5G Signals Research Articles

Electromagnetic exposure analysis of the subway passenger under the civil communication system radiation.

In order to assess the electromagnetic exposure safety of passengers under the civil communication system of the subway, the radio-frequency (RF) electromagnetic environment of subway carriage is established by using COMSOL Multiphysics software, it includes a 1-1/4 " leaky coaxial cable (LCX1) and a 1-5/8" leaky coaxial cable (LCX2), which are designed to be the exposure sources, and twelve passengers at different position. The electromagnetic environment model has been verified through field measurement. The exposure dose distribution of twelve passengers is compared and analyzed, when LCX1 and LCX2 works respectively. The simulated results show that, to compare with LCX2, the electromagnetic dose absorbed by the passengers is reduced by 9.19% and 22.50% at 2100 MHz and 2600 MHz respectively. The specific absorption rate (SAR) of passengers obtains the maximum value of 1.91×10-4 W/Kg and the temperature rise to 0.214 K when the LCX1 works at 3400 MHz. By comparing with the public exposure limitation of the International Commission of Non-Ionizing Radiation Protection (ICNIRP), it demonstrates the electromagnetic exposure safety of the passengers under the civil communication system. More importantly, the proposed LCX1 not only could add the 5G signal cover but also lower the SAR absorbed by the passengers, which indicates that the public electromagnetic exposure dose could be reduced by adjusting the radiation performances of exposure source, which provide a new way for electromagnetic protecting.

Polarization Insensitive and Thin Metamaterial Absorber Performed in High-Frequency 5G Bands

A variety of fascinating applications, including 5G communication devices, high-speed data transfer, and large-scale Internet of Things (IoT), make life easier with 5G technology. Despite the 5G’s superior features, the percentage of electromagnetic (EM) waves in the environment execute a significant increase, unpleasantly. Broadband metamaterial absorbers are an appealing alternative to gather these unwanted signals. This study aims to numerically investigate a broadband metamaterial absorber (MMA) in the 5G high-frequency spectral range with the metasurface formed with coupled resistors. In addition, the 24.25-27.5GHz frequency range, one of the high-frequency 5G bands used by selected countries such as the European Union and China, was preferred. The minor aim of this study is that the usage of coupled elements as resistors may have the ability to increase the absorption bandwidth and magnitude. Comprehensive simulations were performed using the finite integration technique (FIT) utilized by the CST Microwave Studio program to investigate the absorber performance and other relevant parameters. The unit cell design is created metal-substrate-metal structures as asymmetric, single-layer, and easy to implement. The absorption responses are investigated according to the oblique incidence angle, polarization angle for TE &TM modes. The suggested MMA provided an absorbency response above 87.6% in the frequency range 24.20-27.30GHz under normal incidence. Moreover, to comprehend the physical mechanism on absorption, the top and bottom surfaces of the absorber's electric field and surface current distributions are assessed. The designed MMA resulting in relatively high performance and polarization insensitive is helpful for electromagnetic interference (EMI) shielding of 5G signals in the FR2/mmWave frequency regime.

Feasibility Study of Using 5G Signals for Illumination Purposes in Passive Radar

Feasibility Study of Using 5G Signals for Illumination Purposes in Passive Radar

The effects of 5G network on people and the environment: A machine learning approach to the comprehensive analysis

The progression of telecommunications, starting from the inception of 1G networks in 1979 to the advent of 5G technology in 2019, represents a significant journey of advancement for humanity. As we approach the era of 5G, characterized by heightened machine-to-machine connectivity and transformative applications in AI, IoT, and cloud computing, it becomes imperative to acknowledge and address concerns regarding its potential impacts on health and the environment. Utilizing machine learning algorithms, particularly implemented in Python for this research, provides a potent approach to analyzing intricate datasets concerning 5G signals and their potential correlations with healthcare outcomes. After carefully cleaning and preparing the data and conducting linear regression analysis, uncovered evidence backing the notion that 5G antennas emit greater levels of radiation compared to 4G antennas emerged - a fact often concealed by corporations. Despite relying on a restricted dataset, the results emphasize the necessity for more accurate data to improve model precision. Ongoing research endeavors are vital to alleviate public anxieties regarding 5G technology, thereby fostering trust and bolstering awareness on a wider front.

Multi-tier dynamic sampling weak RF signal estimation theory

This paper presents a theoretical analysis in discrete time for a multi-tier weak radiofrequency (RF) signal estimation process with N simultaneous signals. Discrete time dynamic sampling is introduced and is shown to provide the capability to extract signal parameter values with increased accuracy compared with accuracy of estimates obtained in prior work. This paper advances phase measurement approaches by proposing discrete time dynamic sampling which our paper shows offers the desirable capability for more accurate weak signal parameter estimates. For N=2 simultaneous signals with a strong signal at 850 MHz and a weak signal at 855 MHz, the results show that dynamically sampling the instantaneous frequency at 24 times the Nyquist rate provides weak signal frequency estimates that are within 1.7 times 10^{-5} of the actual weak signal frequency and weak signal amplitude estimates that are within 428 PPM of the actual weak signal amplitude. Results are also presented for situations with N=2 simultaneous 5G signals. In one case, the strong signal is 3950 MHz, and the weak signal is 3955 MHz; in the other case the strong case is 5950 MHz, and the weak signal is 5955 MHz. The results for these cases show that estimates obtained with dynamic sampling are more accurate than estimates provided using a single sample rate of 65 MSPS. This work has promising applications for weak signal parameters estimation using instantaneous frequency measurements.

Indoor positioning with multi-beam CSI of commercial 5G signals

The fifth-generation (5G) network has been deployed for a vast number of users. The advanced capabilities of 5G technology have opened up opportunities for accuracy positioning and navigation. However, when it comes to indoor positioning using commercial 5G signals, there are persistent challenges. One particular challenge arises from the fact that in numerous indoor scenarios, there is only one base station (called gNB) heard from the receiver. This limitation makes the traditional geometric methods difficult to be applied indoors for 5G positioning. To solve the problem of indoor positioning with single 5G gNB, we propose a fingerprinting method based on the multi-beam of 5G downlink signals. This method utilizes the multi-beam Channel State Information (CSI) and employs an Extreme Learning Machine (ELM) for dimensionality reduction, aiming to improve both the accuracy and efficiency of indoor positioning. To assess the effectiveness of this method, field tests were conducted in indoor scenarios. The results demonstrate that, by taking the advantages of multi-beam property in 5G signals, it is able to achieve CSI positioning in single-gNB scenario, and the positioning accuracy over 94% while improving the positioning efficiency.

Analysis of 5G and LTE Signals for Opportunistic Navigation and Time Holdover.

The purpose of this study was to evaluate the stability and therefore suitability of available fifth generation (5G) and long-term evolution (LTE) signals for positioning navigation and timing (PNT) purposes with particular focus on answering questions around the time-scale-dependent stability of these sources, which, to our knowledge, has not been addressed in the context of the numerous publications within the PNT community to date. The methodology used directly measured the over-the-air signal phase stability to one or more of the cellular signal sources that were visible from the lab environment simultaneously while using a local atomic clock or differential measurements to isolate the time stability of the observable cellular downlink signals. This approach was taken since it does not require subscription or association with the networks under test. Instead, it exploits a 'signal of opportunity' (SoP) approach to signal use for PNT purposes. The somewhat surprising result is that the time domain instability of the sources was highly variable, dependent on the implementation choices of the operator, and that the stability of even the modernized towers was generally best at interrogation intervals of approximately 0.01 s, which indicates that the existing exploitation of these signals within the PNT community has substantial room for improvement through simple changes to the selected update rate used.

Analyzing Troubleshooting of BTS Transmit Power and 4G LTE Coverage Area via VSWR Value Measurement

The Voltage Standing Wave Ratio (VSWR) serves as a comparative measure between transmitter and receiver voltages, impacting site transmit power. VSWR values at a Radio Base Station (RBS) are evident in feeder cable losses, jumpers, combiners, and radio antenna losses. This study aims to assess the impact of poor VSWR values on BTS transmit power and perform troubleshooting analysis on 4G signal quality and Coverage Area. The study commenced with a literature review and VSWR measurements in the Gurun Laweh Aia Pacah region. The process involved identifying VSWR issues at the BTS site, conducting a Drive Test using pocket Tems, and troubleshooting the VSWR problem. Drive Test findings encompassed areas with weak signals, BTS site data, and problematic spots. The analysis utilized applications like Tems Discovery and MapInfo Pro. Results along the Gurun Laweh Aia Pacah road showed signal strength affected by a high VSWR value of 1.6. RSRP data rated 50% in the good category, SINR at 31% in the good category, and throughput at 5% in the good category. Elevated VSWR values diminish signal range, subsequently impacting traffic metrics. Immediate VSWR troubleshooting becomes imperative; low VSWR promotes higher transmit power efficiency, while normal VSWR ensures optimal transmit power efficiency.

Evaluation of mitochondrial stress following ultraviolet radiation and 5G radiofrequency field exposure in human skin cells.

Whether human cells are impacted by environmental electromagnetic fields (EMF) is still a matter of debate. With the deployment of the fifth generation (5G) of mobile communication technologies, the carrier frequency is increasing and the human skin becomes the main biological target. Here, we evaluated the impact of 5G-modulated 3.5 GHz radiofrequency (RF) EMF on mitochondrial stress in human fibroblasts and keratinocytes that were exposed for 24 h at specific absorption rateof 0.25, 1, and 4 W/kg. We assessed cell viability, mitochondrial reactive oxygen species(ROS) production, and membrane polarization. Knowing that human skin is the main target of environmental ultraviolet (UV), using the same read-out, we investigated whether subsequent exposure to 5G signal could alter the capacity of UV-B to damage skin cells. We found a statistically significant reduction in mitochondrial ROS concentration in fibroblasts exposed to 5G signal at 1 W/kg. On the contrary, the RF exposure slightly but statistically significantly enhanced the effects of UV-B radiation specifically in keratinocytes at 0.25 and 1 W/kg. No effect was found on mitochondrial membrane potential or apoptosis in any cell types or exposure conditions suggesting that the type and amplitude of the observed effects are very punctual.

Two-way free-space optics-based interface between fibre and 5G communication employing polarisation-orthogonal modulation

Fifth-generation (5G) communication provides a substantial increase in data transmission capacity because of more available bandwidth and advanced communication techniques. It opens the door to a range of new applications, such as 4K/8K video streaming, Internet of Things, autonomous vehicles, unmanned aerial vehicles, and more. However, atmospheric attenuation poses a technical challenge for 5G communication, especially at higher frequencies. Free-space optics (FSO)-based interface between fibre and 5G communication integrates fibre optics, FSO and 5G communications, achieving high-speed and long-distance transmission and providing an alternative for 5G signal transport. Here we report a two-way fibre-FSO-5G wireless communication employing polarisation-orthogonal modulation. After 25-km single-mode fibre, 1-km FSO, and 20-m (millimetre-wave)/10-m (sub-6 GHz) radio-frequency wireless transport, satisfactorily low bit error rates and error vector magnitudes are acquired, meeting the demands of 5G emerging applications.

A novel SIGGW dual post band-pass filter for 5G millimeter-wave band applications with a transmission zero

Integration of planar circuits been considered a credible technique for low-cost mass production of microwave and millimeter-wave circuits and systems. For the first time, in this research a dual-post band-pass filter is designed and simulated in a three-layer substrate integrated gap groove waveguide (SIGGW) for 5G millimeter-wave frequency band applications. The filter includes 12 posts (6 times 2). Also, the structure facilitates to use resonant posts and so we can design the posts to add a transmission zero in lower rejection band. The design theory algorithm and its limitations are investigated based on the circuit model of filter. The results shows that FBW of 5% and a lower band transmission zero for the proposed 12 posts filter. Also, the results are verified by simulation using CST. According to the results, the proposed filter is a good option for Ka-band applications and can be used as the building block for suppressing the LO leakage that is commonly used for up-converting the 5G signal to Ka band.

A comprehensive study on the synchronization procedure in 5G NR with 3GPP-compliant link-level simulator

The 5G New Radio synchronization procedure is the first step that the user must complete to access the mobile network. It mainly consists of the detection of the primary and secondary synchronization signals (PSS and SSS, respectively) and the decoding of the physical broadcast channel (PBCH). Our goal is to provide a comprehensive study of the synchronization procedure and investigate different techniques and approaches, through the implementation of a 5G New Radio-compliant simulator. Of significant interest is the investigation of impairments such as the fading channel, the frequency offset, and the delay spread. The results are provided in terms of detection probability for the PSS and SSS detection, and in terms of block error rate for the PBCH. From the data collected, there is evidence that choosing M-sequences for the PSS leads to an appreciably robust solution against frequency offset. The structure of the Gold sequences for SSS generation can be exploited to reduce the detection complexity, and different approaches can be chosen to improve reliability against delay spread. Moreover, the polar coding for 5G PBCH outperforms the former 4G coding technique, but they are still sensible to frequency offset. Finally, the simulator functionalities are validated through real captures of 5G signals.

In Situ Calibration of Antenna Arrays for Positioning With 5G Networks

Owing to the ubiquity of cellular communication signals, positioning with the fifth-generation (5G) signal has emerged as a promising solution in global navigation satellite system-denied areas. Unfortunately, although the widely employed antenna arrays in 5G remote radio units (RRUs) facilitate the measurement of the direction of arrival (DOA), DOA-based positioning performance is severely degraded by array errors. This article proposes an in situ calibration framework with a user terminal (UT) transmitting 5G reference signals at several known positions in the actual operating environment and the accessible RRUs estimating their array errors from these reference signals. Further, since sub-6 GHz small-cell RRUs deployed for indoor coverage generally have small-aperture antenna arrays, while 5G signals have plentiful bandwidth resources, this work segregates the multipath components via super-resolution delay estimation based on the maximum likelihood criteria. This differs significantly from existing in situ calibration works which resolve multipaths in the spatial domain. The superiority of the proposed method is first verified by numerical simulations. We then demonstrate via field test with commercial 5G equipment that, a reduction of 46.7% for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1{\text -}\sigma$</tex-math> </inline-formula> DOA estimation error can be achieved by in situ calibration using the proposed method.

Hybrid tree-and-multiple-ring radio-over-fiber transmission system for a 5G network in metropolitan areas

What we believe to be a novel radio-over-fiber (RoF) transmission system with a hybrid tree-and-multiple-ring network structure is developed and experimentally demonstrated to support broadband wireless signal transmission among the central office (CO) and densely distributed 5G base stations (BS) in urban areas. With the assistance of an advanced network structure and a unique single-line bidirectional optical add/drop multiplexer (SBOADM), the transmission system can utilize a hybrid tree-and-ring-topology fiber network to simultaneously support multiple 5G BS-Groups constructed as sub-ring-networks. Furthermore, the system manager is able to simultaneously utilize wavelength/time division multiplexing techniques to support the connected BSs and to dynamically embed extra sub-ring-networks to the main-ring-network or extra BSs to the sub-ring-network by using the RoF transmission system. Needing no backup fiber link, the transmission system enjoys intrinsic robust resilience against fiber link failures. Experimental results proved that the proposed RoF transmission system enables prompt recovery of interrupted optical fiber connection and guarantees the expected quality of service (QoS) by adjusting a few preinstalled optical switches when fiber link failure happens in the main-ring-network, in each sub-ring-network, or even in both of the above scenarios. The induced power penalty for maintaining unchanged bit error rate performance is less than 2 dB. In sum, the proposed transmission system proves to be a great network architecture suitable for supporting 5G signal transmission between the CO and BSs in an urban area due to the dynamically extensible network size and the well-protected transmission that ensures the QoS by simple operation.

Opportunities and Limitations in Radar Sensing Based on 5G Broadband Cellular Networks

In recent years, the 5G network has been deployed more and more densely. The signal coverage area is increasing, and in many countries, it allows the use of the new radio (NR) in most large cities. This makes it possible to use 5G network signals for telecommunication and remote sensing purposes. This article describes the opportunities and limitations of using 5G signals for radars. The waveform characteristics of the 5G network were tested and compared, range analyses were made, and the possibilities of detecting targets using impulse signals sent for various purposes in the network were examined. The article presents measurable properties of 5G signals that allow one to detect targets. Also, possibilities of exploiting 5G signalling for radar applications are provided. Moreover, the main limitations of using 5G waveforms and the general 5G architecture for radar purposes are discussed. Finally, a preliminary concept validation is shown with experimental results of car detection using 5G network-based passive radar.

Polarization-dependent multichannel transmission of 5G signals based on Zn0.91(Li0.5Bi0.5)0.09MoO4 low-temperature co-fired ceramics

Polarization-dependent multichannel transmission of 5G signals based on Zn0.91(Li0.5Bi0.5)0.09MoO4 low-temperature co-fired ceramics

Design and construct a Yagi Antenna with Three Reflector Element to Strengthen 4G Signal in Rural Areas

Rural areas are indicated to be still difficult to reach by 4G signals due to diverse topographical conditions and uneven landscapes, especially hilly areas that weaken the signal reception level in this region. To make the 4G signal accessible in this area, a repeater in the form of an antenna is needed to strengthen the signal. In this study, a yagi antenna is designed with three reflector elements at a working frequency of 1800 Mhz 4G LTE, expected to produce a minimum gain of 12 dBi and a more focused antenna radiation to strengthen the 4G signal in rural areas. The antenna design was simulated using CST Studio Suite software, with optimized simulation results yielding a return loss of -22 dB, VSWR 1.167, and gain 12.40 dBi. From the measurements obtained, the yagi antenna with three reflector elements works well at a frequency of 1800 Mhz, with a return loss of -34.77 dB, VSWR 1.065, gain 12.96 dBi, and unidirectional radiation. With the optimal antenna parameters and the addition of three reflector elements, it's possible to increase the gain value, even though the gain increase isn't substantial, and it narrows the HPBW (Half Power BeamWidth) value. Moreover, testing the yagi antenna at 3 different distances demonstrated that the resulting gain value can enhance 4G signal speed in rural areas

Experimental study and mechanism analysis of functional nanocrystalline cellulose to improve the electromagnetic transmission performance of ordinary Portland cement

5G signal transmission can be seriously blocked by cement-based materials, so it is very important to improve the electromagnetic transmission performance (ETP) of cement-based materials. Carboxylated nanocrystalline cellulose (NCC) is used to prepare Ordinary Portland cement paste with high ETP. The water-cement ratio and NCC content of the cement paste are 0.5 and 0–4% respectively. The test results show that the ETP of cement paste increases by 13.9%–90.6%, but the compressive strength of the sample decreases by 7.3%–87.6%. The 2% of NCC content causes the ETP of cement paste increases by 75.6%, while the compressive strength only decreases by 14.6%. The reasons for improvement of ETP are that the electrostatic force between the globule, the polymerization degree and mean chain length of C–S–H, the total volume proportion of phases (calcium hydroxide, ettringite and unhydrated cement) with low dielectric loss and the volume proportion of the no harmful pore for electromagnetic energy loss are increased, the conductivity of cement pore solution and the content of water are decreased.

An Exposimetric Electromagnetic Comparison of Mobile Phone Emissions: 5G versus 4G Signals Analyses by Means of Statistics and Convolutional Neural Networks Classification

To gain a deeper understanding of the hotly contested topic of the non-thermal biological effects of microwaves, new metrics and methodologies need to be adopted. The direction proposed in the current work, which includes peak exposure analysis and not just time-averaged analysis, aligns well with this objective. The proposed methodology is not intended to facilitate a comparison of the general characteristics between 4G and 5G mobile communication signals. Instead, its purpose is to provide a means for analyzing specific real-life exposure conditions that may vary based on multiple parameters. A differentiation based on amplitude-time features of the 4G versus 5G signals is followed, with the aim of describing the peculiarities of a user’s exposure when he runs four types of mobile applications on his mobile phone on either of the two mobile networks. To achieve the goals, we used signal and spectrum analyzers with adequate real-time analysis bandwidths and statistical descriptions provided by the amplitude probability density (APD) function, the complementary cumulative distribution function (CCDF), channel power measurements, and recorded spectrogram databases. We compared the exposimetric descriptors of emissions specific to file download, file upload, Internet video streaming, and video call usage in both 4G and 5G networks based on the specific modulation and coding schemes. The highest and lowest electric field strengths measured in the air at a 10 cm distance from the phone during emissions are indicated. The power distribution functions with the highest prevalence are highlighted and commented on. Afterwards, the capability of a convolutional neural network that belongs to the family of single-shot detectors is proven to recognize and classify the emissions with a very high degree of accuracy, enabling traceability of the dynamics of human exposure.

A High-Performance Dual-Band Switchable Bandpass Filter and Its Application in 5G Signal Detector

A High-Performance Dual-Band Switchable Bandpass Filter and Its Application in 5G Signal Detector