During daylight hours, the concentration of electrons in the ionosphere can be amplified by solar flares, which may subsequently influence the propagation of radio waves. Previous research on Very Low Frequency (VLF) signals focused on X-class and M-class flares. This study expands the scope to include a broader frequency range and C-class flares. During 20-28 February 2014, signals from 15 transmitters (18.3—81.0 kHz) were recorded by a receiver in Bath, UK. 20 solar flares captured during this period are investigated. A new methodology was employed to determine the rise times of the received amplitudes for comparison with the solar X-ray flux recorded by the Geostationary Operational Environmental Satellite geostationary satellite. The time delays between the onset of the X-ray flux and the onset of received amplitude changes are calculated. The general trend shows that shorter delays are linearly correlated to longer rise times of the amplitudes. It is found that the absolute slopes of the linear correlation between the delay and the rise time of M-class flares are larger than those of C-class flares. Two flares showed onset times of received amplitudes preceding the X-ray flux onset. A possible explanation for this is that the received signals might also be influenced by hard X-rays rather than the analyzed soft X-rays. In summary, this study demonstrates the effects of small C-class and M- class flares on the propagation of VLF/LF signals and offers insights for further research on solar flare impacts on radio waves and the lower ionosphere.
{"title":"Correlation between the delay and rise time of VLF/LF amplitudes during 20 solar X-ray flares observed in February 2014 at mid-latitude","authors":"Y. Liu;M. Füllekrug","doi":"10.1029/2024RS008103","DOIUrl":"https://doi.org/10.1029/2024RS008103","url":null,"abstract":"During daylight hours, the concentration of electrons in the ionosphere can be amplified by solar flares, which may subsequently influence the propagation of radio waves. Previous research on Very Low Frequency (VLF) signals focused on X-class and M-class flares. This study expands the scope to include a broader frequency range and C-class flares. During 20-28 February 2014, signals from 15 transmitters (18.3—81.0 kHz) were recorded by a receiver in Bath, UK. 20 solar flares captured during this period are investigated. A new methodology was employed to determine the rise times of the received amplitudes for comparison with the solar X-ray flux recorded by the Geostationary Operational Environmental Satellite geostationary satellite. The time delays between the onset of the X-ray flux and the onset of received amplitude changes are calculated. The general trend shows that shorter delays are linearly correlated to longer rise times of the amplitudes. It is found that the absolute slopes of the linear correlation between the delay and the rise time of M-class flares are larger than those of C-class flares. Two flares showed onset times of received amplitudes preceding the X-ray flux onset. A possible explanation for this is that the received signals might also be influenced by hard X-rays rather than the analyzed soft X-rays. In summary, this study demonstrates the effects of small C-class and M- class flares on the propagation of VLF/LF signals and offers insights for further research on solar flare impacts on radio waves and the lower ionosphere.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 4","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The polarizations of ionospheric characteristic waves (CWs) are determined by the two solutions of the quadratic equation in the complex polarization ratio R within the magneto-ionic theory. This paper revisits these solutions and their relationship from the perspective of real representation, given that various real polarization parameter sets are also commonly used and play important parts in characterizing wave polarization. Multiple two-dimensional (2D) real representations are analyzed by re-examining several real two- parameter sets mathematically under a unified framework to prevent possible confusion from examining different parameters in separate frameworks, and by graphically representing the polarizations of the two CWs using 2D polarization plane plots constructed from paired real parameters. A three-dimensional (3D) real representation as the extension of two dimensions is further considered by the mathematical re-examination of the three normalized Stokes parameters for the two CWs and the application of the 3D Poincaré sphere visualization to overcome the non-uniform polarization distribution on the plane plot and the non-unique correspondence between plane point and polarization state. Each real parameter in these real representations is expressed as a function of R. Importantly, the relationship between the same real parameters of the two CWs is derived. Numerical examples presented through the polarization plane or Poincaré sphere plot demonstrate how these real parameters vary with certain ionosphere medium-related quantities and validate the correctness of the derived relationships. The comparison of each real representation with and without collisions reveals the impact of collisions on the real parameters and polarization orthogonality of the two CWs.
{"title":"Complex polarizations of ionospheric characteristic waves: A revisit in terms of real representation","authors":"Xun Wang;Yunhua Zhang;Dong Li","doi":"10.1029/2024RS008197","DOIUrl":"https://doi.org/10.1029/2024RS008197","url":null,"abstract":"The polarizations of ionospheric characteristic waves (CWs) are determined by the two solutions of the quadratic equation in the complex polarization ratio R within the magneto-ionic theory. This paper revisits these solutions and their relationship from the perspective of real representation, given that various real polarization parameter sets are also commonly used and play important parts in characterizing wave polarization. Multiple two-dimensional (2D) real representations are analyzed by re-examining several real two- parameter sets mathematically under a unified framework to prevent possible confusion from examining different parameters in separate frameworks, and by graphically representing the polarizations of the two CWs using 2D polarization plane plots constructed from paired real parameters. A three-dimensional (3D) real representation as the extension of two dimensions is further considered by the mathematical re-examination of the three normalized Stokes parameters for the two CWs and the application of the 3D Poincaré sphere visualization to overcome the non-uniform polarization distribution on the plane plot and the non-unique correspondence between plane point and polarization state. Each real parameter in these real representations is expressed as a function of R. Importantly, the relationship between the same real parameters of the two CWs is derived. Numerical examples presented through the polarization plane or Poincaré sphere plot demonstrate how these real parameters vary with certain ionosphere medium-related quantities and validate the correctness of the derived relationships. The comparison of each real representation with and without collisions reveals the impact of collisions on the real parameters and polarization orthogonality of the two CWs.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 4","pages":"1-27"},"PeriodicalIF":1.6,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Very Low Frequency (VLF, 3–30 kHz) waves propagate long distances in the waveguide formed by the Earth and the lower ionosphere. External sources such as solar flares and lightning discharges perturb the upper waveguide boundary and thereby modify the waves propagating within it. Therefore, studying the propagation of VLF waves within the waveguide enables us to probe the ionospheric response to external forcing. However, the wave propagation also depends on the lower waveguide boundary property, that is, the path conductivity. We tackle two main questions: how accurate should the path conductivity description be to obtain a given accuracy on the ionospheric electron density? Are the currently available ground-conductivity maps accurate enough? The impact of the ground conductivity values and their spatial extension on VLF wave propagation is studied through modeling with the Longwave Mode Propagator code. First, we show that knowledge of the path conductivity value should be more accurate as the ground conductivity decreases, in particular in regions where σ ≤ 10−3 S/m. Second, we find that wave propagation is strongly sensitive to the spatial extension of ground conductivity path segments: segments of a few tens of km should be included in the path description to maintain below 50% the error on the derived electron density due to the path description. These results highlight the need for an update of the ground conductivity maps, to get better spatial resolution, more accurate values, and an estimate of the time-variability of each region.
{"title":"Effect of ground conductivity on VLF wave propagation","authors":"P. Teysseyre;C. Briand;R. Marshall;M. Cohen","doi":"10.1029/2024RS008150","DOIUrl":"https://doi.org/10.1029/2024RS008150","url":null,"abstract":"Very Low Frequency (VLF, 3–30 kHz) waves propagate long distances in the waveguide formed by the Earth and the lower ionosphere. External sources such as solar flares and lightning discharges perturb the upper waveguide boundary and thereby modify the waves propagating within it. Therefore, studying the propagation of VLF waves within the waveguide enables us to probe the ionospheric response to external forcing. However, the wave propagation also depends on the lower waveguide boundary property, that is, the path conductivity. We tackle two main questions: how accurate should the path conductivity description be to obtain a given accuracy on the ionospheric electron density? Are the currently available ground-conductivity maps accurate enough? The impact of the ground conductivity values and their spatial extension on VLF wave propagation is studied through modeling with the Longwave Mode Propagator code. First, we show that knowledge of the path conductivity value should be more accurate as the ground conductivity decreases, in particular in regions where σ ≤ 10<sup>−3</sup> S/m. Second, we find that wave propagation is strongly sensitive to the spatial extension of ground conductivity path segments: segments of a few tens of km should be included in the path description to maintain below 50% the error on the derived electron density due to the path description. These results highlight the need for an update of the ground conductivity maps, to get better spatial resolution, more accurate values, and an estimate of the time-variability of each region.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 3","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vortex electromagnetic wave carries orbital angular momentum. Combined with Doppler information provided by radar platform movement, vortex electromagnetic wave can achieve higher resolution target imaging in SAR Imaging technology. In this paper, fractional order OAM vortex SAR imaging is studied. Firstly, the side-looking strip SAR imaging model is established. Then, the scattering echo equation of fractional order OAM is derived. Finally, the imaging simulation of multi-point target and single point target under Gaussian SNR is carried out by Chirp Scaling algorithm. The experimental results show that compared with the integer order OAM Vortex SAR Imaging, the fractional order OAM Vortex SAR Imaging in this paper has stronger robustness in Multi-target and Noise environment, which proves the effectiveness of the fractional order Vortex SAR Imaging.
{"title":"Fractional OAM vortex SAR imaging based on chirp scaling algorithm","authors":"Liu Yu;Du Yongxing;Li Baoshan;Qin Ling;Li Chenlu","doi":"10.1029/2024RS008112","DOIUrl":"https://doi.org/10.1029/2024RS008112","url":null,"abstract":"Vortex electromagnetic wave carries orbital angular momentum. Combined with Doppler information provided by radar platform movement, vortex electromagnetic wave can achieve higher resolution target imaging in SAR Imaging technology. In this paper, fractional order OAM vortex SAR imaging is studied. Firstly, the side-looking strip SAR imaging model is established. Then, the scattering echo equation of fractional order OAM is derived. Finally, the imaging simulation of multi-point target and single point target under Gaussian SNR is carried out by Chirp Scaling algorithm. The experimental results show that compared with the integer order OAM Vortex SAR Imaging, the fractional order OAM Vortex SAR Imaging in this paper has stronger robustness in Multi-target and Noise environment, which proves the effectiveness of the fractional order Vortex SAR Imaging.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 3","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The artificial periodic inhomogeneity (API) technique is an ionospheric modification experiment that creates perturbations in the electron plasma density, studied through the scattering of probing radio waves. This work presents the first comprehensive observation of API irregularities at the HAARP facility including responses from the D, E, and F regions. The measurements were obtained by reprocessing backscatter echoes from an experimental campaign in 2014. To investigate the evolution of these structures, we extend a one-dimensional fluid model previously developed by Hysell and Rojas (2023, https://doi.org/10.1029/2023rs007710), that simulates the formation of API in the E region, incorporating mechanisms that dominate the API formation in other regions. The creation of these irregularities in the D region is accomplished by including a simplified chemical model that contains the reactions necessary for the production of negative ions. In the F region, we consider the inclusion of the ponderomotive force, which is proposed as the primary mechanism to generate these inhomogeneities. The updated model successfully produced API irregularities in the three distinct ionospheric regions according to their respective formation mechanisms. Information about the diffusion process of these structures is obtained by analyzing their decay times.
{"title":"Modeling and analysis of artificial periodic inhomogeneities in the ionosphere","authors":"B. H. La Rosa;D. L. Hysell","doi":"10.1029/2025RS008226","DOIUrl":"https://doi.org/10.1029/2025RS008226","url":null,"abstract":"The artificial periodic inhomogeneity (API) technique is an ionospheric modification experiment that creates perturbations in the electron plasma density, studied through the scattering of probing radio waves. This work presents the first comprehensive observation of API irregularities at the HAARP facility including responses from the D, E, and F regions. The measurements were obtained by reprocessing backscatter echoes from an experimental campaign in 2014. To investigate the evolution of these structures, we extend a one-dimensional fluid model previously developed by Hysell and Rojas (2023, https://doi.org/10.1029/2023rs007710), that simulates the formation of API in the E region, incorporating mechanisms that dominate the API formation in other regions. The creation of these irregularities in the D region is accomplished by including a simplified chemical model that contains the reactions necessary for the production of negative ions. In the F region, we consider the inclusion of the ponderomotive force, which is proposed as the primary mechanism to generate these inhomogeneities. The updated model successfully produced API irregularities in the three distinct ionospheric regions according to their respective formation mechanisms. Information about the diffusion process of these structures is obtained by analyzing their decay times.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 5","pages":"1-15"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radar echo data, a refined representation of detected targets, is gaining attention in electronic warfare, marine environment monitoring, and agriculture intelligence for land cover recognition. In contrast to prevailing studies involving two-dimensional images such as synthetic aperture radar (SAR) or inverse SAR (ISAR) images, one-dimensional High-Resolution Range Profile (HRRP) data offers advantages of easy access and simple processing. Nonetheless, its potential application has yet to be explored, as current research on it remains insufficient. Meanwhile, deep learning methods that specialize in classification tasks but encounter challenges in modern electronic warfare, given their heavy reliance on the number of labeled samples. To tackle these issues, a feature fusion-based land cover recognition approach is proposed, which introduces Convolutional Embedding Sequence Encoder (CE-SE) to capture the complex clutter characteristics of HRRP, achieving land cover recognition with a small number of labeled HRRP samples and eliminating the reliance on two-dimensional image data. Experimental results validated on Mini-SAR data from unmanned aerial vehicles demonstrate effective land cover recognition using HRRP. This method significantly improves the recognition accuracy for five land cover types, exceeding 92%, even with only half the sample size compared to traditional deep learning methods. Additionally, the model's inference time for a single HRRP sample is just 1.3 milliseconds, demonstrating its capability for real-time land cover recognition.
{"title":"Land cover recognition from few samples of radar high-resolution range profile","authors":"Xinhao Xu;Shuqi Lei;Dongxiao Yue;Feng Wang","doi":"10.1029/2024RS007963","DOIUrl":"https://doi.org/10.1029/2024RS007963","url":null,"abstract":"Radar echo data, a refined representation of detected targets, is gaining attention in electronic warfare, marine environment monitoring, and agriculture intelligence for land cover recognition. In contrast to prevailing studies involving two-dimensional images such as synthetic aperture radar (SAR) or inverse SAR (ISAR) images, one-dimensional High-Resolution Range Profile (HRRP) data offers advantages of easy access and simple processing. Nonetheless, its potential application has yet to be explored, as current research on it remains insufficient. Meanwhile, deep learning methods that specialize in classification tasks but encounter challenges in modern electronic warfare, given their heavy reliance on the number of labeled samples. To tackle these issues, a feature fusion-based land cover recognition approach is proposed, which introduces Convolutional Embedding Sequence Encoder (CE-SE) to capture the complex clutter characteristics of HRRP, achieving land cover recognition with a small number of labeled HRRP samples and eliminating the reliance on two-dimensional image data. Experimental results validated on Mini-SAR data from unmanned aerial vehicles demonstrate effective land cover recognition using HRRP. This method significantly improves the recognition accuracy for five land cover types, exceeding 92%, even with only half the sample size compared to traditional deep learning methods. Additionally, the model's inference time for a single HRRP sample is just 1.3 milliseconds, demonstrating its capability for real-time land cover recognition.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 3","pages":"1-24"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper introduces a Fractal Patch Antenna (FPA) integrated with Photonic Crystals (PhC) designed for Intelligent Transportation Systems (ITS) in the Millimeter-wave bands (mmWaves) given the importance of the application of mmWaves in Vehicle-to-Everything (V2X) networks, we assumed, as examples, that the antenna is designed to resonate at three frequency bands: 31.42 GHz, 37.76 GHz, and 38.92 GHz. With a gain of 10.88 dBi, at 38.92 GHz, the antenna demonstrates promising signal reception and transmission capabilities, which are anticipated to be important for ITS operations. The antenna bandwidth covers multiple frequency bands, enabling versatile communication in mmWaves V2X applications. To evaluate the performance of the antenna, we conducted a detailed analysis of its configuration. This included a comparison of the antenna with and without the PhC integration, as well as an exploration of rectangular lattice structure. In addition, variations in hole sizes and spacing were examined to assess their impact on key parameters such as the gain and reflection coefficient. The integration of fractal geometry and PhC structures results in a compact, high-performance antenna suitable for mmWave communication. The integration of fractal geometry and PhC structure results in compactness and high performance in mmWaves communication applications. Through simulation and analysis, including radiation pattern, gain, and reflection coefficient plot assessment, the antenna performance is thoroughly evaluated. The study highlights the potential of the proposed FPA-PhC antenna configuration to enhance communication networks within the ITS, significantly advancing the ITS system with support from the mmWave bands.
{"title":"Fractal patch antenna based on photonic crystal for enhanced millimeter-wave communication in intelligent transportation systems","authors":"Nila Bagheri;Jon M. Peha;Fernando J. Velez","doi":"10.1029/2024RS008072","DOIUrl":"https://doi.org/10.1029/2024RS008072","url":null,"abstract":"This paper introduces a Fractal Patch Antenna (FPA) integrated with Photonic Crystals (PhC) designed for Intelligent Transportation Systems (ITS) in the Millimeter-wave bands (mmWaves) given the importance of the application of mmWaves in Vehicle-to-Everything (V2X) networks, we assumed, as examples, that the antenna is designed to resonate at three frequency bands: 31.42 GHz, 37.76 GHz, and 38.92 GHz. With a gain of 10.88 dBi, at 38.92 GHz, the antenna demonstrates promising signal reception and transmission capabilities, which are anticipated to be important for ITS operations. The antenna bandwidth covers multiple frequency bands, enabling versatile communication in mmWaves V2X applications. To evaluate the performance of the antenna, we conducted a detailed analysis of its configuration. This included a comparison of the antenna with and without the PhC integration, as well as an exploration of rectangular lattice structure. In addition, variations in hole sizes and spacing were examined to assess their impact on key parameters such as the gain and reflection coefficient. The integration of fractal geometry and PhC structures results in a compact, high-performance antenna suitable for mmWave communication. The integration of fractal geometry and PhC structure results in compactness and high performance in mmWaves communication applications. Through simulation and analysis, including radiation pattern, gain, and reflection coefficient plot assessment, the antenna performance is thoroughly evaluated. The study highlights the potential of the proposed FPA-PhC antenna configuration to enhance communication networks within the ITS, significantly advancing the ITS system with support from the mmWave bands.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 5","pages":"1-18"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. A. Nosikov;M. V. Klimenko;A. M. Padokhin;V. V. Nosikova;P. F. Bessarab
The generalized force method, previously developed for an isotropic inhomogeneous ionosphere, exploits the knowledge about the character of the extrema of the phase distance—where high ionospheric rays correspond to minima and low rays to saddle points—to systematically find all relevant rays between fixed points, thereby enabling efficient global point-to-point ray tracing. In this article, the generalized force approach is extended to magneto-active, anisotropic ionosphere by locating minima and saddle points of a more general phase distance functional where trial functions include both the candidate ray path geometry and the orientation of the wavefront. For both O and X modes, the rays are found using an optimization algorithm guided by the generalized force whose definition depends on the ray type. The generalized force method, implemented in the form of computer software, is applied to problems of oblique sounding in realistic ionosphere described by NeQuick2 and IGRF13 models. The results of the ionogram simulations demonstrate the method's ability to solve routine problems of ionospheric ray tracing and show its potential in solving various inverse problems, as well as in verifying and correcting models of the ionosphere.
{"title":"Generalized force method for point-to-point ray tracing in anisotropic ionosphere: Implementation and applications to NeQuick2 and IGRF13 models","authors":"I. A. Nosikov;M. V. Klimenko;A. M. Padokhin;V. V. Nosikova;P. F. Bessarab","doi":"10.1029/2024RS008092","DOIUrl":"https://doi.org/10.1029/2024RS008092","url":null,"abstract":"The generalized force method, previously developed for an isotropic inhomogeneous ionosphere, exploits the knowledge about the character of the extrema of the phase distance—where high ionospheric rays correspond to minima and low rays to saddle points—to systematically find all relevant rays between fixed points, thereby enabling efficient global point-to-point ray tracing. In this article, the generalized force approach is extended to magneto-active, anisotropic ionosphere by locating minima and saddle points of a more general phase distance functional where trial functions include both the candidate ray path geometry and the orientation of the wavefront. For both O and X modes, the rays are found using an optimization algorithm guided by the generalized force whose definition depends on the ray type. The generalized force method, implemented in the form of computer software, is applied to problems of oblique sounding in realistic ionosphere described by NeQuick2 and IGRF13 models. The results of the ionogram simulations demonstrate the method's ability to solve routine problems of ionospheric ray tracing and show its potential in solving various inverse problems, as well as in verifying and correcting models of the ionosphere.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 3","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiajing Chen;Mingran Sun;Lu Bai;Xiang Cheng;Xuesong Cai
Vehicle-to-Vehicle (V2V) communications have received a lot of attention as it can significantly improve efficiency and safety of road traffic. This paper introduces a novel data set, constructed at urban crossroads in different vehicular traffic densities (VTDs) for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, utilizing Ray-tracing techniques for its development. Channel modeling was performed for the path loss, shadowing, and multipath characteristics of the propagation channel, that is, the root-mean-square delay spread, azimuth of arrival (AoA) spread and elevation of arrival (EoA) spread, correlations of spreads, and coherent distances of spreads of interest. The simulation results indicate that scenarios with low and medium VTD exhibit lower path loss and delay spread values compared to scenarios with high VTD. The AoA spread is significantly larger in the LOS scenarios compared to the NLOS scenarios, and the EoA spread demonstrates greater variations with different VTDs in both the LOS and the NLOS conditions. These results are important for generating realistic channel realizations for the design and performance evaluation of V2V communication algorithms in the context of the sixth-generation (6G) wireless networks.
{"title":"Simulation-based channel modeling at 28 GHz for different vehicular traffic densities in vehicle-to-vehicle scenarios","authors":"Jiajing Chen;Mingran Sun;Lu Bai;Xiang Cheng;Xuesong Cai","doi":"10.1029/2024RS008155","DOIUrl":"https://doi.org/10.1029/2024RS008155","url":null,"abstract":"Vehicle-to-Vehicle (V2V) communications have received a lot of attention as it can significantly improve efficiency and safety of road traffic. This paper introduces a novel data set, constructed at urban crossroads in different vehicular traffic densities (VTDs) for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, utilizing Ray-tracing techniques for its development. Channel modeling was performed for the path loss, shadowing, and multipath characteristics of the propagation channel, that is, the root-mean-square delay spread, azimuth of arrival (AoA) spread and elevation of arrival (EoA) spread, correlations of spreads, and coherent distances of spreads of interest. The simulation results indicate that scenarios with low and medium VTD exhibit lower path loss and delay spread values compared to scenarios with high VTD. The AoA spread is significantly larger in the LOS scenarios compared to the NLOS scenarios, and the EoA spread demonstrates greater variations with different VTDs in both the LOS and the NLOS conditions. These results are important for generating realistic channel realizations for the design and performance evaluation of V2V communication algorithms in the context of the sixth-generation (6G) wireless networks.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 5","pages":"1-10"},"PeriodicalIF":1.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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