High-speed Communication Research Articles

IRS-Aided Wireless Relaying for High-Speed Train Communication: Beamforming Design and Channel Estimation

IRS-Aided Wireless Relaying for High-Speed Train Communication: Beamforming Design and Channel Estimation

Metasurface-based High-Speed Photonic THz OAM Communication System

Metasurface-based High-Speed Photonic THz OAM Communication System

Micro-Trench Deep-Ultraviolet LEDs with Boosted Efficiency for High-Speed Solar-Blind Optical Communication

Micro-Trench Deep-Ultraviolet LEDs with Boosted Efficiency for High-Speed Solar-Blind Optical Communication

DESIGN OF MIMO ANTENNA FOR WIDEBAND THz MOBILE COMMUNICATIONS

In the network era of radio waves, as the need constantly continues to grow at the current level, new radio frequency bands must be found. With 5G technology being replaced, the terahertz (THz) frequency band is expected to be the most suitable resource to power wireless networks within the range of 0.1 THz up to 10 THz. This article describes a model of an ultrawideband 2 × 2 multiple-in, multiple-out (MIMO) antenna for THz applications. As the frequency moves upward, the cross-coupling of the lead elements between elements becomes an inevitable problem that brings undesirable effects on the overall efficiency of the antennas. Hence some practices have been introduced to reduce the mutual coupling impact on MIMO antenna measurements like high isolation, parallel configuration, parasitic structures, and feeding slots. The model presented in this paper comes with a radiation radiator of a 133 × 255 μm<sup>2</sup> rectangular shape with a circular cut in the middle. The designed structure has a large bandwidth typically ranging from 5.5 THz to 10 THz, and hence, it can be utilized in high-speed wireless communication networks and in working with high bit rates. The antenna performance is also conducted in terms of a number of factors like channel capacity loss and total active reflection coefficient. Following this, it is compared with other existing designs. By comparing the resulting model and existing standards in different parameters, it proves that the model is superior to existing designs.

ПОШИРЕННЯ ТЕРАГЕРЦОВИХ ВИХРОВИХ ЛАЗЕРНИХ ПУЧКІВ У ВІЛЬНОМУ ПРОСТОРІ

Subject and Purpose. Currently, numerous ideas and different methods have been in growth for generating vortex beams — areas of the circular motion of the electromagnetic wave energy flow around the so-called phase singularity points caused by a violation of the wave front topological structure. The purpose of this work is to obtain analytical expressions describing the nonparaxial diffraction of wave modes of the waveguide resonator of a terahertz laser during the wave mode interaction with a spiral phase plate. The resulting vortex beams are examined for their physical features in free space propagation. Methods and Methodology. The Rayleigh-Sommerfeld vector theory is adopted to consider the propagation of vortex laser beams generated by wave modes of the quasi-optical waveguide cavity when interacting with a spiral phase plate in different diffraction zones. Results. For the first time, analytical expressions have been obtained to describe the nonparaxial diffraction of wave modes of the waveguide resonator of a terahertz laser, when resonator modes interact with a spiral phase plate at different topological charges, n. The physical features of the resulting vortex beams were studied in their free space propagation. It has been shown that a spiral phase plate modifies the structure of the linearly polarized EH₁₁ mode so that the original (n=0) intensity profile with the maximum energy at the center turns at n=1 and 2 into a ring-like donut shape with an energy hole in the center. The azimuthally polarized TE₀₁ mode has originally (n=0) a ring-shaped intensity. At n=1, this configuration changes to have the maximum intensity in the center. At n=2, it becomes annular again. In the process, the spherical phase front of the beam of the linearly polarized EH₁₁ mode becomes spiral and have one singularity point on the axis, whereas the phase structure of the azimuthally polarized TE₀₁ mode gains a region with two phase singularity points off the axis. Conclusions. The results of the study can effectively facilitate information transfer in high-speed THz communication systems. They can provide a real platform to perform tasks related to tomography, exploring properties of materials, detecting astrophysical sources, which makes them very promising in modern technologies.

Nonlinear equalizer based on neural network in high-speed optical fiber communication systems

Nonlinear equalizer based on neural network in high-speed optical fiber communication systems

Challenge and Prospect of High-speed Rail Radar Communication Integration Technologies

Radar plays an important role in urban public transit system, so it is of great significance to ensure the safe operation of High-speed rail. Radar communication integration technology has the characteristics of high efficiency and low energy consumption, it can improve communication quality, speed up transmission efficiency and improve detection accuracy. Firstly, this paper introduces the running scene of High-speed rail, and puts forward that radar communication integration technology has a broad application space in High-speed rail. Then it introduces radar communication integration technology, and the research status, advantages and development prospects of radar communication integration technology based on linear frequency modulation（LFM）. Finally, it is proposed that obstacle detection technology is one of the difficulties to ensure the safe operation of High-speed rail. Radar integration technology can be effectively applied to train obstacle detection, which is an important technical support for improving service quality and speeding up the intelligent construction of High-speed rail in the future.

A Review on Deployment of UAV-FSO System for High-Speed Communication

A Review on Deployment of UAV-FSO System for High-Speed Communication

CRaTeBo: a high-speed, radiation-tolerant and versatile testing platform for FPGA radiation qualification for high-energy particle accelerator applications

The CHARM Radiation Tolerant FPGA Tester Board (CRaTeBo) is a FPGA testing platform for the CERN High-energy Accelerator (CHARM) irradiation facility. It is meant to ease the radiation testing of FPGA-based systems by providing users with a radiation-tolerant carrier card featuring an FPGA interface, a high-speed communication interface, a flexible power supply, and an HPC-FMC connector for additional front-end electronics. It is foreseen to be a permanent installation in the CHARM facility at CERN, giving users the possibility to carry out radiation tests of their system with minimum effort on the test setup development.

Research on high-speed communication mechanism of time-triggered network based on RGMII

Research on high-speed communication mechanism of time-triggered network based on RGMII

Method for the Simultaneous Generation of Two Nonlinear Pseudo Random Sequences: 5-ary and Binary

Multi-level signals and sequences have become a significant aspect of modern high-speed communication systems. Hence, to ensure the confidentiality and integrity of the transmitted information, advanced methods and devices are necessary to produce strong cryptographic properties for not only binary but also for nonbinary keystreams, which can be used in resource-constrained microcontrollers. The proposed method and apparatus generate both a balanced nonlinear 5-ary pseudo-random sequence and a binary keystream sequence. The nonlinearity is determined by applying shrinking and multiplexing techniques to the generated linear 5-ary pseudo-random sequence and the running zero in its conversion to a binary balanced sequence.

High-Efficiency Multi-Channel Orbital Angular Momentum Multiplexing Enabled by the Angle-Dispersive Metasurface.

Orbital angular momentum (OAM) multiplexing of electromagnetic (EM) waves is of great significance for high-speed wireless communication and remote sensing. To achieve high-efficiency OAM multiplexing for multi-channel incident EM waves, this paper presents a novel angle-dispersive meta-atom structure, which can introduce the required anti-symmetric phase dispersion as well as high transmission efficiency for OAM multiplexing. These meta-atoms are then arranged delicately to form an angle-dispersive metasurface working at the X band, which enables three-channel OAM multiplexing by converting highly directional transverse-magnetic (TM) waves incident from 0 and ±45° to coaxial OAM beams with l = 0 and ±2 modes, respectively. The simulation and experimental results reveal that the proposed metasurface can convert a higher proportion of energy to the required OAM modes compared to the conventional OAM multiplexing metasurfaces, which can significantly improve the coaxial transmission efficiency of multi-channel OAM multiplexing.

Conditional Most-Correlated Distribution-Based Load-Balancing Scheme for Hybrid LiFi/WiGig Network.

A hybrid network has recently been proposed as a framework for a high-speed wireless communication network. Basically, it integrates light fidelity (LiFi) with radio frequency wireless gigabit alliance (WiGig) networks that operate, simultaneously, in a completely different frequency band. To assign the best access point (AP) and provide enough resources for each user, an effective load-balancing (LB) strategy is needed. However, the traditional LB strategies involve sophisticated iterative computing procedures whenever the user distribution changes. Hence, the first contribution of this work is to offer a more adaptable, two-step, conditional, and most-correlated distribution (CMCD) algorithm. Thus, the low-complexity most-correlated distribution (MCD) LB scheme is applied, and the average data rates for all users are then calculated. If the results achieve the predefined performance threshold (PDT), the decisions will be confirmed; otherwise, the proposed scheme automatically switches to the more accurate, but more complex, consecutive assign WiGig first separate optimization algorithms (CAWFS) algorithm. The suggested algorithm provides a clear performance-complexity trade-off, which could be simply controlled by choosing the suitable performance tolerance factor. The second contribution of this paper is the correlation-weighted majority voting (CWMV) method, which attempts to benefit from as many prior decision votes as possible, instead of relying just on one vote. In the CWMV technique, the weight of each vote is calculated based on the correlation between the history distribution vectors and the new user distribution vector. A significant increase in the system performance is evident from the simulation results.

Characterization and Validation of PAM4 Signaling in Modern Hardware Designs

To satisfy rising data capacity and bandwidth demands, Pulse Amplitude Modulation with 4 levels (PAM4) has become a popular signaling system in high-speed digital communication. As contemporary hardware designs restrict Non-Return-to-Zero (NRZ) signaling, PAM4 offers an appealing alternative by doubling data flow within the same bandwidth. Using PAM4 signaling provides distinct characterisation and validation problems that must be addressed to assure dependable performance in modern hardware systems. Modern hardware designs' PAM4 signaling characterisation and validation are covered in this research report. PAM4 signaling fundamentals, including modulation technique, signal integrity, and high-speed data transfer, are examined in the research. PAM4's higher data rates and spectrum efficiency are highlighted in the article, along with its implementation issues. Much of the study characterizes PAM4 signaling. This involves developing reliable signal measuring methods, analyzing signal loss owing to ISI and jitter, and assessing PAM4 performance based on hardware components. PAM4 signal behavior under diverse settings is characterized using advanced methods as eye diagram analysis, constellation diagram evaluation, and error vector magnitude (EVM) measurement. The paper tests and simulates PAM4 signaling to validate it. A thorough approach for testing PAM4 performance in lab and real-world conditions is provided. PAM4 signaling resilience in different hardware contexts is tested using specialist test equipment and simulation tools. The validation method includes BER, SNR, and industry standard compliance.The study also examines how new hardware design affects PAM4 signaling. Advanced circuit design, packaging, and material qualities affect signal integrity and performance. High-speed data interface designers and engineers may learn from the paper's ideas for reducing signal degradation and improving PAM4 signaling in complicated hardware systems.

Designing an active electronically scanned array as part of onboard equipment of a high-speed radio communication channel

The active electronically scanned array being developed is designed to provide an all-weather high-speed radio communication channel “Spacecraft – Earth”. It is supposed to provide fast, inertia-free observation of space by swinging the antenna beam electrically, and, in fact, is a dynamic space-time filter of the spacecraft. The aim of the work is to identify the basic principles of functioning of the array as part of the spacecraft with inherent limitations in the mass-dimensional and energy characteristics of the onboard equipment and, at the same time, high requirements for the functional characteristics. This paper presents the calculation and the main results of designing an active electronically scanned array complying with the requirements for optimizing the parameters of the antenna system. To assess the effect of scanning on the phase characteristics of the chips, a nonlinear amplifier model was developed. A statistical analysis of the phase characteristics was carried out when the load resistance changed in accordance with the obtained distribution laws. When calculating the resulting directional pattern of the antenna array, destabilizing factors were taken into account in accordance with the results of the study of the prototypes of the antenna array being created. Phase errors were calculated, mainly determined by the errors of the terminal parts of the receiving paths. Measures were implemented to ensure the effect of such phase errors on the directional pattern of the array only on the far side lobes.

Separation and detection of orbital angular momentum states of composite vortex beams in atmospheric turbulence channels

The separation and detection of compound orbital angular momentum (OAM) modes are the basis for achieving high-speed and high-capacity communication, but the atmospheric turbulence causes distortion of the phase fronts of vortex beams, which hinders the recognition of OAM modes. To solve this problem, in this work, we propose and investigate a joint scheme of combining the Gerchberg–Saxton (GS) algorithm and the phase of addition and subtraction model that can achieve high recognition accuracy and a wide range of OAM modes of compound perfect optical vortex beam under long-distance turbulence environment. At the receiving end, the GS algorithm and phase addition and subtraction are used to compensate and modulate the incident vortex light field to obtain the pre-processed light field, and then the OAM is detected by the coordinate transformation method. The simulation results show that: The detection range of the OAM of the three optical path detection model for the vortex beam transmitting 1000 m reaches −37 to +37 in the vacuum environment, and the mode purity of −37 to +37 can reach more than 0.3 when the turbulence intensity is Cn 2 = 2 × 10−15 m−2/3. The detection range of the OAM of the vortex can be further expanded by increasing the optical path. This study provides a new method for the separation and detection of OAM of composite vortex beams.

O-Shape Fractal Antenna Optimized Design with Broad Bandwidth and High Gain for 6G Mobile Communication Devices

Optimization of antenna parameters is important for achieving the best design that has higher results for gain and bandwidth while also having a smaller size. One such antenna design is numerically investigated and presented in this research. The antenna is optimized to an O-shape fractal design from a square patch design. The antenna is created by etching a slot of a square patch and making an O-shape fractal metamaterial patch antenna that operates on the THz band. The THz patch antenna is also investigated for its metamaterial properties. The optimization of the THz patch antenna is carried out for substrate height, slot length, and slot width. The optimized design has a size of 65 × 65 µm2. The highest bandwidth of 31.4 THz (138%) and the highest gain of 11.1 dBi is achieved. The optimized design is then investigated for multiple elements. The two-element MIMO antenna design using an O-shape patch is investigated to observe its performance and compare it with an O-shape single-element design. The two-element MIMO antenna design gives two bands with a bandwidth of 18 THz (113%) and 21 THz (56%). The gain of this design is 5.18 dBi and the size is 130 × 65 µm2. A comparison between the O-shape single-element fractal design, two-element fractal MIMO design, and other published designs is carried out. The compact, broadband, and high gain design presented can be used for 6G high-speed mobile communication devices.

High-speed physical layer secure communication scheme based on synchronous chaotic and electro-optic self-feedback dual-phase encryption

In this paper, a novel secure communication scheme based on temporal spreading and dual-phase perturbation is proposed to improve security at the physical layer. For one thing, the traditional electro-optical feedback phase encryption system is significantly sophisticated by the introduction of additional synchronized chaotic phase encryption. Besides, more keys in this system are available, with the attendance of dispersion and optical chaos, the key space is notably enhanced to ∼236, resisting the eavesdropping attacks. After passing through a series of encryption devices, the information is ultimately displayed as a noise-like signal. A 32 Gb s−1 on-off keying signal is successfully transmitted over a 100 km standard single-mode fiber. Simulation results show that by selecting the appropriate system parameters, a bit error rate as low as 10−10 can be obtained for legitimate terminals, and the effect of different hardware parameter mismatches on the decryption performance is also investigated which indicates a certain tolerance range for the mismatch of each parameter. This paper provides a new idea to combine an electro-optical feedback system with optical chaos to establish optical secrecy communication.

Designing high-speed GEO-to-Moon optical wireless communication links

Moon exploration and colonization will strongly rely upon high-speed optical wireless communications over a huge distance (around 400,000 km). Here, we introduce a holistic model, including the propagation issues as well as the realistic communication limitations and the expected practical limitations. We focus on the communication issues in a link connecting a GEO satellite to a fixed Moon optical station: here, we consider the challenging 10 Gbit/s transmission rate, and we assume an optical pre-amplified receiver, which is today the only option for high speed; we then select three different modulation formats, with corresponding implementations and increasing complexity and performance. Under these assumptions, we estimate the common operating conditions at the forward error correction threshold and point out the role of the transmitter and receiver telescopes: for practical size (e.g., 1 m), relevant limitations arise, which we combine with the typical photons-per-bit sensitivity values in an optical link. We find that all considered modulation formats can be used at 10 Gbit/s, although with different margins and hardware requirements, particularly considering the size of the optical antennas. We then extend the analysis to higher rates, up to 40 Gbit/s. This work can open the way to the realization of optical wireless communication systems to/from the future Moon Village.

Enhanced bandwidth of a lateral-pin Ge/Si avalanche photodiode using inductive gain peaking

Lateral-pin germanium silicon avalanche photodiodes (APDs) offer great potential for improving performance, cost-effectiveness, and versatile production processes for large-capacity data communication applications. However, excessive avalanche multiplication noise limits the increase in bandwidth. In this study, we propose and design the integrated peaking inductors to enhance the bandwidth of a lateral pin Ge/Si APD without compromising the direct current (DC) characteristics. By introducing the spiral inductor to counteract the capacitive effect of APD, the RF output power at high frequency can be effectively increased, thus improving the photodiode bandwidth. The impact of different sizes of inductors and APDs on the performance was experimentally investigated. The resulting APDs, with Ge lengths of 20μm (Ge20) and 45μm (Ge45), provided low dark currents of 11 nA and 27 nA, and primary responsivities of 0.85 A/W and 1.05 A/W at −1 V, respectively. A small inductor (375 pH) exhibited greater bandwidth enhancement than a large inductor (622 pH) and the Ge20 APD achieved a bandwidth of up to 78 GHz. For the larger Ge45 APD, the bandwidth was maintained above 50 GHz, even close to the breakdown voltage, and a high gain-bandwidth product of up to 609 GHz was calculated by an avalanche multiplication gain of 11.7. This result may provide ideas for balancing the speed and sensitivity of lateral-pin APDs used in high-speed optical communications.