Realistic Propagation Conditions Research Articles

Dual-Slope Path Loss Model for Integrating Vehicular Sensing Applications in Urban and Suburban Environments.

The development of intelligent transportation systems (ITS), vehicular ad hoc networks (VANETs), and autonomous driving (AD) has progressed rapidly in recent years, driven by artificial intelligence (AI), the internet of things (IoT), and their integration with dedicated short-range communications (DSRC) systems and fifth-generation (5G) networks. This has led to improved mobility conditions in different road propagation environments: urban, suburban, rural, and highway. The use of these communication technologies has enabled drivers and pedestrians to be more aware of the need to improve their behavior and decision making in adverse traffic conditions by sharing information from cameras, radars, and sensors widely deployed in vehicles and road infrastructure. However, wireless data transmission in VANETs is affected by the specific conditions of the propagation environment, weather, terrain, traffic density, and frequency bands used. In this paper, we characterize the path loss based on the extensive measurement campaign carrier out in vehicular environments at 700 MHz and 5.9 GHz under realistic road traffic conditions. From a linear dual-slope path loss propagation model, the results of the path loss exponents and the standard deviations of the shadowing are reported. This study focused on three different environments, i.e., urban with high traffic density (U-HD), urban with moderate/low traffic density (U-LD), and suburban (SU). The results presented here can be easily incorporated into VANET simulators to develop, evaluate, and validate new protocols and system architecture configurations under more realistic propagation conditions.

Coverage Improvements for Sub-Terahertz Systems Under Shadowing Conditions

Radio propagation in the millimeter wave and sub-terahertz domain is heavily affected by shadowing conditions. The communication link is blocked without any additional technical means being used. Coverage improvements can be provided by using reflectors, RIS arrays, and repeaters to direct radio waves around corners or obstacles. These concepts show different performance and complexity levels affecting their network deployment. This paper investigates the achievable radio range or the received power to compare specific deployment concepts under realistic propagation conditions. Overall, the repeater solution provides either the largest radio range or the lowest necessary total transmit power compared to reflectors or RIS arrays and, thereby, is the most sustainable approach. A RIS array requires an additional centralized signal processing capacity for calculating optimized RIS settings and results in the highest level of network deployment complexity.

Monitoring of Indonesian volcanoes with the IS06 infrasound array

Detecting and notifying ongoing volcanic explosive eruptions is crucial in supporting the Volcanic Ash Advisory Centre (VAAC). However, local monitoring systems are missing at many active volcanoes, but long range infrasound monitoring might provide useful information if able to detect and notify volcanic explosive events. Indeed, many studies have already highlighted the utility and the potential of long-range infrasound monitoring for this aim, but still open questions remain concerning its actual efficiency and reliability. In this study we investigate the potential of the IS06 array (Cocos Island, Australia) of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) to remotely detect volcanic explosive eruptions in the Indonesian Arc between 2012 and 2019, when 11 volcanoes, positioned at a distance between 1000 and 2000 km from the array, erupted with an energy spanning from mild explosions to VEI (Volcanic Explosivity Index) 4 eruptions. For each volcano, using infrasonic data recorded at a single array and accounting for realistic infrasound propagation conditions, we calculate a range corrected Infrasound Parameter (IP) and propose two additional empirical thresholds on signal strength and persistency. The IP is used eventually to define an alert whenever an established threshold is exceeded and the corresponding reliability estimated. Results show that the range corrected IP is highly reliable for events VEI = 3 or greater under favorable propagation conditions, but smaller scale short-lasting explosive eruptions still remain usually undetected. Unresolved ambiguity remains due to short spacing among volcanoes with respect to the array. For regional scale monitoring purposes, this can be solved only considering volcanic sectors rather than single volcanic edifices that, despite preventing unambiguous notification of a given volcano, might allow to increase the attention of the VAAC over a specific area.

Over-the-air testing for dual-polarized MIMO devices: Setup design and validation

Over-the-air (OTA) testing is considered as the only feasible solution to evaluate radio performances of the fifth-generation (5G) wireless devices which feature two important technologies, i.e., massive multiple-input multiple-output (MIMO) and millimeter-wave (mmWave). The multi-probe anechoic chamber (MPAC) based OTA setup is able to emulate realistic multipath propagation conditions in a controlled manner. This paper investigates an MPAC OTA setup which is capable of evaluating the performances of 5G base stations as the devices-under-test (DUTs) which are equipped with dual-polarized antennas. Both end-to-end setup and probe configuration for the considered MPAC setup will be elaborated. Furthermore, since building a practical MPAC setup is expensive, time-consuming, and error-prone, an end-to-end software testbed is established for validation purpose to avoid technical risks before finalizing an MPAC setup. The architecture of the testbed is presented, which can emulate both the channel profiles perceived by the DUT and the physical-layer behaviors of the considered link conforming to 5G new radio (NR) specifications. Results show that the performances under the emulated channel agree well with those under the target channel, validating the accuracy and effectiveness of the MPAC method.

Co-Design of Consensus-Based Approach and Reliable Communication Protocol for Vehicular Platoon Control

Automated and coordinated vehicle platoon driving is challenging as the complexity of vehicle control and the presence of unreliable wireless inter-vehicle communication. This subject has an interdisciplinary nature, involving control theories, vehicle dynamics, and communication. Due to the constant interaction between control logic and communication topology, a co-design approach for the controller and for reliable communication protocol becomes necessary. This paper describes the AddP-CACC - a consensus-based solution to vehicle platoons. The proposed solution turns the communication topology into a design parameter that dynamically reconfigures the controller. In addition, the controller automatically compensates for outdated information caused by network losses and delays. AddP-CACC was implemented in the PLEXE tool and was compared with other related works. Simulation results have shown the robustness and performance of the proposed solution in various scenarios that would include realistic propagation conditions with interference caused by other vehicles. The results have also evidenced the ability of the proposed solution to maintain a stable vehicular platoon by using different communication topologies, different vehicle flows, even in the presence of strong interferences, delays, and fading conditions.

Information-Theoretic Security of MIMO Networks Under $\kappa$-$\mu$ Shadowed Fading Channels

This paper investigates the impact of realistic propagation conditions on the achievable secrecy performance of multiple-input multiple-output systems in the presence of an eavesdropper (Eve). Specifically, we concentrate on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> shadowed fading model because its physical underpinnings capture a wide range of propagation conditions, while, at the same time, it allows for a much better tractability than other state-of-the-art fading models. By considering transmit antenna selection and maximal ratio combining reception at the legitimate (Bob) and Eve's receiver sides, we study two relevant scenarios: 1) the transmitter knows Bob's channel state information (CSI) but not Eve's CSI, and 2) the transmitter is aware of the CSI of both Bob and Eve channels. For this purpose, we first obtain novel and tractable expressions for the statistics of the maximum of independent and identically distributed (i.i.d.) variates related to the legitimate channel. Based on these results, we derive novel closed-form expressions of the two aforementioned scenarios to assess the secrecy performance of the underlying system. Specifically, for cases: 1) the secrecy outage probability (SOP), the probability of strictly positive secrecy capacity (SPSC), and 2) the average secrecy capacity (ASC). Moreover, we develop analytical asymptotic expressions of the SOP and ASC in the high signal-to-noise ratio regime. In all instances, secrecy performance metrics are characterized in closed-form, without requiring the evaluation of Meijer-G or Fox-H functions. Some useful insights on how the different propagation conditions and the number of antennas impact the secrecy performance are also provided.

Spatial fading channel emulation for over-the-air testing of millimeter-wave radios: concepts and experimental validations

Millimeter-wave (mmWave) communication is regarded as the key enabling component for fifth-generation (5G) cellular systems due to the large available spectrum bandwidth. To make mmWave new radio (NR) a reality, tremendous efforts have been exerted from the industry and academia. Performance evaluation of mmWave NR is a mandatory step and the key to ensuring the success of mmWave 5G deployment. Over-the-air (OTA) radiated method of testing mmWave NR in laboratory conditions is highly attractive, since it facilitates virtual field testing of mmWave devices in realistic propagation conditions. In this paper, we first discuss the need for and challenges in OTA measurement of mmWave 5G NR under fading channel conditions. After that, two promising candidate solutions, i.e., wireless cable and multi-probe anechoic chamber (MPAC), are detailed. Their principles, applicability for mmWave NR, and main challenges are discussed. Furthermore, preliminary experimental validation results in a frequency range 2 anechoic chamber are demonstrated for the wireless cable and MPAC methods at 28 GHz.

On The Secrecy Performance Over N-Wave With Diffuse Power Fading Channel

We investigate the realistic propagation conditions effects on wireless physical layer security, which are different from classical Rice and Rayleigh fading. Specifically, we study how the superposition of a number of dominant specular waves and diffusely propagating components impacts the achievable secrecy performance. We derive analytical expressions for the secrecy outage probability and the average secrecy capacity, which have similar complexity to other alternatives in the literature derived for simpler fading models. We provide very useful insights on the impact on physical layer security of $(i)$ the number; $(ii)$ the relative amplitudes and $(iii)$ the overall power of the dominant specular components. We show that it is possible to obtain remarkable improvements on the system secrecy performance when: $(a)$ the relative amplitudes of the dominant specular components for the legitimate channel are more unbalanced compared to those of the eavesdropper's channel, and $(b)$ the power of the dominant components for the main channel is significantly larger than the power of the dominant components for the wiretap channel.

Spiny lobster sounds can be detectable over kilometres underwater

The detection ranges of broadband sounds produced by marine invertebrates are not known. To address this deficiency, a linear array of hydrophones was built in a shallow water area to experimentally investigate the propagation features of the sounds from various sizes of European spiny lobsters (Palinurus elephas), recorded between 0.5 and 100 m from the animals. The peak-to-peak source levels (SL, measured at one meter from the animals) varied significantly with body size, the largest spiny lobsters producing SL up to 167 dB re 1 µPa2. The sound propagation and its attenuation with the distance were quantified using the array. This permitted estimation of the detection ranges of spiny lobster sounds. Under the high ambient noise conditions recorded in this study, the sounds propagated between 5 and 410 m for the smallest and largest spiny lobsters, respectively. Considering lower ambient noise levels and different realistic propagation conditions, spiny lobster sounds can be detectable up to several kilometres away from the animals, with sounds from the largest individuals propagating over 3 km. Our results demonstrate that sounds produced by P. elephas can be utilized in passive acoustic programs to monitor and survey this vulnerable species at kilometre scale in coastal waters.

Coverage Analysis for 2D/3D Millimeter Wave Peer-to-Peer Networks

This paper presents a theoretical analysis for estimating the coverage probability in two-dimensional (2D) and three-dimensional (3D) peer-to-peer (P2P) millimeter-wave (mmWave) wireless networks. The analysis is carried out by adopting suitable link state models and realistic propagation conditions, involving path-loss attenuation, angular dispersion, mid- and small-scale fading, which comply with recent channel measurements. The presented framework accounts in detail for the actual shape of the transmitting/receiving antenna patterns and for the spatial statistic that describes the node location, by considering the widely adopted Poisson point process, the uniform distribution, and the random waypoint mobility model. Analytical expressions for the statistic of the received power and simple integral formulas for the coverage probability in the presence of interference and noise are derived. The accuracy of the obtained estimations and of the introduced approximations is checked by independent Monte Carlo validations. As possible applications in the 3D mmWave context, the conceived mathematical theory is used to discuss the impact of the interference model on the reliability of the noise-limited approximation, and to estimate the average link capacity of an interfered P2P communication.

On the performance of wireless sensor network time difference of arrival localization under realistic interference and timing estimation errors

The article addresses the modeling and performance analysis of wireless sensor network localization with direct-sequence spread-spectrum signals and network-based, time difference of arrival measurements. Realistic radio channel propagation and interference conditions are taken into account. Synchronization by means of a delay-locked loop is adopted for sensor signal tracking at the wireless sensor network anchor nodes. A comprehensive timing estimation analysis is presented with channel impairments, including pathloss attenuation, shadowing, multipath fading, and multi-access interference. The full statistics of the delay-locked loop tracking jitter are derived, which serves to assess the practically achievable synchronization accuracy and its variability with radio channel conditions and specific sensor location. The time difference of arrival measurements are then used for sensor localization based on an efficient iterative maximum likelihood estimation approach shown to outperform weighted least squar...

A Nonisovelocity Geometry-Based Underwater Acoustic Channel Model

This paper proposes a new geometry-based shallow underwater acoustic (UWA) channel model allowing for nonisovelocity ocean conditions. The fact that the isovelocity assumption does not hold in many real-world scenarios motivates the need for developing channel models for nonisovelocity UWA propagation environments. Starting from a geometrical model, we develop a stochastic channel model for a single-input single-output (SISO) vehicle-to-vehicle UWA channel assuming that the ocean surface and bottom are rough and that the speed of sound varies with depth. The effect of the nonisovelocity condition has been assessed regarding its influence on the temporal autocorrelation function, the frequency correlation function (FCF), and the power delay profile of the UWA channel model. The UWA channel model has also been validated by matching its FCF as well as the therefrom derived main characteristic quantities, such as the average delay, delay spread, and coherence bandwidth against measurement data. The proposed UWA channel model is very useful for the design and performance analysis of UWA communication systems under realistic propagation conditions.

A Consensus-Based Approach for Platooning with Intervehicular Communications and Its Validation in Realistic Scenarios

Automated and coordinated vehicles' driving (platooning) is very challenging due to the multibody control complexity and the presence of unreliable time-varying wireless intervehicular communication (IVC). We propose a novel controller for vehicle platooning based on consensus and analytically demonstrate its stability and dynamic properties. Traditional approaches assume the logical control topology as a constraint fixed a priori , and the control law is designed consequently; our approach makes the control topology a design parameter that can be exploited to reconfigure the controller, depending on the needs and characteristics of the scenario. Furthermore, the controller automatically compensates outdated information caused by network losses and delays. The controller is implemented in Plexe , which is a state-of-the-art IVC and mobility simulator that includes basic building blocks for platooning. Analysis and simulations show the controller robustness and performance in several scenarios, including realistic propagation conditions with interference caused by other vehicles. We compare our approach against a controller taken from the literature, which is generally considered among the most performing ones. Finally, we test the proposed controller by implementing the real dynamics (engine, transmission, braking systems, etc.) of heterogeneous vehicles in Plexe and verifying that platoons remain stable and safe, regardless of real-life impairments that cannot be modeled in the analytic solution. The results show the ability of the proposed approach to maintain a stable string of realistic vehicles with different control-communication topologies, even in the presence of strong interference, delays, and fading conditions, providing higher comfort and safety for platoon drivers.

Cooperative Awareness in the Internet of Vehicles for Safety Enhancement

Connected vehicles will improve safety and enable new services to drivers and passengers. One of the main enabled services will be the cooperative awareness, that is the broadcast transmission of periodic messages containing updated information on status and movements. This continuos communication may help the drivers in critical situations and eventually enable vehicles to autonomously coordinate their actions. Being IEEE 802.11p still the de-facto standard for vehicle-to-vehicle (V2V) communications, in this paper we investigate its performance for cooperative awareness through large scale simulations involving hundred of nodes under various settings, and considering the combinations of different modulations and coding schemes. Results highlight the effect of traÿc density, obstacles, and physical layer settings on both the reception reliability and the delay of information update, giving guidelines for the system design under realistic propagation and road traffic conditions.

Spatial Multiplexing of QPSK Signals With a Single Radio: Antenna Design and Over-the-Air Experiments

The paper describes the implementation and performance analysis of the first fully-operational beam-space MIMO antenna for the spatial multiplexing of two QPSK streams. The antenna is composed of a planar three-port radiator with two varactor diodes terminating the passive ports. Pattern reconfiguration is used to encode the MIMO information onto orthogonal virtual basis patterns in the far-field. A measurement campaign was conducted to compare the performance of the beam-space MIMO system with a conventional 2-by-?2 MIMO system under realistic propagation conditions. Propagation measurements were conducted for both systems and the mutual information and symbol error rates were estimated from Monte-Carlo simulations over the measured channel matrices. The results show the beam-space MIMO system and the conventional MIMO system exhibit similar finite-constellation capacity and error performance in NLOS scenarios when there is sufficient scattering in the channel. In comparison, in LOS channels, the capacity performance is observed to depend on the relative polarization of the receiving antennas.

A Cluster-Based Energy-Efficient Resource Management Scheme for Ultra-Dense Networks

Ultra-dense networks (UDNs), which can provide extremely high throughput and data rates, have been considered as one of the key techniques for the fifth generation mobile networks. However, it may cause severe inter-cell interference and significant energy consumption due to numerous base stations (BSs) being randomly deployed. To mitigate the interference and boost energy efficiency (EE) of the UDN effectively, we propose a cluster-based energy-efficient resource allocation scheme in this paper. The proposed scheme has two stages: clustering stage and resource allocation stage. In clustering stage, we use a modified K-means algorithm in BS-clustering process to dynamically adjust the number of BS-clusters based on the density of BSs. Then, in each BS cluster, we divide user equipments (UEs) into multiple UE-groups with minimum intra-cluster interference. In this way, the complexity of resource allocation can be greatly reduced. While in resource allocation stage, we design a two-step resource blocks assignment algorithm and an iterative energy efficient power allocation algorithm based on a non-cooperative game. Furthermore, we implement simulations under the realistic broadband channel propagation conditions and the simulation results show that the proposed approach can effectively mitigate the interference and improve the EE of UDN.

A SRM Applied in Wind Generation at Smart Grids Employing Wireless Power Control

The wind energy generation is the huge driver behind the push for supergrids and cross-border infrastructure for renewable energy systems into smart grids. To provide balance supply, demand, and storage of energy over a region in a much more efficient manner than it is done today, smart grids will need to use an advanced communication infrastructure into a robust control system. Towards this objective, it is proposed in this work a wireless coded power control employing low density parity check coding for a switched reluctance machine applied in wind generation to improve system robustness and reliability. The performance improvements of the proposed system are investigated in a more realistic frequency selective fading propagation condition.

Analyzing the Impact of Inter Cooperation Region Interference in Coordinated Multi-Point Uplink Networks

We analyze the uplink of coordinated multi-point (CoMP) networks in which cooperation can be amongst $N=2$ or $N=3$ base stations (BSs). We consider a 2-D network of BSs on a regular hexagonal lattice wherein the cooperation tessellates the 2-D plane into cooperation regions (CRs); specifically, we analyze the impact of the interference between the CRs in the network. Our model accounts realistic propagation conditions, particularly including shadowing. We obtain accurate, closed-form, approximations for the user capacity coverage probability (CCP) and the ergodic capacity at each point within the CR. To provide a network-level analysis, we focus on the locations within each CR with the minimum CCP—“the worst-case point(s)”. The worst-case CCP and/or ergodic capacity can be used in parametric studies for network design. Here, the analysis is applied to obtain the relationship between cell size and CCP and, thereby, the required density of BSs to achieve a chosen target capacity coverage. The analysis also allows for a comparison between different orders of BS cooperation, quantifying the reduced required BS density from higher orders of cooperation. Comprehensive simulations are used to illustrate the accuracy of our analysis, including the approximations used for analytic tractability.

A formula for human average whole-body SARwb under diffuse fields exposure in the GHz region

A simple formula to determine the human average whole-body SAR (SARwb) under realistic propagation conditions is proposed in the GHz region, i.e. from 1.45 GHz to 5.8 GHz. The methodology is based on simulations of ellipsoidal human body models. Only the exposure (incident power densities) and the human mass are needed to apply the formula. Diffuse scattered illumination is addressed for the first time and the possible presence of a Line-of-Sight (LOS) component is addressed as well. As validation, the formula is applied to calculate the average whole-body SARwb in 3D heterogeneous phantoms, i.e. the virtual family (34 year-old male, 26 year-old female, 11 year-old girl, and 6 year-old boy) and the results are compared with numerical ones—using the Finite-Difference Time-Domain (FDTD) method—at 3 GHz. For the LOS exposure, the average relative error varies from 28% to 12% (resp. 14–12%) for the vertical polarization (resp. horizontal polarization), depending on the heteregeneous phantom. Regarding the diffuse illumination, relative errors of −39.40%, −11.70%, 10.70%, and 10.60% are obtained for the 6 year-old boy, 11 year-old girl, 26 year-old female, and 34 year-old male, respectively. The proposed formula estimates well (especially for adults) the SARwb induced by diffuse illumination in realistic conditions. In general, the correctness of the formula improves when the human mass increases. Keeping the uncertainties of the FDTD simulations in mind, the proposed formula might be important for the dosimetry community to assess rapidly and accurately the human absorption of electromagnetic radiation caused by diffuse fields in the GHz region. Finally, we show the applicability of the proposed formula to personal dosimetry for epidemiological research.

Exact Error Rate Analysis of MIMO-MRC System under Cochannel Interference and Imperfect Channel State Information

In this paper, we derive closed-form solution for the bit error rate of multi-input multi-output (MIMO) system with maximum ratio combining. We consider binary PSK modulation suffers from cochannel interference (CCI) and imperfect channel state information (CSI). We assume a propagation model wherein the desired and interfering signals undergo independent and identically distributed (i.i.d.) Rayleigh fading channels. Furthermore, the signal-to-noise ratio (SNR) gain penalty caused by the interference signals and the root mean square of the CSI were demonstrated. The numerical results presented in this paper demonstrate the system performance under very realistic propagation and detection conditions including MIMO system, CCI, imperfect CSI, generalized fading channels, and AWGN. Hence our results are expected to be of significant practical use for such scenarios.