Wideband Communication Systems Research Articles

Design of 1450-1500nm Bismuth-doped Fiber Laser

With the rapid development of information technology, people's demand for the transmission capacity of fiber optic communication networks is increasing. How to broaden the bandwidth of communication systems has become one of the key issues in the field of communication. Researchers have found that the operating bandwidth of amplifiers mainly limits the bandwidth of communication systems. Although multiple solutions have been proposed and implemented to address this issue, there are still many gaps in the design of full-band multi wavelength-related light sources. By studying the three-level system of bismuth ions, the rate equation and power transfer equation of a bismuth ion doped fiber laser are simulated, and the pump power threshold and output power are calculated. Using MATLAB for simulation experiments, the relationship between laser power and pump power, as well as their variation with propagation distance, were ultimately obtained. The simulation results show that under 830 pump lights, the pump light threshold power is 10W. After reaching the threshold power, the pump light power and laser power have a linear relationship, and as the propagation distance increases, the pump light power gradually decreases and the laser power gradually increases. The analysis shows that the power generated by the signal light in this band meets the theoretical standards, which verifies the correctness of the scheme.

Design of a wideband vertically polarized omnidirectional antenna for covering 960–1250 MHz frequency band

This paper deals with the design and fabrication of a wideband vertically polarized omnidirectional antenna. The antenna unit of the array comprises four radiating dipoles fed by a parallel plate waveguide. A prototype is designed and measured in order to experimental verification. The acceptable agreement between the measurement and stimulation results validates the performance of presented antenna. The experimental results demonstrate that the VSWR < 2 impedance bandwidth of presented antenna can reach 97% from 0.64 to 1.84 GHz. Also, the maximum realized gain is about 5.2 dBi in the operating frequency range. The findings show that the antenna demonstrated has the capabilities to be used in wideband communication systems.

An optimization framework for RIS-based energy-efficient multi-cell NOMA systems

Non-orthogonal multiple access (NOMA) is a highly promising multiple access strategy for wideband communication systems due to its high spectral efficiency. However, in multi-cell multi-band systems, interference issues can arise from resource sharing among multiple users, which limits the potential of NOMA. To tackle these issues, in this paper, we study a NOMA system where reconfigurable intelligent surfaces (RIS) are employed across multiple cells with multiple users clusters. Specifically, we propose an optimization framework to maximize the system energy efficiency (EE) through jointly designing the transmission beamformer at each base station, the RIS phase shifts and the corresponding binary selection matrix indicating which elements of the RIS should be used to serve a specific cell. Our optimization framework takes into account the minimum rate requirements of users, the successive interference cancellation (SIC) decoding-based rate constraint, fairness among users as well as the maximum allowed transmission power. The resulting non-convex problem is solved by using an alternating optimization algorithm, wherein semidefinite programming (SDP), successive convex approximation (SCA), and penalty-based difference-of-convex (DC) programming are used to reach a solution. Simulation results show that the proposed system outperforms conventional orthogonal access in terms of EE performance, the achievable rate, and power consumption. Also, the results revealed the critical transmission power level for NOMA beyond which the EE starts decaying. Moreover, the proposed NOMA system shows a limited EE performance compared to the conventional orthogonal access as the number of clusters exceeds a certain limit.

Distributional Spectrum Series (DSS) with Beamforming in 5G Communication System

The transmission channel choice and other relevant characteristics affect the communication system's bandwidth loss and signal strength. This causes energy loss during transmission since the channel bandwidth is being used up so heavily. This may be avoided by carefully choosing the channels in the spectrum to allot the bandwidth in accordance with the consumption limit. In this study, the optimum energy reduction-based 5G communication system aids in improving the channel bandwidth selection in accordance with the prediction of the ideal antenna directionality. The Distributional Spectrum Series (DSS) and the beamforming method may be used to accomplish this. This kind of optimum antenna selection analyzes the signal spectrum and optimizes the energy based on the beamforming parameters by using directionality prediction from the Direction of Arrival (DOA). The testing results and comparative graphs demonstrate the performance of the proposed 5G communication system through parameters of Energy (Joule), Blocking Probability (BP), throughput (bps), and other relevant factors.

A Flexible Amplitude Equalizing Filter Based on Spoof Surface Plasmon Polaritons

In this article, an amplitude equalizing spoof surface plasmon polaritons (AESSPPs) filter deposited on flexible substrate is proposed for the first time. This new hybrid device can realize both the characteristics of amplitude equalization and interference filtering when embedding into a wideband communication system, which brings the compensation process of gain fluctuation back to the microwave front end instead of traditional complex algorithm in digital chip. It is mainly composed of equalizing thin layer and spoof surface plasmon polaritons (SSPPs) waveguide. The equalizing thin layer is realized by ITO (Indium Tin Oxide) and periodically sputtered along the propagation path of SSPPs waveguide to dissipate EM energy at different frequencies. In order to better reveal the nature property of equalization and filtering, an equivalent circuit of AESSPPs unit cell is proposed and analyzed theoretically. The equalizing value and bandwidth can be regulated independently by surface impedance of ITO thin layer and the structural parameter of SSPPs, respectively. Finally, we fabricated and measured three AESSPPs filter prototypes with different critical parameters. All the theory, simulation and measurement results are proved to have achieved the artificial dominated equalizing curve with different equalizing value and bandwidth, which validate that the proposed filter demonstrates the desired flexibility, equalization and filtering capabilities simultaneously.

Design and Development of Patch Loaded Slot Antenna for Super Wide band Communication System and MIMO Application

Design and Development of Patch Loaded Slot Antenna for Super Wide band Communication System and MIMO Application

Enhancing meta slot space space wavelength to solve blocking case in elastic optical networks

Elastic optical networks (EONs) are a promising technology for the development of flexible and wideband communication systems. The (FSU) frequency slot unit concept is used in this technology to define the bandwidth unit in the frequency domain. The use of a specified number of consecutive FSUs allows bandwidth to be assigned to a data stream in a flexible manner. Nonblocking optical switching networks are required for a successful elastic optical network operation. This article concentrates on the Wavelength Space Wavelength,Space, Wavelength switching network topologies that were previously presented. In comparison to the other architectures, the SSW switching fabric requires fewer Spectrum converters (SCs). n relation to Wavelength Space Wavelength, a prior study clarified that using the meta-slot approach reduces hardware complexity, which is measured by the number of frequency slot unit. A frequency range with one or more (FSUs) is called a meta-slot. The previous study did not discuss how to optimize the meta-slot class sizes, despite the fact that its effectiveness depends on the sizes of the meta-slot classes. Additionally, the use of meta-slots for Space Space Wavelength was not taken into account in the earlier analysis. The optimization of meta-slot class sizes is looked into in this study, and it is shown that this optimization may be modeled as the shortest path issue. For Wavelength Space Wavelength, the previously reported nonblocking conditions are contrasted with the meta-slot scheme optimized using the shortest path model. The outcome attests to the optimized meta-slot scheme's superiority. The distribution of meta-slots among S-switches is also crucial for Space Space Wavelength. The assignment of meta-slots is modeled as a bin-packing problem in the study. Thus, a well-known bin-packing heuristic can be used to find the assignment that is close to ideal. The number of S-switches is calculated for using the optimized meta-slot scheme and previously known nonblocking conditions. The outcome confirms that the meta-slot scheme benefits both Space, Wavelength and Wavelength Space Wavelength.

A Review on Massive MIMO Antennas for 5G Communication Systems on Challenges and Limitations

High data rate transfers, high-definition streaming, high-speed internet, and the expanding of the infrastructure such as the ultra-broadband communication systems in wireless communication have become a demand to be considered in improving quality of service and increase the capacity supporting gigabytes bitrate. Massive Multiple-Input Multiple-Output (MIMO) systems technology is evolving from MIMO systems and becoming a high demand for fifth-generation (5G) communication systems and keep expanding further. In the near future, massive MIMO systems could be the main wireless systems of communications technology and can be considered as a key technology to the system in daily lives. The arrangement of the huge number of antenna elements at the base station (BS) for uplink and downlink to support the MIMO systems in increasing its capacity is called a Massive MIMO system, which refers to the vast provisioning of antenna elements at base stations over the number of the single antenna of user equipment. Massive MIMO depends on spatial multiplexing and diversity gain in serving users with simple processing signal of uplink and downlink at the BS. There are challenges in massive MIMO system even though it contains numerous number of antennas, such as channel estimation need to be accurate, precoding at the BS, and signal detection which is related to the first two items. On the other hand, in supporting wideband cellular communication systems and enabling low latency communications and multi-gigabit data rates, the Millimeter-wave (mmWave) technology has been utilized. Also, it is widely influenced the potential of the fifth-generation (5G) New Radio (NR) standard. This study was specifically review and compare on a few designs and methodologies on massive MIMO antenna communication systems. There are three limitations of those antennas were identified to be used for future improvement and to be proposed in designing the massive MIMO antenna systems. A few suggestions to improve the weaknesses and to overcome the challenges have been proposed for future considerations.

Comparative Study of High Speed ADCs

With the development of information technology, analog-to-digital converter (ADC) is widely used. In products such as radar, ultra wideband communication system, high-performance digital oscilloscope and so on, the speed performance of analog-to-digital converter is usually the bottleneck of the whole system performance, so the research of high-speed ADC has attracted much attention. ADC is an interface circuit that converts analog signals into digital signals that can be processed by DSP. This paper will start with the basic knowledge of ADC, explain the general working process of ADC, introduce several architectures and working principles suitable for high-speed ADC, and compare and analyze their advantages and disadvantages.

Designing of 8-Gate Fingered GaN HEMT based Frequency Mixer with Enhanced Gain for Wide Band Communication Systems

The reconfigurable mixer plays an important role in both transmitter as well as receiver section in the present wireless and digital communication systems. Also such mixer requires lot of power for up-converting and down-converting the signal without any noise. This paper deals about such type of designing of reconfigurable mixer for wide band communication applications with Gallium Nitride High Electron Mobility Transistor (GaN HEMT). This GaN HEMT transistor solves the requirement of huge power over wide range without any noise. The mixer is designed in the present paper for variable gain conversion along with power consumption trade-off for a wide range of frequency (2–8 GHz) with reconfigurable concept. Applied Wave Research (AWR) simulator was used to design the reconfigurable mixer. The gain is controlled by changing the trans-conductance of the input RF stage, and the current steering in trans-impedance stage. A broadband down-converter mixer is designed that provide different conversion gain, ranging from 25–33.5 dB with two different modes. The large bandwidth of the mixer is achieved by shunting the trans-conductance stage and with various switching stages. The results also show that there is good isolation along with conversion gain of designed reconfigurable mixer, for wide range in various communication applications.

Analysis of LoRa Transmission Delay on Dynamic Performance of Standalone DC Microgrids

One important aspect toward proper and stable functioning of a communication-based controlled microgrid is data transmission. Consequently, an analysis of the effect of data transmission delay is of significance for any chosen communication protocol. This paper focuses on the effect of employing LoRa for data transfer at the secondary control level of a standalone DC microgrid. It analyses the effect of LoRa transmission delay on the dynamic performance of DC microgrids. This paper simulates a community DC microgrid that operates in three modes: PV mode, battery mode and generator mode. This microgrid operates as a centralized communication-based controlled microgrid, with the secondary control level operating as an event-driven level. The system incorporates a hierarchical system where data is transferred between the various distributed energy resources (DERs) local controllers and the microgrid central controller (MGCC). Simulations for three scenarios are presented. In the first scenario, the microgrid is designed and simulated without a communication delay to observe the system behavior. Then LoRa transmission delay is calculated for the various signals transferred between the MGCC and the local controllers. This delay is introduced into the simulation as transport delays and the system exhibits a level of stability degradation. Subsequently, a time delay compensation system is incorporated into the system for more robust operation. The delay compensation is applied in two simulation scenarios. In the first scenario, the system inductor (L) and capacitor (C) components are re-calculated, and the system is re-simulated to get a stable system even with the applied communication delay. In the second scenario, the proportional integrator (PI) controller in the microgrid central controller is re-designed to a more robust form to compensate for the delay caused by the LoRa transmission. The results obtained from the two modified simulations realize a stable DC microgrid. This system modification allows for system stability again, similar to the simulation when the microgrid operated without any communication delay. This, therefore, demonstrates that with proper system design and implementation, low bandwidth communication systems such as LoRa can be effectively employed for data transfer in event-driven communication-based controlled DC microgrids.

A modified broadband weighted magnitude‐selective behavioral model for digital predistortion of radio frequency power amplifiers

With the increasing demand for large signal bandwidth in communication systems, the complexity of the behavioral model of power amplifier (PA) will also increase. In this paper, a modified weighted magnitude-selective model based on magnitude-selective affine (MSA) function based model and weighted memory polynomial model is proposed to ensure low complexity and good modeling performance under broadband signal excitation. This model is constructed by using the power-dependent weighted function instead of the sum of multiple MSA functions in MSA. It can not only be used to solve the nonlinearity of PA excited by large bandwidth signal but also reducing the model coefficients without affecting the modeling performance makes the digital predistortion of large bandwidth signals more simple and effective. In this paper, a 100 MHz broadband signal is used for simulation and experiment on a wideband PA. The results show that for the same performance the WMA model required approximately 80% less coefficients.

InFocus: A Spatial Coding Technique to Mitigate Misfocus in Near-Field LoS Beamforming

Phased arrays, commonly used in IEEE 802.11ad and 5G radios, are capable of focusing radio frequency signals in a specific direction or a spatial region. Beamforming achieves such directional or spatial concentration of signals and enables phased array-based radios to achieve high data rates. Designing beams for millimeter wave and terahertz communication using massive phased arrays, however, is challenging due to hardware constraints and the wide bandwidth in these systems. For example, beams which are optimal at the center frequency may perform poor in wideband communication systems where the radio frequencies differ substantially from the center frequency. The poor performance in such systems is due to differences in the optimal beamformers corresponding to distinct radio frequencies within the wide bandwidth. Such a mismatch leads to a misfocus effect in near-field systems and the beam squint effect in far-field systems. In this paper, we investigate the misfocus effect and propose InFocus, a low complexity technique to construct beams that are well suited for massive wideband phased arrays. The beams are constructed using a carefully designed frequency modulated waveform in the spatial dimension. InFocus mitigates beam misfocus and beam squint when applied to near-field and far-field systems.

Wideband Receive Beamforming Based on 4-D Antenna Arrays With Postmodulation

A wideband receive beamforming configuration and method based on four-dimensional (4-D) antenna arrays with postmodulation is proposed. Two pairs of single-pole-triple-throw switches are utilized for beamforming at the center frequency. Postmodulation is introduced to increase the degree of freedom of 4-D antenna arrays and achieve a deep null point at the steering direction of sidebands power pattern. The reception of 16 quadrature amplitude modulation signal, whose bandwidth is larger than the time modulation frequency, is implemented by a 16-element 4-D dipole array. The results of wideband beamforming show that the sidebands power at the steering direction can be eliminated ideally, whereas the sidelobes level of averaged radiated power pattern is suppressed to a low value. The 4-D array with postmodulation shows obviously improved bit error rates performance as compared to the 4-D array with conventional beamforming method and phased arrays, which confirms that the 4-D array with postmodulation has potential advantages in the application of wideband communication systems.

Performance Evaluation of WDM Optical Fiber Communication System in the presence of PMD

This paper investigates for rising optical fiber transmission strength, increasing bandwidth, and decreasing communication system weakness by using wavelength division multiplexing (WDM). WDM gives today's distention speed and communication traffic. Systems using WDM faces nonlinearities, which the most intensive nonlinear attack is, four wave mixing (FWM). FWM creates and increases crosstalk between WDM channels as a result slows down and impairs the performance of the communication system. This investigation uses orthogonal frequency division multiplexing (OFDM) for evaluating execution of WDM fiber system by repairing Polarization Mode Dispersion (PMD). We took results in the case of trying PMD-Emulator and without trying PMD-Emulator in the system design. We compared the results got in both cases. Furthermore, we compared the performance of the system with the investigations done using different ways, methods, and techniques for compensating PMD and FWM appears in WDM systems. As PMD-Emulator, helps enhancing the system design performance, and OFDM gives the feature of robustness and useful execution to the system. OFDM examined by appointing interfered orthogonal signal sets, for 16 channels; with equally spaced OFDM channels. Oure results showed that the optical fiber communication system using OFDM technique gives perfect removing FWM signal crosstalk, and accurate data transmission, comparing to other techniques used in other researches. We got a decreased FWM power to -77dBm, and the BER of -0.317. Furthermore, the system quality increased with applying PMD-Emulator and OFDM. In addition, using PMD-Emulator in the system design raised the results effectiveness. The program used in the present work is optisystem-15, and the results obtained in this study coincide with the theoretical and actual results obtained by the previous studies.

Method for prediction of EMI Emissions from Automotive Ethernet to Vehicle Antennas

Abstract. In automotive application new point-to-point (P2P) wideband communication systems e.g. Automotive Ethernet 100BASE-T1 imply an increasing effort in safeguarding its electromagnetic compatibility (EMC). The state-of-the-art EMC safeguarding process proposes a pre-compliant system level test before the vehicle level test, which may have significant variation in test results due to the different electromagnetic environment. This work presents an approach to calculate the emission signal at the vehicle antenna from the ECU output signal given by the power spectral density (PSD) of the Automotive Ethernet ECUs. The determination is performed via a transfer function which describes the coupling between the Ethernet wire harness and the antenna. This approach considers the modelling of the complex vehicle environment by the transfer function which promises the determination of an accurate emission signal before performing the vehicle level test. Further, the transfer function for a specifically EMC critical cable harness routing along the cockpit area is analyzed in more detail with a 3D simulation, which validates the chosen measurement technique of the transfer function.

Wideband Channel Estimation for IRS-Aided Systems in the Face of Beam Squint

Intelligent reflecting surfaces (IRSs) improve both the bandwidth and energy efficiency of wideband communication systems by using low-cost passive elements for reflecting the impinging signals with adjustable phase shifts. To realize the full potential of IRS-aided systems, having accurate channel state information (CSI) is indispensable, but it is challenging to acquire, since these passive devices cannot carry out transmit/receive signal processing. The existing channel estimation methods conceived for wideband IRS-aided communication systems only consider the channel's frequency selectivity, but ignore the effect of beam squint, despite its severe performance degradation. Hence we fill this gap and conceive wideband channel estimation for IRS-aided communication systems by explicitly taking the effect of beam squint into consideration. We demonstrate that the mutual correlation function between the spatial steering vectors and the cascaded two-hop channel reflected by the IRS has two peaks, which leads to a pair of estimated angles for a single propagation path, due to the effect of beam squint. One of these two estimated angles is the frequency-independent `actual angle', while the other one is the frequency-dependent `false angle'. To reduce the influence of false angles on channel estimation, we propose a twin-stage orthogonal matching pursuit (TS-OMP) algorithm.

Design and research of a miniaturized four notch UWB antenna

In order to effectively suppress the interference of narrow-band communication systems such as WiMAX band, international satellite band, X band and the ITU band, this paper designs a miniature ultra wideband (UWB) antenna. The improved rectangle is used as the radiation patch. The semicircular groove is dug in the upper part of the rectangle and the two corners below are cut off. The long triangle is also cut on both sides of the end of the microstrip line. The fish bone groove is well modified in the middle of the rectangular ground plate to obtain the perfect ultra wideband characteristics. By digging a semi-circular groove on the radiation patch to introduce T-shaped branches, and opening an inverted U-shaped groove in the center of the radiation patch, introducing symmetrical C-shaped open branches on both sides of the feeder line and etching U-shaped narrow gaps on the feeder line, four band notch characteristics of 3.24−3.8 GHz, 4.5−4.97 GHz, 7.24−7.76 GHz and 8.0−8.54 GHz are produced, which better suppresses the interference in the notch band, shows that the antenna can work normally in the frequency band of 3.0−13.09 GHz, and the four notch baud property of the antenna also expands the application field, which is suitable for many ultra wideband communication systems.

An All-in-One Dual Band Blade Antenna for ADS-B and 5G Communications in UAV Assisted Wireless Networks.

This paper is aimed at the characterization and manufacturing of an SMA coaxial fed compact blade antenna with dual frequency characteristics for broadband applications on board of Unmanned Air Vehicles (UAVs). This antenna is linearly polarized, and it combines the benefits of Automatic Dependent Surveillance-Broadcast (ADS-B) and 5th Generation (5G) communications in one single element, covering both the 1.030–1.090 GHz and the 3.4–3.8 GHz bands thanks to a bent side and a ‘C’ shaped slot within the radiation element. Starting from the simulation outcomes on an ideal ground plane, the results are here extended to a bent ground plane and on two UAV commercial CAD models. Details of manufacturing of the antenna in both aluminium and FR-4 substrate materials are presented. The comparison between measurements and simulations is discussed in terms of return loss, bandwidth, gain, and radiation pattern. Results show an antenna with a low profile and a simple structure that can be employed in various wideband communication systems, suiting future UAV assisted 5G networks while being perfectly compliant with forthcoming ADS-B based Detect-And-Avoid (DAA) technologies in Unmanned Aerial Traffic Management (UTM).

Optimizing meta-slots for nonblocking elastic optical switching networks

Elastic optical network is a promising technology for building flexible and wideband communication systems. This technology features the frequency slot unit (FSU) concept, which defines the bandwidth unit in the frequency domain. The utilization of a specified number of consecutive FSUs allows the bandwidth to be flexibly assigned to a data stream. For a successful elastic optical network operation, the use of nonblocking optical switching networks is indispensable. This paper focuses on two previously proposed W-S-W switching network architectures, namely, WSW1 and WSW2. With regard to WSW1, a previous study elucidated that the hardware complexity, which is evaluated by the number of FSUs, decreases by employing the meta-slot scheme. A meta-slot is a frequency range containing one or more FSUs. Although its effectiveness depends on the sizes of meta-slot classes, the previous study did not present how to optimize the meta-slot class sizes. Moreover, the employment of meta-slots was not considered for WSW2 in the previous study. This paper investigates the optimization of meta-slot class sizes and demonstrates that such optimization is modeled as the shortest path problem. For WSW1, the meta-slot scheme optimized by the shortest path model is compared with the previously reported nonblocking conditions. The result confirms the superiority of the optimized meta-slot scheme. For WSW2, the assignment of meta-slots among S-switches is also essential. The paper models the assignment of meta-slots as a bin-packing problem. Thus, the near-optimal assignment can be obtained by a known bin-packing heuristic. For WSW2, the number of S-switches is evaluated for the optimized meta-slot scheme and the previously known nonblocking conditions. The result confirms that the meta-slot scheme is advantageous for WSW2 as well as for WSW1.