Broadband Wireless Research Articles

Study of Automatic Gain Control System in Broadband Radio Receiver

In modern times, almost all communication systems are digital. In the receivers of such communication systems, the analog signal is discretized and quantized using an analog-to-digital converter at an intermediate frequency. Automatic gain control is used to avoid overloading the analog-to-digital converter and to maintain intermediate frequency analog signals at a suitable fixed level. If the power of the received signals is much less than the load level of the analog-to-digital converter, the automatic gain adjustment increases the gain, reducing the quantization noise. If the received signal strength is high, the automatic gain adjustment lowers the gain so that the analog-to-digital converter is not overloaded. The accuracy of the adjustment of the transmission coefficient of the automatic adjustment of the digital amplification does not always satisfy the requirements given in real time. Based on the above, the article is devoted to the study of the digital automatic gain regulator of the broadband radio receiver.

Advances in MIMO Antenna Design for 5G: A Comprehensive Review.

Multiple-input multiple-output (MIMO) technology has emerged as a highly promising solution for wireless communication, offering an opportunity to overcome the limitations of traffic capacity in high-speed broadband wireless network access. By utilizing multiple antennas at both the transmitting and receiving ends, the MIMO system enhances the efficiency and performance of wireless communication systems. This manuscript specifies a comprehensive review of MIMO antenna design approaches for fifth generation (5G) and beyond. With an introductory glimpse of cellular generation and the frequency spectrum for 5G, profound key enabling technologies for 5G mobile communication are presented. A detailed analysis of MIMO performance parameters in terms of envelope correlation coefficient (ECC), total active reflection coefficient (TARC), mean effective gain (MEG), and isolation is presented along with the advantages of MIMO technology over conventional SISO systems. MIMO is characterized and the performance is compared based on wideband/ultra-wideband, multiband/reconfigurable, circular polarized wideband/circular polarized ultra-wideband/circular polarized multiband, and reconfigurable categories. The design approaches of MIMO antennas for various 5G bands are discussed. It is subsequently enriched with the detailed studies of wideband (WB)/ultra-wideband (UWB), multiband, and circular polarized MIMO antennas with different design techniques. A good MIMO antenna system should be well decoupled among different ports to enhance its performance, and hence isolation among different ports is a crucial factor in designing high-performance MIMO antennas. A summary of design approaches with improved isolation is presented. The manuscript summarizes the various MIMO antenna design aspects for NR FR-1 (new radio frequency range) and NR FR-2, which will benefit researchers in the field of 5G and forthcoming cellular generations.

A Novel Kernel Algorithm for Finite Impulse Response Channel Identification


 
 
 
 Over the last few years, kernel adaptive filters have gained in importance as the kernel trick started to be used in classic linear adaptive filters in order to address various regression and time-series prediction issues in nonlinear environments.In this paper, we study a recursive method for identifying finite impulse response (FIR) nonlinear systems based on binary-value observation systems. We also apply the kernel trick to the recursive projection (RP) algorithm, yielding a novel recursive algorithm based on a positive definite kernel. For purposes, our approach is compared with the recursive projection (RP) algorithm in the process of identifying the parameters of two channels, with the first of them being a frequency-selective fading channel, called a broadband radio access network (BRAN B) channel, and the other being a a theoretical frequency-selective channel, known as the Macchi channel. Monte Carlo simulation results are presented to show the performance of the proposed algorithm.
 
 
 

Experimental Optimization of the Energy Characteristics of a Ground Penetrating Radar with Continuous Linear-Frequency-Modulated Radiation

In recent years, research has been actively carried out aimed at developing the concept of construction and ways of technical implementation of ground penetrating radars with continuous wave linear-frequency-modulated (LFM) radiation. The key prerequisites for the creation of such systems are the complex consideration of the operating conditions of the radio channel in the near field, including the features associated with multichannel leakage of the probing signal components into the reception path, the presence of multipath reflections from the covering surface, the variable speed of the electromagnetic wave, and the provision of linear processing of a continuous group broadband radio signal with large dynamic range. The paper proposes and describes a scheme of a laboratory stand for LFM GPR research and optimization of the energy characteristics in modes with critical levels of reflections. The results of experiments on the analysis and optimization of the parameters of the end-to-end transfer characteristic of the radio channel are presented. Response studies were performed for two types of antennas at different suspension heights. The responses of the system to an increase in the durtion of the probing pulse and a change in the type of window function were evaluated. An empirical dependence of signal losses during propagation in radio channels of LFM GPR has been established. The conducted studies will improve the energy characteristics of ground penetrating radars with continuous LFM radiation by increasing the detection efficiency of shallow and near-surface objects.

AgRIS: wind-adaptive wideband reconfigurable intelligent surfaces for resilient wireless agricultural networks at millimeter-wave spectrum

Wireless networks in agricultural environments are unique in many ways. Recent measurements reveal that the dynamics of crop growth impact wireless propagation channels with a long-term seasonal pattern. Additionally, short-term environmental factors, such as strong wind, result in variations in channel statistics. Next-generation agricultural fields, populated by autonomous tractors, drones, and high-throughput sensing systems, require high-throughput connectivity infrastructure, resulting in the future deployment of high-frequency networks, where they have not been deployed before. More specifically, when millimeter-wave (mmWave) communication systems, a viable candidate for 5G and 6G high-throughput solutions, are deployed for higher throughput, these issues become more prominent due to the relatively small wavelength at this frequency band. To improve coverage in the mmWave spectrum in agricultural settings, reconfigurable intelligent surfaces (RISs) are a promising solution with low energy consumption and high cost efficiency when compared to half-duplex active relays with multiple antennas. To ensure link resiliency under dynamic channel behavior, an adaptive RIS for broadband wireless agricultural networks (AgRIS) at mmWave band is designed in this work. AgRIS relies on output from a time-series model that forecasts the short-term wind speed based on measured wind data, which is readily available in most farms. The temporal correlation between link reliability and wind speed is demonstrated through extensive field experiments. Our simulation results demonstrate that AgRIS with a small footprint of 11 × 11 elements can help mitigate the adversarial effects of wind-induced signal level drop by up to 8 dB and provides high energy efficiency of 1 Gbits/joule.

The complex temporal dynamics of an emerging infrastructure innovation: revisiting the ‘failure’ of the ‘successful’ innovation of Wireless Broadband (WiBro) in South Korea

ABSTRACT This paper explores the complex temporal dynamics of innovation through a longitudinal study encompassing the dramatic ‘failure’ of South Korea’s flagship WiBro (wireless broadband) technology and services to achieve widespread uptake, following their apparently ‘successful’ development and launch. WiBro emerged in Korea by enrolling diverse actors with diverging orientations around a compelling broad vision and expected national and international markets. Launched in 2006, with buoyant expectations, WiBro failed to establish critical mass in mainstream markets in the face of growing competition from rapidly evolving mobile telephone technologies. Though players committed to WiBro managed to establish some specific niche markets, the service was finally terminated in 2018. This eventual failure was rooted in a sequence of decisions as orientations shifted over the course of WiBro’s innovation. Generic and largely untested expectations were initially productive in enrolling a wide range of players in developing WiBro. However, tensions became acute as roll-out approached when the growing investments required to install a novel telecommunications infrastructure and launch WiBro services provoked more stringent assessment of specific options. As the stakes became higher, alignments shifted in a changing sociotechnical landscape; submerged differences in orientation resurfaced and commitments unravelled.

AN ENHANCED RESOURCE ALLOCATION SCHEME FOR LONG TERM EVOLUTION ADVANCED NETWORK

The emerging Long-Term Evolution Advanced (LTE-A) is an extended version of Long-Term Evolution (LTE) fourth-generation (4G) wireless broadband technologies that supports high speed transmission of multimedia applications, like video streaming, multimedia online game, Voice over IP (VoIP), browsing over the web etc. The Third Generation Partnership Project (3GPP) does not define a standard packet scheduling strategy in LTE-A. Therefore, it is expected for researchers and network service providers to design efficient schemes. This paper proposed an Enhanced Resource Allocation Scheme (E-RAS) that improves the packet scheduling strategy of LTE-A by addressing issues related to delay and fairness of users with both high and low channel conditions, for both Real Time (RT) and Non-Real Time (NRT) flows. The aim was achieved by using a fair spectrum allocation mechanism that consider the priority of RT flows of cell-centre users, without neglecting the throughput requirements of edge-centre users. Moreover, the proposed algorithm introduces an efficient traffic load balancing mechanism to efficiently regulate traffic load in LTE-A network. To evaluate the proposed scheme, simulation was conducted using the MATLAB programming with LTE-A system level simulator. The result obtained shows that the proposed scheme achieves better delay for RT and NRT traffics by 7% and 11% respectively as against the Resource Allocation Scheme to Optimize the Throughput (RASOT) scheme.

Low‐profile wideband four‐element MIMO array using Giuseppe Peano AMC surface with improved efficiency and isolation for WLAN systems

AbstractA low profile four‐element multiple‐input multiple‐output (MIMO) array of printed dipole antenna (PDA) backed by second iteration of Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for broadband wireless communications. First, a suggested PDA with a pair of microstrip E‐shaped dipoles excited by an E‐shaped microstrip feedline is used to expand the bandwidth in the range of 5.47–6.92 GHz (S11 ≤ −10 dB). Then, the suggested 4 × 4 Giuseppe Peano fractal AMC reflector is loaded into the PDA to exhibit −10 dB measured impedance bandwidth from 4.21 to 7.06 GHz (50.61%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed four‐element MIMO array loaded by 6 × 6 AMC reflector with diverse polarizations of elements introduces a low profile wideband structure. The measured results of four elements include the broad bandwidths from 4.3 to 7.05 GHz with enhanced gains (more than 8 dBi) and high efficiencies. The high isolations between the four elements with diverse polarizations are obtained larger than 26.5 dB and they reach 66 dB over the operating bandwidth for MIMO systems. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 51.33%, enhanced radiation efficiency up to 94%, and excellent impedance matching with uni‐directional radiation patterns.

3 bit terahertz coder based on a graphene composite metasurface

Terahertz (THz) frequency coders are indispensable components of broadband wireless communication systems of the future. However, the coding of THz wave at multiple frequencies is still a challenge. In this work, a 3 bit THz coder based on a graphene composite metasurface is proposed and simulated using a full-wave electromagnetic simulation software. The unit cell of the device consists of three graphene-embedded split-ring-resonators (SRRs), i.e., SRR1, SRR2, and SRR3. The device has three transmission peaks modulated by external voltages of V1, V2, and V3. The central frequency of the peak generated by SRR1 locates at 0.864 THz and its maximum modulation depth is 79.6%. The second peak generated by SRR2 locates at 1.161 THz and has a maximum modulation depth of 87%. The third peak at 1.541 THz is produced by SRR3 and has a maximum modulation depth of 85.3%. More importantly, the device can be used as a 3 bit coder, and the codes of 111, 110, 101, 011, 100, 010, 001, and 000 are successfully realized by controlling the voltages of V1, V2 and V3. The proposed device has potential applications in next-generation broadband wireless communications.

Sub-millimeter wave nanoantenna-a review

Electromagnetic waves that have a wavelength of less than one millimeter are referred to as sub millimeter waves. In sub millimeter wave-based devices and systems, antennas are critical components that are vital to their operation. Antennas are used in situations when a transition between a directed wave and a free-space wave is needed. Since, electromagnetic characteristics for receiving and transmission of the nano antenna are mutually invertible, the properties of nano antenna are analyzed in sub millimeter wave frequencies and this overcomes the limitations of conventional antenna design. They are very small in size, provide more efficiency, and do not cause health threat. This paper reviews the applications of nano antenna, which operates at sub-millimeter wave frequency, in the field of energy harvesting, space technology, IoT applications, 5G network, smart clothing, bio sensing, communication, etc? Also, the nano antenna fabricated by 3D printing technology is also reviewed. The world’s ever-increasing energy need necessitates the development of alternate energy sources. There is a lot of research and development going on right now to enhance photovoltaic systems so that they can be more efficient, but the constraint is that they can only collect energy from the visible area of the electromagnetic spectrum. As a result, a novel device known as a Nano antenna has been developed to convert heat energy taken from the infrared spectrum into electricity. In the not-too-distant future, it will have an impact on a wide range of fields, such as mobile communication (5G), radar detection, and higher order frequency applications. Space communication, broadband wireless communications, wireless optical communication, and mobile communication will also benefit from its implementation.

A Study of Mobile and Wireless Network Communication from Security Perspectives

Abstract: It has been well recorded and is widely recognized worldwide that the usage of mobile devices to perform government business has expanded over the previous 15 years. Threat actors are consequently increasingly focusing on mobile devices and the mobile infrastructure environment in order to look for opportunities for malicious exploitation that could hurt or damage the reputation of government agencies and Enterprise as well. The various protocols, standards, techniques, and systems that are available determine the security measures that are taken. An overview of security procedures, standards, and related technologies is provided. The high-capacity wired and wireless broadband network serves as the foundation for the working environment. The main study areas, current projects, and services on offer are discussed. The future information society is the focus of all endeavors. In order to help organizations create an enterprise-wide mobile security strategy and policy, this paper explains the security features of the mobile security management ecosystem like products, tools, technologies and services. We have talked about how mobile phone services are protected from dangers to information security from the standpoint of developers. Mobile Internet usage has grown, and with it, threats against mobile phones and the services they offer. On the other hand, various rapacious software or attackers are attempting to target these services.

Antena Bowtie dengan Reflektor Parabola untuk Layanan Broadband Wireless Access

Broadband Wireless Access (BWA) is useful for spreading and improving internet services evenly to all regions in Indonesia. While the frequency spectrum used in this Broadband Wireless Access (BWA) service is 2.3 GHz. The antenna gain test method is carried out with 3 antenna models working at the same frequency, and before the gain test is carried out, it is confirmed that the Voltage Standing Wave Ratio (VSWR) value ≤ 2 on the 2.3 GHz frequency spectrum. The test results of the parabolic Bowtie reflector antenna show that the gain value for each diameter is 6.35 dB, 7.3 dB, 7.45 dB, and 12.45 dB respectively. And the distance from the focus of the antenna to the reflector affects the Gain value for each reflector size. This antenna polarization is directional and the larger the diameter the higher the directivity value.

DISCRIMINATING STATISTICAL FEATURE FOR WIDEBAND SPECTRUM SENSING

Spectrum-aware devices and cognitive radios with wideband spectrum sensing will be an integral part of 5G or beyond wireless broadband. They must be fast and energy efficient for opportunistic dynamic access to the licensed spectrum. Compressed sensing (CS) methods can implement wideband sensing with reduced time and power consumption but are inaccurate at low SNR. Eigen methods are one of the best among non-CS methods but are high in computational cost. In this paper, we present a simple feature named the variance of multi-scale moving average (VMMA) that can be directly used as a decision statistic, discriminating signal from noise very accurately, even at a low signal-to-noise ratio (SNR). VMMA computes variance in a specific way over the entire band after comparing the short-term and long-term moving averages. Tests on experimental spectrum data and numerical simulations show that the proposed algorithms are not only fast but also have higher detection probability than the algorithms developed in the literature. Analytical expressions for the probability of detection and false alarm, along with the complexities of the algorithms, are also derived.

Terminal Access Method of Power Equipment Based on eSIM in WSN Environment

To ensure the integration of wireless sensor network and broadband wireless communication network, we establish a new generation of power IoTs information communication system for smart grid, and propose a distribution automation terminal solution based on eSIM card. An adaptive access algorithm based on multi logic eSIM priority, and a WSN based power acquisition system architecture, are also put forward. Then, according to the statistical analysis results of service arrival, the dialing and location information are integrated into one module. Through terminal classification and mobile modeling, a remote management mechanism based on EUICC is finally established. The system simulation test results show that the strategy adopted in this article can reduce the terminal access blocking rate in heterogeneous network environment, and the support of eSIM in WSN environment increases the integration of power equipment.

A Future Proof Reconfigurable Wireless and Fixed Converged Optical Fronthaul Network Using Silicon Photonic Switching Strategies

Broadband access services in the era of 5G and beyond are driving the evolution of optical access networks from a fiber-to-the-home/ fiber-to-the-building infrastructure to a more common access platform, compatible with both wired and wireless broadband services. Accordingly, a flexible optical access network plays a pivotal role in catering to various service requirements. This work proposes a reconfigurable converged optical fronthaul network for wireless and wired services using a 4◊4 microring resonator (MRR) based silicon photonic (SiP) switch fabric. Reconfigurable service selection is demonstrated for wavelength selective, multicast and space switching scenarios. The reconfiguration of digital data and digital radio-over-fiber (DRoF) services for cloud radio access networks (C-RAN) is demonstrated.

Automated detection and statistical study of solar radio spikes

The most typical observational features of solar radio spikes are their short duration and narrow bandwidth. We have improved the YOLOv5s network model for these characteristics by adding inclined bounding frames and attention and feature fusion mechanism modules. The decimeter- and meter-wavelength spikes observed by the Solar Broad-band Radio Spectrometer in Huairou and the Chashan Solar Radio Observatory spectrograph are used to carry out experiments, respectively. The results demonstrate that the AP value obtained by the improved network is 74%, which is almost 14% higher than the original network. The improved network detects 9709 (1379) decimeter- (meter-) wavelength spikes in two events with durations, bandwidths, relative bandwidths, and frequency-drift rates. The spikes at decimeter and meter wavelengths are again categorized based on their frequency-drift rates, such as positive, negative, and no measurable frequency-drift rates. We have carried out a statistical study on these categorized spikes. These statistical results and findings constrain solar radio spikes’ formation.

Thermal and dielectric properties of PVDF/PEO/SiO2 nanodielectrics for flexible radioelectronic device technologies

Hybrid polymer nanocomposites (HPNCs) are innovative multifunctional materials, which are developed and intensively studied for their uses in the rapid evolution of flexible and lightweight device technologies. Accordingly, to contribute in this area, thermal properties of the crystal phases and the broadband radio frequencies dielectric dispersion and relaxation behaviour of the HPNC films based on poly(vinylidene fluoride) (PVDF)/poly(ethylene oxide) (PEO)/silica (SiO2) are formulated and studied by employing differential scanning calorimeter (DSC) and impedance/material analyzer (IMA). DSC thermograms of these semicrystalline HPNCs explained the wide range alteration in the crystals melting temperature of PVDF (153–167 ​°C) and PEO (59–72 ​°C) and the total degree of crystallinity (4–87%) with varying compositional ratio over the entire range of the PVDF/PEO blend host matrix and the dispersed amount of amorphous SiO2 nanomaterial up to 15 ​wt%. The dielectric dispersion behaviour of these HPNCs, at 20 ​°C, confirmed a non-linear decrease in permittivity with the increase of applied radio wave electric field frequency from 1 ​MHz to 1 ​GHz, which lies in the range of 6 to 2. At a fixed frequency, dielectric permittivity values exhibited an uneven variation with the increase of SiO2 amount and also the modification in the composition of polymer blend matrix in these composites. The analysis of dielectric loss spectra and relaxation processes revealed that these are low loss dielectrics and the presence of SiO2 nanoparticles in the polymer blend matrix impedes the chain segmental dynamics and the dipole reorientation. The electrical conductivity of these HPNCs enhanced in the range of 10−8 to 10−4 ​S/cm with the increase in frequency but it changed anomalously when the constituent amounts of the formulated composites are varied. The polymer crystals thermal properties and the dielectric and electrical conductivity dispersion behaviour of these materials are demonstrated with the consideration of polymer-polymer and polymer-nanoparticle hybrid interfaces and interactions. The experimental results evidenced the behaviour of PVDF/PEO/SiO2 films as tunable nanodielectrics with their compositions and could be used as insulator and dielectric substrate materials in the advances of flexible radioelectronics and energy storage devices.

Terahertz phase modulator based on a metal-VO2 reconfigurable metasurface.

Actively controlling the phase of a terahertz (THz) wave is of great significance for beaming, tunable focusing, and holography. We present a THz phase modulator based on an electrically triggered vanadium dioxide (V O 2) reconfigurable metasurface. The unit cell of the device consists of two split-ring resonators embedded with a V O 2 ribbon. By electrically triggering the insulator-to-metal transition of V O 2, the resonance mode and resonance intensity of the unit cell can be dynamically controlled. The simulation results show that the structure can achieve a phase shift of about 360° in the range of 1.03-1.13THz, and the reflection amplitude can reach 80%. The device has potential applications in THz imaging, radar, broadband wireless communications, and array phase control.

Scaled and nonlinear multi-objective model for Downlink and Uplink exposure in massive MIMO

When designing wireless networks with a large number of wireless broadband devices, it is important to take into account the induced Uplink (UL) and Downlink (DL) exposure from base station broadcasting. This work focuses on the reduction of power consumption, low downlink and uplink electromagnetic exposure, and the optimization of locations and power levels of large Multiple Input–Multiple Output-Long Term Evolution base stations (MIMO-LTE). Additionally, it anticipates achieving maximum user coverage. In order to handle the power consumption and Electro Magnetic Field (EMF) exposure, a Nonlinear and Scaled Weight objective model (NLSW) is defined (DL and UL exposure). An enhanced Particle Swarm Optimization (PSO) technique is employed to resolve this optimization issue. Finally, DL exposure, UL exposure, and power performance of a NLSW are validated compared to the traditional linear model. Increased antenna leads to a 25% reduction in DL dosage. The minimum BS deployed in the area with the number of antenna elements until it reaches the ideal value is related to the UL exposure maximization.

Evaluating the impact of broadband access and internet use in a small underserved rural community

Having adequate access to the internet at home enhances quality-of-life for households and facilitates economic and social opportunities. Despite increased investment in response to the COVID-19 pandemic, millions of households in the rural United States still lack adequate access to high-speed internet. In this study, we evaluate a wireless broadband network deployed in Turney, a small, underserved rural community in northwest Missouri. In addition to collecting survey data before and after this internet intervention, we collected pre-treatment and post-treatment survey data from comparison communities to serve as a control group. Due to technical constraints, some of Turney's interested participants could not connect to the network, creating an additional comparison group. These comparisons suggest two primary findings, (1) changes in using the internet for employment, education, and health could not be directly attributed to the internet intervention, and (2) the internet intervention was associated with benefits stemming from the ability to use multiple devices at once. This study has implications for the design of future broadband evaluation studies, particularly those examining underserved rather than unserved communities. Recommendations for identifying appropriate outcome variables, executing recruitment strategies, and selecting the timing of surveys are made.