Radio Propagation Loss Research Articles

A three‐dimensional parabolic equation with fast reordered‐alternate direction decomposition in atmosphere duct environment

AbstractIn the design and optimisation of marine wireless communication and navigation systems, a thorough investigation of radio wave propagation characteristics under atmospheric ducting conditions is essential. The authors aim to enhance the efficiency of radio wave propagation loss prediction in marine atmospheric ducting environments, proposing a prediction model based on Fast Reordered‐Alternate Direction Decomposition (FR‐ADD). By approximating the diffraction term into three independent components, exploiting the commutative properties of the Fourier transform to reduce the spatial dimensions, and incorporating a rapid algorithm for the parabolic equation, the model optimises the stepping process and significantly improves computational efficiency. Simulation experiments demonstrate that, in the long‐distance and complex marine ducting environments, the model not only maintains prediction accuracy but also substantially reduces computational load and prediction time, effectively realising over‐the‐horizon propagation prediction. In the experiment of radio wave propagation characteristics in the Yellow and Bohai Seas, the simulation data from the FR‐ADD model showed significant correlation with actual measurements and simulations from the AREPS software, confirming the method's efficiency and practicality.

The Influence of PE Initial Field Construction Method on Radio Wave Propagation Loss and Tropospheric Duct Inversion

Parabolic equations (PE) are commonly employed for calculating the spatial propagation loss of wireless signals. The initial field is a crucial factor. To investigate the impact of construction accuracy on the calculation of radio wave propagation loss, we selected the half-wave dipole antenna and its Gaussian approximation to examine the influence of wide-angle PE modeling. We analyzed the disparities between the actual antenna pattern and the Gaussian beam approximation, as well as the discrepancies in the corresponding initial field and the calculation of radio wave propagation loss in PE modeling. The simulation results indicate that the error of the Gaussian approximation increases as the angle of departure from the antenna main beam increases, with a relative error of approximately 30% in the initial field. A comparison between the experimental test of the broadcast signal and the simulation calculation reveals that the model based on the actual antenna aligns more closely with the measured value on a flat underlying surface. However, in mountainous areas with significant fluctuations, the simulation results are consistent with each other and higher than the measured value. The inversion results obtained through the particle swarm optimization algorithm demonstrate that the model based on the actual antenna exhibits superior inversion accuracy for the tropospheric atmospheric duct structure.

The Analysis and Verification of IMT-2000 Base Station Interference Characteristics in the FAST Radio Quiet Zone

In this study, we aim to analyze the electromagnetic interference (EMI) regarding the Five-hundred-meter Aperture Spherical radio Telescope (FAST) caused by base stations in the International Mobile Telecommunications-2000 (IMT-2000) frequency band. By analyzing the frequency bands used by the transmitting and receiving devices and the surrounding environmental parameters and utilizing an approach to predicting radio wave propagation loss that is based on deterministic methods, we conclude by comparing the predicted received power at the FAST with its interference protection threshold. Our analysis demonstrates that, currently, only 55.31% of IMT-2000 base stations in the FAST radio quiet zone (RQZ) meet the protection threshold. Additionally, this article verifies the applicability and accuracy of the radio wave propagation model used in the research based on field strength measurements. Overall, this study provides valuable insights for improving the electromagnetic environment surrounding FAST and reducing the EMI caused by mobile communication base stations. It also provides corresponding analysis methods and useful suggestions for analyzing electromagnetic radiation interference in other radio telescopes.

Evaluation of the Use of M2M-Type NB-IoT and LTE Technologies for Maritime Communication Systems

Abstract The development of IoT (the Internet of Things) wireless transmission opens a new era in communication systems. In the next years, the development and implementation of IoT systems will be very dynamic. It can be seen that the solutions of LTE – NB-IoT (Long Term Evolution – Narrowband IoT) transmission devices are implemented in a wide range of terrestrial solutions, e.g. smart grids. This paper aims to analyse the possibility of the use of NB-IoT technology for maritime communication applications and partially, for some maritime safety solutions, based on signal coverage analysis at sea. An interesting approach is the comparison of the results of NB-IoT coverage to the classic cellular LTE-based communication systems. Proposed solutions are based on the practical implementation of a designed specialised data concentrator with implemented gateway and radio modems, for both NB-IoT technology as well as LTE. In the paper, analyses of radio link budget and propagation loss models for sea environment are presented. The coverage analysis is based on real measurements of the efficiency of transmissions using wireless modems implemented in the developed data concentrator.

An Accurate Maritime Radio Propagation Loss Prediction Approach Employing Neural Networks

The radio propagation loss prediction model is essential for maritime communication. The oceanic tropospheric duct is much more complicated than the atmospheric structure on land due to the rough sea surface influence, and it leads to difficulties in loss prediction. Classical radio wave propagation loss prediction models are either based on complicated electromagnetic wave theories or rely on empirical data. Consequently, they suffer from low accuracy and a limited range of application. To address this issue, a novel maritime propagation loss prediction approach is proposed, which fully exploits the data for training. In this new approach, 3D sea surface contour profiles are generated based on the Pierson–Moskowitz spectrum theory and the direction expansion formula Stereo Wave Observation Program (SWOP), by sweeping the parameters. The full-wave propagation procedure of radio signals over the sea surface is simulated by commercial EM analysis software CST Studio Suite. Based on the large quantity of simulated data, the BP neural network is employed to fit the radio propagation loss and obtain the sea surface radio wave propagation prediction model. Other classical machine learning methods are also compared to validate the proposed approach. Traditional empirical model construction relies on observation data. This approach, for the first time, proposed an automatic scheme which covers the whole procedure from the data generation to prediction model training. It avoids the requirements for on-site observation, as well as significantly decreases the cost of experiments. The application scope of the prediction model such as propagation distance range and working frequency range could be adaptive through adjustments for simulated sea size and simulated working frequency. This approach is validated to save 99% of prediction time in comparison with the full-wave simulations. The prediction model trained via our proposed method could obtain the coefficient of determination R2 which is over 0.92, demonstrating the superiority of this method.

WLAN RSS-Based Fingerprinting for Indoor Localization: A Machine Learning Inspired Bag-of-Features Approach.

Location-based services have permeated Smart academic institutions, enhancing the quality of higher education. Position information of people and objects can predict different potential requirements and provide relevant services to meet those needs. Indoor positioning system (IPS) research has attained robust location-based services in complex indoor structures. Unforeseeable propagation loss in complex indoor environments results in poor localization accuracy of the system. Various IPSs have been developed based on fingerprinting to precisely locate an object even in the presence of indoor artifacts such as multipath and unpredictable radio propagation losses. However, such methods are deleteriously affected by the vulnerability of fingerprint matching frameworks. In this paper, we propose a novel machine learning framework consisting of Bag-of-Features and followed by a k-nearest neighbor classifier to categorize the final features into their respective geographical coordinate data. BoF calculates the vocabulary set using k-mean clustering, where the frequency of the vocabulary in the raw fingerprint data represents the robust final features that improve localization accuracy. Experimental results from simulation-based indoor scenarios and real-time experiments demonstrate that the proposed framework outperforms previously developed models.

A novel in vivo 433 MHz radio channel indoor study targeting on power saving for ruminal health monitoring boluses

Ruminal indwelling wireless sensor node is a promising device that combines telemetry and biosensing techniques. However, lack of adequate numerical tools and mathematical models to analyze the in-to-out body radio propagation is hindering further development of such devices. In this study, a new approach to investigate the 433 MHz radio propagation channel between a ruminal sensor node and a wearable receiver is proposed. Unlike theoretical channel modeling methods, time-variant features and influences from digestive activities were modeled and examined in this study. A circadian path loss pattern was generated through continuous observation, which illustrated how radio signals from the ruminal sensor node were attenuated with the rumen-cannulated pilot cow in its normal status in the barn. Link viability across the day was confirmed while the period with excessive link margin was identified. Consequently, a power-reduction plan was proposed which would bring in over a 15% increase in battery life of the ruminal sensing device, which is crucial for long-term indwelling devices. Meanwhile, the methodology and cross-disciplinary approach proposed in this study to investigate the in-to-out body radio propagation loss for ruminal indwelling sensing nodes demonstrated its merit in the discovery of little-known radio channels.

3-D Simulation of MANET with UAV in Mountainous Areas

In recent years, there has been a worldwide boom in mountain climbing because the activity has become easier due to the higher functionality and lighter weight of mountaineering equipment. Along with this boom, mountain distress accidents have also increased. In the event of a disaster, effective communication with search and rescue victims is important. Mobile communication in the mountains, however, is limited because radio waves from the base station may be blocked due to topographic features, vegetation in the surrounding environment, etc. Therefore, a mobile ad hoc network (MANET) could be a useful means of communication. Recently, unmanned aerial vehicles (UAVs, e.g., drones and balloons) have become smaller and more sophisticated, with the result that UAVs could now be available as relay devices for MANETs. However, the effectiveness of MANETs in combination with UAVs in mountainous areas has not yet been clarified and no construction method has yet been established. Furthermore, in the case of mountain communication simulations, elevation differences of several thousand meters on mountain trails and radio wave propagation losses peculiar to mountains must be considered, as these conditions differ from those of common MANET simulations. Therefore, in this study, we simulated 3-dimensional MANET with UAVs using the Hotaka mountain range as an example case. Our radio wave propagation model includes the 2-ray ground reflection model, the double knife-edge diffraction loss model, and the standard model of vegetation attenuation. We simulated communication between a climber and a basecamp or hut on the mountain by MANET relayed by drones and a balloon in four scenarios, finding that the UAV expands the communicable area substantially in the mountains. We also examined the influence of rainfall and snow on mountain MANET communication.

МОДЕЛИРОВАНИЕ СВЕРХПЛОТНЫХ СЕТЕЙ РАДИОДОСТУПА 5G С ДИАГРАММООБРАЗОВАНИЕМ

In this paper, we investigate the connectivity and probability of successful radio reception in the Poisson model of a 5G ultra-dense radio access network formed by devices with the possibility of location aware beamforming. The difference be-tween the proposed model and the existing prototypes is the complex account for the gains of devices, as well as the influence of radio wave propagation losses, slow and fast fading in the radio channel on the performance of the radio access network. The study is carried out for sessions of directional and omni-directional radio communication, and the beamforming mode is based on the preliminary positioning of neighboring devices. Mathematical modeling of a set of simultaneously operating radio lines in the Poisson model of an ultra-dense 5G radio access network makes it possible to estimate the gain in connectivity and the probability of successful radio reception when forming a beam based on preliminary positioning of devices in comparison with the case of omnidirectional antennas. The results of mathematical modeling of a ultra-dense radio access network with devices equipped with six-element circular antenna arrays showed a significant increase in connectivity indicators and the probability of successful radio reception in comparison with the case of omnidirectional antennas and confirmed the possibility of spatial multiplexing of simultaneous transmissions with a territorial separation of devices on 20% of the range of radio coverage based on the signal-to-noise ratio criterion. The result of the study is the establishment of the dependences of the connectivity and the probability of successful radio reception for an ultra-dense 5G radio access network, built on the basis of devices operating in the adaptive diagramming mode, as well as confirmation of the possibilities of spatial multiplexing of simultaneously operating transceiver devices with their territorial separation by 20% of the range of radio coverage based on the signal-to-interference ratio criterion. The obtained dependences of connectivity and the probability of successful radio reception allows to scientifically substantiate construction of an initial approximation of ultra-dense 5G radio access network from devices with the possibility of beamforming based on positioning, taking into account practical recommendations for their territorial diversity with an ultra-dense distribution.

Design, Implementation, and Empirical Validation of an IoT Smart Irrigation System for Fog Computing Applications Based on LoRa and LoRaWAN Sensor Nodes.

Climate change is driving new solutions to manage water more efficiently. Such solutions involve the development of smart irrigation systems where Internet of Things (IoT) nodes are deployed throughout large areas. In addition, in the mentioned areas, wireless communications can be difficult due to the presence of obstacles and metallic objects that block electromagnetic wave propagation totally or partially. This article details the development of a smart irrigation system able to cover large urban areas thanks to the use of Low-Power Wide-Area Network (LPWAN) sensor nodes based on LoRa and LoRaWAN. IoT nodes collect soil temperature/moisture and air temperature data, and control water supply autonomously, either by making use of fog computing gateways or by relying on remote commands sent from a cloud. Since the selection of IoT node and gateway locations is essential to have good connectivity and to reduce energy consumption, this article uses an in-house 3D-ray launching radio-planning tool to determine the best locations in real scenarios. Specifically, this paper provides details on the modeling of a university campus, which includes elements like buildings, roads, green areas, or vehicles. In such a scenario, simulations and empirical measurements were performed for two different testbeds: a LoRaWAN testbed that operates at 868 MHz and a testbed based on LoRa with 433 MHz transceivers. All the measurements agree with the simulation results, showing the impact of shadowing effects and material features (e.g., permittivity, conductivity) in the electromagnetic propagation of near-ground and underground LoRaWAN communications. Higher RF power levels are observed for 433 MHz due to the higher transmitted power level and the lower radio propagation losses, and even in the worst gateway location, the received power level is higher than the sensitivity threshold (−148 dBm). Regarding water consumption, the provided estimations indicate that the proposed smart irrigation system is able to reduce roughly 23% of the amount of used water just by considering weather forecasts. The obtained results provide useful guidelines for future smart irrigation developers and show the radio planning tool accuracy, which allows for optimizing the sensor network topology and the overall performance of the network in terms of coverage, cost, and energy consumption.

Correlation between Railway Cutting Scenarios Parameters and Wireless Path Loss Exponent

ABSTRACT Due to the particularity of radio wave propagation characteristics in railway scenarios, the relationship between the scenarios and radio wave propagation loss has yet to be studies. In this paper, several common wireless channel path loss models of public network and the path loss measurement data of railway deep cutting scenarios are compared and analyzed, the correlation degree between the structural parameters and the path loss exponent of cutting scenarios is calculated, and the correlation between the parameters of cutting scenarios and ideal cutting scenarios is analyzed. The preliminary conclusion is that the Hata model in open ground environment conforms better to the path loss characteristics of the high-speed railway’s cutting scenario. The width of width sum and the width difference between crown and bottom of cutting scenarios are closely related to the path loss exponent. And the path loss exponent is more reasonable when the cutting scenarios parameters are within a certain range. The research results have some guiding significance for the collaborative work between cutting scenarios construction and wireless network construction.

Power optimization of invivo sensor node operating at terahertz band using PSO

The invivo nano-communication links at terahertz (THz) frequencies needs high transmit power because signal suffers radio propagation losses through biological tissues. Less power is received by on body receiving node due to the absorption noise inside the human body. Transmit power of an invivo sensor node needs to be minimized as high transmit power is harmful for biological tissues present inside human body. This paper has been devised with the aim to optimize (using PSO) the transmitted power of invivo sensor node operating at terahertz band. Influence of blood, skin and fat on the communicating signal in invivo communication network has been modelled to critically compare diverse modulation schemes (MFSK, MPSK, and OOK) and compute received power by an on body sensor node. Threshold distance between two communicating nodes is computed using eigen values and is further used as a constrain for PSO to optimize transmitted power of invivo sensor node.

On the Performance of LMS Communication With Hardware Impairments and Interference

This paper investigates the performance of a dual-hop decode-and-forward (DF) relaying-aided land mobile satellite communication over Shadowed-Rician (SR) fading channels. A practical model for the satellite relaying system is first developed, where the impacts of satellite multi-beam antenna, radio propagation loss, and random shadowing are taken into account. Next, by assuming that the multi-beam satellite suffers from hardware impairments (HIs) and is perturbed by interference signals, we derive an equivalent end-to-end signal-to-interference-plus-noise-and-distortion-ratio of the system, and justify that the maximum ratio transmission at the source and the maximum ratio combining at the destination are the optimal transmit-receive beamforming schemes on the proposed HIs model. Then, closed-form expressions for the probability density function (PDF) of the sum of independent and identically distributed (i.i.d) squared SR random variables in the case of integer and rational Nakagami-m fading parameters are derived. Based on the derived PDF, new analytical expressions for the outage probability (OP) and average throughput are obtained in the presence of HIs and interference. Moreover, the asymptotic OP and average throughput at high signal-to-noise ratio are investigated to reveal the achievable diversity order of the system. Finally, Monte Carlo simulation results are provided to corroborate the analytical results.

A position revision method by path-loss factor in wireless sensor node deployment

In this paper, we propose a position revision of sensor node that utilises the geo-spatial information and considers the path-loss factors to reveal the radio propagation loss interfered with the major urban obstacles. First, we measure the propagation path loss about the radio frequencies in the target street of the urban, and define the correlation between the measurements and the geo-spatial characteristics for the street and its surrounding obstacle get from the geographic information system. Secondly, through the use of the correlation, we describe the detailed instruction for required to determine the radio coverage and the reliable deployment plan of the wireless node in the core area of urban. By the consideration of them, we can evaluate the communication reliability below 5 dB RMS error. And, our study can be utilised as the way to revise the deployment plan based on the path loss and can be apply to the power conservation strategy of the entire networks through transmission power adaption that is reconfigure relative to a received power.

A position revision method by path-loss factor in wireless sensor node deployment

In this paper, we propose a position revision of sensor node that utilises the geo-spatial information and considers the path-loss factors to reveal the radio propagation loss interfered with the major urban obstacles. First, we measure the propagation path loss about the radio frequencies in the target street of the urban, and define the correlation between the measurements and the geo-spatial characteristics for the street and its surrounding obstacle get from the geographic information system. Secondly, through the use of the correlation, we describe the detailed instruction for required to determine the radio coverage and the reliable deployment plan of the wireless node in the core area of urban. By the consideration of them, we can evaluate the communication reliability below 5 dB RMS error. And, our study can be utilised as the way to revise the deployment plan based on the path loss and can be apply to the power conservation strategy of the entire networks through transmission power adaption that is reconfigure relative to a received power.

Dependence of minimum propagation distance and related attenuation of radio disturbance on the density of randomly located emitters and receivers in limit setting model

The statistical properties of the minimum propagation distance and the related radio propagation loss are theoretically analyzed assuming randomly distributed disturbance sources and receivers for application to the radio-protection limit setting model. It is shown that the minimum distance follows a Rayleigh distribution whose mean-square distance is inversely proportional to the area density of the disturbance sources or that of victim receivers. By using a magnetic dipole model on a metal ground, propagation losses in the near and far fields are presented with the introduction of a piecewise approximation. On the basis of the above results, the probability density function (PDF) of the minimum propagation loss is derived and numerically calculated for various area densities and radio frequencies by a comparison with a log-normal approximation of the PDF. It is found that each PDF exhibits its maximum at a propagation loss related to the root-mean-square minimum propagation distance. The log-normal PDF demonstrates a good approximation of the exact PDF at around its maximum, and enables a rough estimation of the statistics of the propagation loss. The mean value and standard deviation of the minimum propagation loss are also presented for application to the emission limit setting model.

Realistic Indoor Radio Propagation for Sub-GHz Communication.

This research article proposes a novel ray-launching propagation loss model that is able to use an environment model that contains the real geometry. This environment model is made by applying a Simultaneous Localization and Mapping (SLAM) algorithm. As a solution to the rising demands of Internet of Things applications for indoor environments, this deterministic radio propagation loss model is able to simulate an accurate coverage map that can be used for localization applications or network optimizations. Since this propagation loss model uses a 2D environment model that was captured by a moving robot, an automated validation model is developed so that a wireless sensor network can be used for validating the propagation loss model. We validated the propagation loss model by evaluated two environment models towards the lowest Root Mean Square Error (RMSE), the Mean Absolute Error (MAE), and the Mean Error (ME). Furthermore, the correlation between the number of rays and the RMSE is analyzed and the correlation between the number of reflections versus the RMSE is also analyzed. Finally, the performance of the radio propagation loss model is analyzed.

Improving Accuracy of Ray-Tracing Prediction in Non Line-of-Sight (NLOS) Urban Street Cell Environment beyond 6GHz

Recently, mobile networks employing high-speed high-capacity communications have been investigated extensively to satisfy the demand for faster and higher-capacity data communications. In one approach, frequencies between 6 and 100GHz are candidates to utilize relatively wide frequency bandwidths. Accordingly, radio propagation loss in these frequency bands must be characterized. Ray-tracing (RT) is the most common modeling approach to predict propagation loss in site-specific scenarios. The accuracy of RT simulations has been investigated in urban street cell environments based on comparison to measurement results and we observed that the difference between RT simulation and measurement results tends to increase as the frequency increases. In this paper, we focus on the shape of building corners at an intersection because it is this shape that is a dominant contributing factor in the region away from the intersection. In order to correct the error in the conventional RT method, we propose an alternative model that considers the detailed shape of the building corner and surface roughness. The performance of the RT simulation using the proposed method is then investigated based on comparison of two different sets of measurement results. Finally, we extract the optimal size and roughness for the proposed modeling method. Consequently, we confirm that using the proposed method with optimized parameters significantly enhances the accuracy compared to the conventional method.

OPTIMISATION OF RADIO TRANSMITTER LOCATIONS IN MOBILE TELECOMMUNICATION NETWORKS

Multiple factors have to be taken into account when mobile telecommunication network providers make decisions about radio transmitter placement. Generally, area coverage and the average signal level provided are of prime importance in these decisions. These criteria give rise to a bi-objective problem of facility location, with the goal of achieving an acceptable trade-off between maximising the total area coverage and maximising the average signal level provided to the demand region by a network of radio transmitters. This paper establishes a mathematical modelling framework, based on these two placement criteria, for evaluating the effectiveness of a given set of radio transmitter locations. In the framework, coverage is measured according to the degree of obstruction of the so-called ‘Fresnel zone’ that is formed between handset and base station, while signal strength is modelled taking radio wave propagation loss into account. This framework is used to formulate a novel bi-objective facility location model that may form the basis for decision support aimed at identifying high-quality transmitter location trade-off solutions for mobile telecommunication network providers. But it may also find application in various other contexts (such as radar, watchtower, or surveillance camera placement optimisation).

Experimental Path Loss Models for In-Body Communications Within 2.36-2.5 GHz.

Biomedical implantable sensors transmitting a variety of physiological signals have been proven very useful in the management of chronic diseases. Currently, the vast majority of these in-body wireless sensors communicate in frequencies below 1GHz. Although the radio propagation losses through biological tissues may be lower in such frequencies, e.g., the medical implant communication services band of 402 to 405MHz, the maximal channel bandwidths allowed therein constrain the implantable devices to low data rate transmissions. Novel and more sophisticated wireless in-body sensors and actuators may require higher data rate communication interfaces. Therefore, the radio spectrum above 1GHz for the use of wearable medical sensing applications should be considered for in-body applications too. Wider channel bandwidths and smaller antenna sizes may be obtained in frequency bands above 1GHz at the expense of larger propagation losses. Therefore, in this paper, we present a phantom-based radio propagation study for the frequency bands of 2360 to 2400MHz, which has been set aside for wearable body area network nodes, and the industrial, scientific, medical band of 2400 to 2483.5MHz. Three different channel scenarios were considered for the propagation measurements: in-body to in-body, in-body to on-body, and in-body to off-body. We provide for the first time path loss formulas for all these cases.