Radio Spectrum Research Articles

Subchannel assignment for social-assisted UAV cellular networks using dynamic hypergraph coloring

Device-to-Device (D2D) communication when used in conjugation with Unmanned Aerial Vehicle (UAV) Femtocell and unlicensed spectrum can effectively tackle the ever-increasing mobile data demands. However, D2D communication raises security and privacy concerns among users due to the absence of a centralized entity such as a base station. Therefore, exploring social connections among users becomes imperative to enable secure and trustworthy D2D communication. This paper seeks to improve the performance of a social-assisted UAV cellular network augmented by D2D communication by proposing a novel subchannel assignment technique employing hypergraph coloring. Considering the real-world scenario, we incorporate the user/UAV mobility by using dynamic hypergraph coloring for subchannel assignment instead of the static one. Our proposed technique shifts a set of cellular users from the licensed to the unlicensed band based on their social connection with other co-channel D2D users. Additionally, we assign subchannels to different users to optimize the throughput while minimizing overall interference. Our proposed technique demonstrates significant improvements in system throughput, energy efficiency, and interference efficiency compared to conventional techniques. For our proposed technique, we observed improvements of 69%, 42%, and 15% in the per user system throughput when compared with the conventional techniques (graph, hypergraph, and dynamic-hypergraph, respectively). Moreover, our technique achieves higher per user energy efficiency by 120%, 70%, and 25%, and higher per user interference efficiency by 92%, 43%, and 22%, respectively, compared to graph, hypergraph, and dynamic-hypergraph techniques.

Energetic particle activity in AD Leo: Detection of a solar-like type-IV burst

Context. AD Leo is a young and active M dwarf with high flaring rates across the X-ray-to-radio bands. Flares accelerate particles in the outer coronal layers and often impact exo-space weather. Wide-band radio dynamic spectra let us explore the evolution of particle acceleration activity across the corona. Identifying the emission features and modelling the mechanisms can provide insights into the possible physical scenarios driving the particle acceleration processes. Aims. We performed an 8 h monitoring of AD Leo across the 550-850 MHz band using upgraded-Giant Metrewave Radio Telescope (uGMRT). The possible flare and post-flare emission mechanisms are explored based on the evolution of flux density and polarisation. Methods. The python-based module, Visibility Averaged Dynamic spectrum (VISAD), was developed to obtain the visibility-averaged wide-band dynamic spectra. Direct imaging was also performed with different frequency-time averaging. Based on existing observational results on AD Leo and on solar active region models, radial profiles of electron density and magnetic fields were derived. Applying these models, we explored the possible emission mechanisms and magnetic field profile of the flaring active region. Results. The star displayed a high brightness temperature (TB≈ 1010−1011 K) throughout the observation. The emission was also nearly 100% left circularly polarised during bursts. The post-flare phase was characterised by a highly polarised (60–80%) solar-like type IV burst confined above 700 MHz. Conclusions. The flare emission favours a Z-mode or a higher harmonic X-mode electron cyclotron maser emission mechanism. The >700 MHz post-flare activity is consistent with a type-IV radio burst from flare-accelerated particles trapped in magnetic loops, which could be a coronal mass ejection (CME) signature. This is the first solar-like type-IV burst reported on a young active M dwarf belonging to a different age-related activity population (‘C’ branch) compared to the Sun (‘I’ branch). We also find that a multipole expansion model of the active region magnetic field better accounts for the observed radio emission than a solar-like active region profile.

Enhancing spectrum sensing efficiency in multi‐channel cognitive device‐to‐device networks: Medium Access Control layer strategies and analysis

AbstractThe detection and characterisation of electromagnetic signals within a specific frequency range, known as spectrum sensing, plays a crucial role in Cognitive Radio Networks (CRNs). The CRNs aim to adapt their communication parameters to the surrounding radio environment, thereby improving the efficiency and utilisation of the available radio spectrum. Spectrum sensing is particularly important in device‐to‐device (D2D) communication when operating independently of the cellular network infrastructure. The Medium Access Control (MAC) protocol coordinates device communication and ensures interference‐free operation of the CRN coexisting with the primary cellular network. A spectrum sensing strategy at the MAC layer for cognitive D2D communication. The strategy focuses on reducing the overall sensing period allocated at the MAC layer by having each Cognitive D2D User (cD2DU) sense a smaller subset of available channels while maintaining the same sensing time for cellular user detection at the physical layer. To achieve this, the concept of concurrent groups of D2D devices is introduced in proximity, which are formed by using unique IDs of cD2DUs during the device discovery stage. Each concurrent group senses a specific portion of the cellular user band in a shorter time, resulting in a reduced overall sensing period. In addition to mitigating traffic congestion through data diversion from the cellular network, the proposed strategy facilitates the concurrent sensing of multiple channels by cD2DUs within the underutilised cellular user band. This leads to extended data transmission periods, increased network throughput, and effective offloading of the cellular network. The effectiveness of the proposed work is evaluated by considering factors, such as network throughput and transmission time. Simulation results confirm the effectiveness of the approach in improving spectrum utilisation and communication efficiency in multi‐channel Cognitive D2D Networks (cD2DNs).

Adaptive Federated Learning for Automatic Modulation Classification Under Class and Noise Imbalance

The ability to rapidly understand and label the radio spectrum in an autonomous way is key for monitoring spectrum interference, spectrum utilization efficiency, protecting passive users, monitoring and enforcing compliance with regulations, detecting faulty radios, dynamic spectrum access, opportunistic mesh networking, and numerous NextG regulatory and defense applications. We consider the problem of automatic modulation classification (AMC) by a distributed network of wireless sensors that monitor the spectrum for signal transmissions of interest over a large deployment area. Each sensor receives signals under a specific channel condition depending on its location and trains an individual model of a deep neural network (DNN) accordingly to classify signals. To improve modulation classification accuracy, we consider federated learning (FL) where each individual sensor shares its trained model with a centralized controller, which, after aggregation, initializes its model for the next round of training. Without exchanging any spectrum data (such as in cooperative spectrum sensing), this process is repeated over time. A common DNN is built across the net- work while preserving the privacy associated with signals collected at different locations. Given their distributed nature, the statistics of the data across these sensors are likely to differ significantly. We propose the use of adaptive federated learning for AMC. Specifically, we use FEDADAM -an algorithm using Adam for server optimization – and ex- amine how it compares to the FEDAVG algorithm -one of the standard FL algorithms, which averages client parameters after some local iterations, in particular in challenging scenarios that include class imbalance and/or noise-level imbalance across the network. Our extensive numerical studies over 11 standard modulation classes corroborate the merit of adaptive FL, outperforming its standard alternatives in various challenging cases and for various network sizes.

A Compact GaN Power Amplifier Module for New Generation Cellular Basestations

This paper presents a compact class-AB Power Amplifier Module (PAM) designed for new generation massive Multiple Input Multiple Output (MiMo) cellular base stations. The module is designed at the center frequency of 3.5GHz targeting Long Term Evolution (LTE) and 5G New Radio (NR) bands. The module is a hybrid design that incorporates a Gallium Nitride (GaN) High Mobility-Electron Transistor (HEMT) die, discrete components-based input, and output matching networks. The entire design is realized on an 8.5 x 5.2 mm, 2-layer Rogers4003C substrate. The module is assembled on a PCB as an open-top for post-characterization tuning. The small signal and large signal measurements are in quite good agreement. The measurement results show that the amplifier is unconditionally stable, the input return loss is 12.2 dB, the output return loss is 7.7 dB, and the small signal gain is 13.4 dB. The saturated output power is 33.3 dBm with a Power Added Efficiency of 20.1%. The small signal gain drops to 11.2 dB at around 22 dBm of input power due to GaN technology’s intrinsic soft compression characteristics.

Interacting supernovae as high-energy multimessenger transients

Multiwavelength observations have revealed that dense, confined circumstellar material (CCSM) commonly exists in the vicinity of supernova (SN) progenitors, suggesting enhanced mass losses years to centuries before their core collapse. Interacting SNe, which are powered or aided by interaction with the CCSM, are considered to be promising high-energy multimessenger transient sources. We present detailed results of broadband electromagnetic emission, following the time-dependent model proposed in the previous work on high-energy SN neutrinos [K. Murase, New prospects for detecting high-energy neutrinos from nearby supernovae, ]. We investigate electromagnetic cascades in the presence of Coulomb losses, including inverse-Compton and synchrotron components that significantly contribute to MeV and high-frequency radio bands, respectively. We also discuss the application to SN 2023ixf. Published by the American Physical Society 2024

A self-regulated stochastic acceleration model of pulsar wind nebulae

Abstract Pulsar wind nebulae (PWNe) are clouds of the magnetized relativistic electron/positron plasma supplied from the central pulsar. However, the number of radio-emitting particles inside a PWN is larger than the expectation from the study of pulsar magnetospheres and then their origin is still unclear. A stochastic acceleration of externally injected particles by a turbulence inside the PWN is proposed by our previous studies. In this paper, the previous stochastic acceleration model of the PWN broadband spectra is improved by taking into account the time evolution of the turbulent energy and then the total energy balance inside a PWN is maintained. The turbulent energy supplied from the central pulsar is wasted by the backreaction from the stochastic particle acceleration and the adiabatic cooling according the PWN expansion. The model is applied to the Crab Nebula and reproduce the current broadband emission spectrum, especially the flat radio spectrum although time evolution of the turbulent energy (diffusion coefficient) is a bit complicated compared with our previous studies, where we assumed an exponential behavior of the diffusion coefficient.

An arcsecond view at 1–2 GHz into the Galactic Bulge

ABSTRACT We present the results of a high angular resolution (1.1 arcsec) and sensitivity (maximum of ∼0.1 mJy) radio survey at 1–2 GHz in the Galactic Bulge. This complements the X-ray Chandra Galactic Bulge Survey, and investigates the full radio source population in this dense Galactic region. Radio counterparts to sources at other wavelengths can aid in classification, as there are relatively few types of objects that are reasonably detectable in radio at kiloparsec distances, and even fewer that are detected in both X-rays and radio. This survey covers about 3 sq deg of the Galactic Bulge Survey area (spanning the Galactic coordinate range of −3° < l < +3° and +1.6° < b < +2.1°) as a first look into this region of the Galaxy with this combination of frequency, resolution, and sensitivity. Spectral indices within the observed band of 1–2 GHz were calculated for each source to assist in determining its emission mechanism. We find 1617 unique sources in the survey, 25 of which are radio counterparts to X-ray sources, and about 100 of which are steep-spectrum (α ≲ −1.4) point sources that are viable pulsar candidates. Four radio sources are of particular interest: a compact binary; an infrared transient with an inverted radio spectrum; a potential transitional millisecond pulsar candidate; and a very steep spectrum radio source with an X-ray and bright infrared counterpart. We discuss other notable sources, including possible radio transients, potential new planetary nebulae, and active galactic nuclei.

ED-SS based Cognitive Radio (CR) over Various Fading Channels for Modern Wireless Communications

Cognitive Radio (CR) has already been proved to provide the better solution for the problem of spectrum insufficiency in which every wireless system occupies the limited bandwidth spectrum (LBS) allotting to the licensed users. Sometimes, this LBS is empty in a certain place at a certain time that is called as spectrum holes estimated by spectrum sensing (SS). The spectrum sensing is the main technique used in cognitive radio and various spectrum sensing techniques are available in the literature such as: energy detection (ED), matched filter detection (MFD) and cyclo-stationary feature detection (CFD). In the present work, energy detection-spectrum sensing (ED-SS) based cognitive radio system has been implemented which can analyze the energy of the spectrum. The various fading channels such as additive white gaussian noise (AWGN), Rayleigh, and Nakagami have been incorporated in the present work over which the performance of cognitive radio has been analyzed and compared using the ED-SS technique. The experimental results show thatt the detection of the presence of primary user signal using proposed ED-SS technique is easier with low computational complexities in Cognitive Radio (CR) networks. The present work also demonstrates when the performance of proposed ED-SS technique over aforesaid three fading channels are compared, Nakagami-m fading channels exhibits superior improvement in Pd compared to Rayleigh and AWGN fading channels

The relationship between the turnover frequency and photo-ionization in radio sources

ABSTRACT We investigate the connection between the turnover frequency in the radio spectrum, νTO, and the rate of ionizing ultraviolet photons, $Q_{\rm {H{\small I}}}$, in extragalactic sources. From a large, optically selected sample, we find νTO to be correlated with $Q_{\rm {H\,{\small I}}}$ in sources that exhibit a turnover. The significance of the correlation decreases when we include power-law radio sources as limits, by assuming that the turnover frequency occurs below the lowest value observed. However, the power-law fit sources are less well sampled across the band and so these may just be contributing noise to the data. Given that the observed νTO–$Q_{\rm {H{\small I}}}$ correlation is purely empirical, we use the ionizing photon rate to obtain the electron density in a free–free absorption model. For each of the constant, exponential, constant plus exponential (Milky Way), and spherical models of the gas distribution, there is also an increase in the turnover frequency with ionizing photon rate. Furthermore, for a given gas mass, we find that the turnover frequency is anticorrelated with the scale-factor of the gas density. While other mechanisms, such as ageing electrons or synchrotron self-absorption, may be required to reproduce the spectral indices, for an exponential scale-factor similar to the linear size, this simple free–free absorption model reproduces the turnover-size correlation seen in radio sources.

Constraining the properties of Population III galaxies with multiwavelength observations

ABSTRACT The early Universe, spanning 400 000 to 400 million years after the big bang (z ≈ 1100–11), has been left largely unexplored as the light from luminous objects is too faint to be observed directly. While new experiments are pushing the redshift limit of direct observations, measurements in the low-frequency radio band promise to probe early star and black hole formation via observations of the hydrogen 21-cm line. In this work, we explore synergies between 21-cm data from the HERA and SARAS 3 experiments and observations of the unresolved radio and X-ray backgrounds using multiwavelength Bayesian analysis. We use the combined data set to constrain properties of Population II and Population III stars as well as early X-ray and radio sources. The joint fit reveals a 68 percentile disfavouring of Population III star formation efficiencies $\gtrsim 5.7~{{\ \rm per\ cent}}$. We also show how the 21-cm and the X-ray background data synergistically constrain opposite ends of the X-ray efficiency prior distribution to produce a peak in the 1D posterior of the X-ray luminosity per star formation rate. We find (at 68 per cent confidence) that early galaxies were likely 0.3–318 times as X-ray efficient as present-day starburst galaxies. We also show that the functional posteriors from our joint fit rule out global 21-cm signals deeper than ≲−203 mK and power spectrum amplitudes at k = 0.34 h Mpc−1 greater than $\Delta _{21}^2 \gtrsim 946\ \mathrm{mK}^2$ with 3σ confidence.

A Double-Threshold Cooperative Spectrum Sensing Algorithm in the Internet of Vehicles

To address the shortage of wireless spectrum resources caused by the rapid development of the Internet of Vehicles, spectrum sensing technology in cognitive radio is employed to tackle this issue. In pursuit of superior outcomes, a double-threshold cooperative spectrum sensing algorithm is introduced. This algorithm enhances traditional energy detection technology to mitigate the high sensitivity to noise interference in the Internet of Vehicles environment. A double-threshold judgment mechanism can be established based on the uncertainty of noise. Varying fusion rules are implemented in the collaborative spectrum sensing scheme according to the density of vehicles and the spectrum resource demand. Simulation results demonstrate that the performance of the double-threshold cooperative spectrum sensing algorithm surpasses that of the traditional single-threshold energy detection scheme, particularly evident under lower Signal-to-Noise Ratio (SNR) conditions. Moreover, the proposed algorithm exhibits superior sensing performance in environments characterized by higher noise uncertainty.

Distributed DQN-based network-wide energy efficiency maximization for 5G NR-U and Wi-Fi coexistence environments

To effectively manage the escalating traffic, attention is drawn to the coexistence mechanism of cellular and Wi-Fi networks which offload the cellular traffic from the licensed band to the unlicensed band. For the coexistence of 5G new radio-unlicensed and Wi-Fi, we tackle the energy efficiency maximization problem by sequentially determining the duty cycle and transmit power through the use of distributed deep Q-network (DQN) techniques. When utilizing the existing unlicensed band, the proposed method minimizes the impact on Wi-Fi networks while achieving optimal energy efficiency. Simulations validate the superior energy efficiency of the proposed coexistence mechanism over various benchmark methods.

Abell 0399–Abell 0401 radio bridge spectral index: First multi-frequency detection

Aims. Recent low-frequency radio observations at 140 MHz discovered a bridge of diffuse emission with a length of 3 Mpc that connects the galaxy clusters Abell 0399 and Abell 0401. We present follow-up observations at 60 MHz to constrain the spectral index of the bridge, which has only been detected at 140 and 144 MHz so far. Methods. We analysed deep (∼18 h) LOw Frequency ARray (LOFAR) Low Band Antenna (LBA) data at 60 MHz to detect the bridge at very low frequencies. We then conducted a multi-frequency study with LOFAR HBA data at 144 MHz and uGMRT data at 400 MHz. Assuming second-order Fermi mechanisms for the re-acceleration of relativistic electrons driven by turbulence in the radio bridge regions, we compared the observed radio spectrum with theoretical synchrotron models. Results. The bridge is detected in the 75″ resolution LOFAR image at 60 MHz, and its emission fully connects the region between the two galaxy clusters. Between 60 MHz and 144 MHz, we found an integrated spectral index value of α60144 = −1.44 ± 0.16 for the bridge emission. For the first time, we produced spectral index and related uncertainties maps for a radio bridge. We produce a radio spectrum that shows a significant steepening between 144 and 400 MHz. Conclusions. This detection at low frequencies provides important information for models of particle acceleration and magnetic field structure on very extended scales. The spectral index gives important clues about the origin of inter-cluster diffuse emission. The steepening of the spectrum above 144 MHz can be explained in a turbulent re-acceleration framework, assuming that the acceleration timescales are longer than ∼200 Myr.

Insights into the broadband emission of the TeV blazar Mrk 501 during the first X-ray polarization measurements

Aims. We present the first multiwavelength study of Mrk 501 that contains simultaneous very-high-energy (VHE) γ-ray observations and X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). Methods. We used radio-to-VHE data from a multiwavelength campaign carried out between March 1, 2022, and July 19, 2022 (MJD 59639 to MJD 59779). The observations were performed by MAGIC, Fermi-LAT, NuSTAR, Swift (XRT and UVOT), and several other instruments that cover the optical and radio bands to complement the IXPE pointings. We characterized the dynamics of the broadband emission around the X-ray polarization measurements through its multiband fractional variability and correlations, and compared changes observed in the polarization degree to changes seen in the broadband emission using a multi-zone leptonic scenario. Results. During the IXPE pointings, the VHE state is close to the average behavior, with a 0.2–1 TeV flux of 20%–50% of the emission of the Crab Nebula. Additionally, it shows low variability and a hint of correlation between VHE γ-rays and X-rays. Despite the average VHE activity, an extreme X-ray behavior is measured for the first two IXPE pointings, taken in March 2022 (MJD 59646 to 59648 and MJD 59665 to 59667), with a synchrotron peak frequency > 1 keV. For the third IXPE pointing, in July 2022 (MJD 59769 to 59772), the synchrotron peak shifts toward lower energies and the optical/X-ray polarization degrees drop. All three IXPE epochs show an atypically low Compton dominance in the γ-rays. The X-ray polarization is systematically higher than at lower energies, suggesting an energy stratification of the jet. While during the IXPE epochs the polarization angles in the X-ray, optical, and radio bands align well, we find a clear discrepancy in the optical and radio polarization angles in the middle of the campaign. Such results further support the hypothesis of an energy-stratified jet. We modeled broadband spectra taken simultaneous to the IXPE pointings, assuming a compact zone that dominates in the X-rays and the VHE band, and an extended zone stretching farther downstream in the jet that dominates the emission at lower energies. NuSTAR data allow us to precisely constrain the synchrotron peak and therefore the underlying electron distribution. The change between the different states observed in the three IXPE pointings can be explained by a change in the magnetization and/or the emission region size, which directly connects the shift in the synchrotron peak to lower energies with the drop in the polarization degree.

Development of a 90–600 MHz Meter-wave Solar Radio Spectrometer

Radio observation is important for understanding coronal mass ejections (CMEs), coronal shock waves, and high-energy electron acceleration. Here, we developed a new Chashan broadband solar radio spectrometer at a meter wavelength for observing the (super)fine structure of the solar radio burst spectrum. In the signal-receiving unit, we adopt an antenna system consisting of a 12 m large-aperture parabolic reflector and dual-line polarized logarithmic periodic feed source, as well as a high-precision Sun-tracking turntable system, all of which ensure the high-precision acquisition of solar radiation signals. For the digital receiver, we use a high-speed analog-to-digital converter with a sampling rate of 1.25 GSPS to directly sample the signal amplified and filtered by the analog receiver, simplifying the structure of the analog receiver, and design a 16k-point fast Fourier transform algorithm in the field programmable gate array to perform time–frequency transformation on the sampled signals. The default frequency and temporal resolution of the system are 76.294 kHz and 0.839 ms (up to 0.21 ms), respectively. The noise coefficient of the system is less than 1 dB, the dynamic range is more than 60 dB, and the sensitivity is as high as 1 sfu. We have observed a large number of radio bursts, including type I radio storms, hundreds of type III, ∼20 type II, and ∼15 type IV bursts in the past year. These high-quality data are useful in the further study of CMEs and associated particle acceleration and the origins of solar radio bursts.

Transition to a weaker Sun: Changes in the solar atmosphere during the decay of the Modern Maximum

Context. The Sun experienced a period of unprecedented activity during the 20th century, now called the Modern Maximum (MM). The decay of the MM after its maximum in cycle 19 has changed the Sun, the heliosphere, and the planetary environments in many ways. However, studies disagree on whether this decay has proceeded synchronously in different solar parameters or not. Aims. One of the related key issues is if the relation between two long parameters of solar activity, the sunspot number and the solar 10.7 cm radio flux, has remained the same during this decay. A recent study argues that there is an inhomogeneity in the 10.7 cm radio flux in 1980, which leads to a step-like jump (“1980 jump”) in this relation. If true, this result would reduce the versatility of possible long-term studies of the Sun during the MM. Here we aim to show that the relation between sunspot number and 10.7 cm radio flux does indeed vary in time, not due to an inhomogeneous radio flux but due to physical changes in the solar atmosphere. Methods. We used radio flux measurements made in Japan at four different wavelengths, and studied their long-term relation with the sunspot number and the 10.7 cm radio flux during the decay of MM. We also used two other solar parameters, the MgII index and the number of solar active regions, in order to study the nature of the observed long-term changes in more detail. Results. We find that the 1980 jump is only the first of a series of 1–2-year “humps” that mainly occur during solar maxima. All five radio fluxes depict an increasing trend with respect to the sunspot number from the 1970s to 2010s. These results exclude the interpretation of the 1980 jump as an inhomogeneity in the 10.7 cm flux, and reestablish the 10.7 cm flux as a homogeneous measure of solar activity. The fluxes of the longer radio waves are found to increase with respect to the shorter waves, which suggests a long-term change in the solar radio spectrum. We also find that the MgII index of solar UV irradiance and the number of active regions also increased with respect to the sunspot number, further verifying the difference in the long-term evolution in chromospheric and photospheric parameters. Conclusions. Our results provide evidence for important structural changes in solar magnetic fields and the solar atmosphere during the decay of the MM, which have not been reliably documented so far. We also emphasize that the changing relation between the different (e.g., photospheric and chromospheric) solar parameters should be taken into account when using the sunspot number or any single parameter in long-term studies of solar activity.

GalaPy: A highly optimised C++/Python spectral modelling tool for galaxies

Bolstered by upcoming data from new-generation observational campaigns, we are about to enter a new era in the study of how galaxies form and evolve. The unprecedented quantity of data that will be collected from distances that have only marginally been grasped up to now will require analytical tools designed to target the specific physical peculiarities of the observed sources and handle extremely large datasets. One powerful method to investigate the complex astrophysical processes that govern the properties of galaxies is to model their observed spectral energy distributions (SEDs) at different stages of evolution and times throughout the history of the Universe. To address these challenges, we have developed GalaPy, a new library for modelling and fitting SEDs of galaxies from the X-ray to the radio band, as well as the evolution of their components and dust attenuation and reradiation. On the physical side, GalaPy incorporates both empirical and physically motivated star formation histories (SFHs), state-of-the-art single stellar population synthesis libraries, a two-component dust model for attenuation, an age-dependent energy conservation algorithm to compute dust reradiation, and additional sources of stellar continuum such as synchrotron, nebular and free-free emission, as well as X-ray radiation from low-and high-mass binary stars. On the computational side, GalaPy implements a hybrid approach that combines the high performance of compiled C++with the user-friendly flexibility of Python. Also, it exploits an object-oriented design via advanced programming techniques. GalaPy is the fastest SED-generation tool of its kind, with a peak performance of almost 1000 SEDs per second. The models are generated on the fly without relying on templates, thus minimising memory consumption. It exploits a fully Bayesian parameter space sampling, which allows for the inference of parameter posteriors and thereby facilitates the study of the correlations between the free parameters and the other physical quantities that can be derived from modelling. The application programming interface (API) and functions of GalaPy are under continuous development, with planned extensions in the near future. In this first work, we introduce the project and showcase the photometric SED fitting tools already available to users. GalaPy is available on the Python Package Index (PyPI) and comes with extensive online documentation and tutorials.

Certain aspects of the functioning of the national commission for state regulation of electronic communications, radio frequency spectrum and postal services

The paper examines the administrative and legal basis of the functioning of the National Commission, which carries out state regulation in the spheres of electronic communications, radio frequency spectrum and postal communications in Ukraine. The main tasks, functions and powers of the National Commission are summarized, the main purpose of its creation and functioning is indicated - it is the regulation of the communication industries, the electromagnetic spectrum and the postal industry in Ukraine. It was determined that the National Commission aims to ensure equal conditions for all participants of these markets. The regulatory framework regulating the Commission's activities, including regulatory acts, was analyzed. Problems related to the procedure for appointing the chairman and members of the commission, which may affect their independence and effectiveness of regulation by the regulatory and legal framework, are highlighted. Important aspects of providing anti-crisis management and protection of electronic communication infrastructure in the conditions of military conflict are outlined and highlighted. In the work of the National Commission, inconsistencies and contradictions in the legislative framework regulating the Commission's activities were identified and the need to improve the administrative and legal framework was emphasized to ensure the effective functioning of the body in the context of modern challenges and integration with the European Union, also military risks should be taken into account, which should be reflected in the normative legal acts regulating the activity of the commission, in particular, the use of the radio frequency spectrum should take into account not only the economic component, competitiveness and impartiality, but also the responsibility for the security of the state.

EVALUATING THE IMPACT OF CROSS-CORRELATION PROPERTIES OF COMPLEX SIGNALS ON THE CHARACTERISTICS OF SMART RADIO SYSTEMS

The article discusses modern problems and prospects for the development of "smart radio" systems using complex signals for effective use of the radio frequency spectrum. Cognitive radio systems use complex signals to efficiently use the radio frequency spectrum. It is emphasized that the ensemble size of complex signals is a key factor that affects various system characteristics such as immunity, data transmission efficiency, and spectral efficiency. Various methods can be used to increase the ensemble size of complex signals, including the use of pseudo-random sequences with low levels of sidelobes in the cross-correlation function, new complex signal generation algorithms (e.g., based on artificial intelligence), and new coding techniques that allow for increased ensemble size. without compromising data transmission efficiency. The choice of a specific approach to increasing the size of the ensemble of complex signals depends on the specific requirements of the cognitive telecommunication system. An important task is the development of new methods of generating complex signals with high interference-resistant properties, which allow to increase the size of the ensemble without compromising the quality of service. This task is important for the development of next-generation "smart radio" systems. The analysis of various methods of increasing the size of the ensemble of complex signals is presented. The maximum correlation immunity is calculated for different lengths of sequences and the results of research for five sequences are given: pseudorandom noise, nonlinear sequence, Galois sequence, Gold sequence and Kiyosaki sequence. This information can be used to select the optimal sequence taking into account the specific requirements of "smart radio" systems. The conclusions of the article can make a valuable contribution to the development of effective and productive telecommunication systems for future generations of "smart radio".