Moreover, channel correlation matrices and the Rician K-factor have been determined and discussed in terms of their effect on capacity and root mean square (rms) delay spread. Overall, the circularly polarized setup exhibits the best performance in terms of PL, rms delay spread, and channel capacity. The nonline-of-sight (NLOS) situation caused a significant drop in channel capacity due to the significant increase in PL, and an increase in the rms delay spread due to the multipath richness. The MIMO-NLOS scenario exhibits the highest throughput gain of 1.752 (at an SNR of 20 dB), due to its low branch correlation. A model of the B2B impulse response has been created based on a statistical–empirical approach to determine the optimal path amplitudes and time of arrival.

Channel Characterization for Intra-Wagon Communication at 60 and 300 GHz Bands

In this paper, the intra-wagon channels at 60 and 300 GHz bands are characterized through measurement-validated ray-tracing (RT) simulations. To begin with, an in-house-developed three-dimensional RT simulator is calibrated and validated by a series of millimeter-wave and Terahertz channel measurements inside a high-speed train wagon. Then, the validated RT simulator is used to conduct extensive simulations with different transmitter (Tx) and receiver deployments. At low frequencies, the channel is strongly influenced by the line of sight (LOS), and therefore, is usually classified into LOS and non-LOS (NLOS) regions. However, the simulation results at 60 and 300 GHz bands show that the first-order reflection also imposes a significant impact on the channel characteristics. This motivates us to further classify the NLOS region into light-NLOS (L-NLOS) and deep-NLOS (D-NLOS) according to the existence of the first-order reflection. Through analyzing the area ratios of LOS, L-NLOS, and D-NLOS regions, we evaluate the Tx deployment strategies and suggest the optimum one. Based on RT simulation results, totally 12 cases (three propagation regions with two Tx deployments at two frequencies) are characterized in terms of path loss, shadow fading, root-mean-square delay spread, Rician $K$ -factor, azimuth/elevation angular spread of arrival/departure, cross-polarization ratio, and their cross correlations. All these parameters are fed into the 3GPP-like quasi-deterministic radio channel generator (QuaDRiGa). The good agreement between QuaDRiGa and RT proves that the 13 tables provided in this paper effectively parameterize the intra-wagon scenario for the standard channel model family. These results provide valuable insights into the system design and evaluation for intra-wagon communications.

Measurement, Simulation, and Characterization of Train-to-Infrastructure Inside-Station Channel at the Terahertz Band

In this paper, we measure, simulate, and characterize the train-to-infrastructure (T2I) inside-station channel at the terahertz (THz) band for the first time. To begin with, a series of channel measurements is performed in a train test center at 304.2 GHz with 8 GHz bandwidth. Rician K-factor and root-mean-square (RMS) delay spread are extracted from the measured power-delay profile. With the aid of an in-house-developed ray-tracing (RT) simulator, the multipath constitution is physically interpreted. This provides the first hand information of how the communicating train itself and the other train on site influence the channel. Using this measurement-validated RT simulator, we extend the measurement campaign to more realistic T2I inside-station channel through extensive simulations with various combinations of transmitter deployments and train conditions. Based on RT results, all cases of the target channel are characterized in terms of path loss, shadow fading, RMS delay spread, Rician K-factor, azimuth/elevation angular spread of arrival/departure, cross-polarization ratio, and their cross correlations. All parameters are fed into and verified by the 3GPP-like quasi-deterministic radio channel generator. This can provide the foundation for future work that aims to add the T2I inside-station scenario into the standard channel model families, and furthermore, provides a baseline for system design and evaluation of THz communications.

Channel Model and Interference Evaluation for a Wireless Train Backbone

Modern trains have become a complicated ensemble of both mechanic and electronic systems. In particular, the so called Train Control and Management System (TCMS) plays a key role in them. TCMS-related applications and services run over a dedicated network called TCN (Train Communications Network) which is wired. Therefore, the opportunity for a wireless TCN is clear, but the challenges and threats are also remarkable. In this article we characterize the radio channel for a very important scenario: the train backbone, which includes the impact on adjacent trains (due to interferences). In order to be exhaustive and to provide useful and accurate models, a measurement campaign on three different real-world scenarios (with trains involved) has been carried out: tunnels, open air and stations. Physical layer results are provided in terms of path-loss, power-delay profile and fading distribution characterization.

A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz⁻2.4 GHz Range.

While there exists a wide variety of radio frequency (RF) technologies amenable for usage in Wireless Body Area Networks (WBANs), which have been studied separately before, it is currently still unclear how their performance compares in true on-body scenarios. In this paper, a single reference on-body scenario—that is, propagation along the arm—is used to experimentally compare six distinct RF technologies (between 420 MHz and 2.4 GHz) in terms of path loss. To further quantify on-body path loss, measurements for five different on-body scenarios are presented as well. To compensate for the effect of often large path losses, two mitigation strategies to (dynamically) improve on-body links are introduced and experimentally verified: beam steering using a phased array, and usage of on-body RF repeaters. The results of this study can serve as a tool for WBAN designers to aid in the selection of the right RF frequency and technology for their application.

Multiple‐input multiple‐output beam‐space for high‐speed wireless communication in underground mine

This study presents a new low-cost multiple-input multiple-output (MIMO) beam-pace technique to increase the overall link capacity of wireless MIMO communications systems in scatter-rich underground mines. This technique is based on generating multiple orthogonal beams for data spatial multiplexing using conformal cylindrical-shape patch arrays. Hence, this study is intended to reveal interests towards the use of conformal MIMO systems for underground mine communications. Two separate 4 × 4 MIMO measurement campaigns are performed and then investigated in a comparative way; the first uses conformal microstrip patch arrays (CMPA), while the second uses conventional planar microstrip patch arrays (PMPA). Based on sweeping-frequency technique (2.35–2.55) GHz, the channel performance is characterised in terms of path loss, fading distribution, capacity and RMS time dispersion parameters. Whether under a line of sight (LOS) or a non-LOS (NLOS) condition, the extracted results confirm the performance priority of CMPA for underground mines communications as they further enhance the propagation characteristics and the capacity gain of the channel; under NLOS, a maximal capacity of 12.95 bits/s/Hz is achieved compared to 9.6 bits/s/Hz obtained using PMPA. For LOS and NLOS cases, maximal capacity boosts of up to 0.43 and 3.35 bits/s/Hz are achieved over PMPA, respectively.

Effect of the Receiver Attachment Position on Ultrawideband Off-Body Channels

An experimental characterization of the off-body propagation channel for the ultrawideband (UWB) band from 3.1 GHz to 8 GHz for body area networks (BAN) is presented in this letter. The channel is evaluated in terms of path loss (PL) and Root Mean Square (RMS) delay spread. Channel statistics from measurements carried out considering subjects of different gender in standing still position under line-of-sight (LOS) conditions are compared to the ones without the presence of the body to evaluate the variation on the statistics of the channel in presence of a human body. It is observed a high variation on the path loss and the RMS delay spread parameters for the same attachment position of the receiver antenna on the body of the subjects and a dependence of the statistics with the number of received multipath components (MPC) because of the shadowing effect of the body.

Effect of Antenna Position and Polarization on UWB Propagation Channel in Underground Mines and Tunnels

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.

On the Impact of Antenna Disturbances by Urban Furniture on Deterministic Propagation Simulations

In this work, we study the impact of antenna radiation patterns disturbed by urban furniture on propagation characteristics. The propagation in urban scenario is modeled with a ray-based deterministic tool. Different base station scenarios are discussed: antenna in proximity of a wall; antenna mounted on a lamp post; and antenna on a bus stop shelter. The statistical influence of the support is evaluated comparing the results in terms of pathloss with the ones obtained when the isolated antenna radiation patterns are considered.

EXPERIMENTAL CHARACTERIZATION OF A MIMO UNDERGROUND MINE CHANNEL AT 2.45 GHZ

In this paper, an experimental characterization of a MIMO underground channel is presented. A simple statistical model is proposed at 2.45GHz. The channel is characterized in terms of path loss, shadowing, RMS delay spread, and capacity. The measurements are carried out in an underground mine, which is a harsh conflned environment. The path loss model is extracted from measured data for the line of sight (LOS) and non-line of sight (NLOS) scenarios for both MIMO and SISO channels. The path loss exponent in LOS is less than 2 in MIMO and SISO as the environment has a dense concentration of scatterers. A statistical study is carried out to flnd the delay spread. For MIMO and SISO, there is no relation between the delay spread and the transmitter receiver distance. Furthermore, the delay spread of the MIMO is less than the one of the SISO channel in the LOS measurement campaigns. Aikake information criteria are used as a goodness of flt for difierent statistical distributions to represent the delay spread. According to the calculated capacity for a constant signal to noise ratio in LOS case, the transmission performance is signiflcantly improved by using the MIMO scheme over the traditional SISO. Therefore, MIMO is an ideal candidate for future wireless underground communications.