Transmission Capacity Research Articles

Surface wave communication-based wave guide design concerns for flip chip package-based integrated circuits with bump pitch sizes of 1.2 mm and above

ABSTRACT The flip chip package (FCP) based integrated circuits supports millimetre wave frequency range (30 - 300 GHz), analysing the conditions for optimal signal transmission between the integrated circuits for FCP type being the primary essence of this article. The effective signal transmission occurs through a dielectric-coated conductor structure based on the surface wave communication phenomenon, known as a surface wave communication-based wave guide (SWW). The article focuses primarily on design considerations to build SWW for FCP applications at millimetre wave frequency ranges. The efficiency of the proposed waveguide was investigated in terms of power transmission capacity, voltage standing wave ratio (VSWR) and signal attenuation. The analysis comprises examining these parameters at the frequency range of 50 GHz to 150 GHz while taking into account varied degrees of waveguide dimensions and surface reactance. The measured results show that at the signal frequency of 100 GHz with dielectric and conductor thickness of 0.2 mm and surface reactance of 100 Ω, the suggested waveguide provides efficient signal transmission with approximately 0 dB signal attenuation, ideal high-power flow of 41,000 VA m 2 and VSWR of 1.2. Overall, this article provides insights on the design and performance of SWW for FCP applications at millimetre wave frequency band.

SC and OFDM hybrid coherent optical transmission scheme based on 1-bit bandpass delta-sigma modulation.

High-order quadrature amplitude modulation (QAM) can effectively improve the capacity and spectral efficiency of coherent optical transmission systems. However, as the modulation order increases, the signal becomes less tolerant to noise and nonlinear effects during transmission, and the implementation cost also increases. We propose a single carrier (SC) and orthogonal frequency division multiplexing (OFDM) hybrid coherent optical transmission scheme based on a 1-bit bandpass (BP) delta-sigma modulation (DSM). The driving I-channel and Q-channel signals for the optical in-phase/quadrature (I/Q) modulator carry SC-modulated and OFDM-modulated transmitter data, respectively. Optical quadrature-phase-shift-keying (QPSK) modulation is realized by the 1-bit DSM quantizer and I/Q modulator, which can effectively suppress quantization noise and reduce the complexity of digital signal processing (DSP) and the performance requirements of optoelectronic devices. In addition, the hybrid transmission of SC and OFDM can balance the advantages of both to meet the variable channel conditions and complex application scenarios. High-fidelity transmission of SC 512QAM and OFDM 512QAM hybrid signals, in the form of a 60 Gbaud optical QPSK signal, over 60 km single-mode fiber-28 (SMF-28) is verified by offline experiments, and the bit error rates (BERs) of both SC 512QAM and OFDM 512QAM are below the hard-decision forward-error correction (HD-FEC) threshold of 3.8e-3.

Channel estimation for reconfigurable intelligent surface‐assisted mmWave using multidimensional Runge Kutta orthogonal matching pursuit algorithm in MIMO systems

SummaryIn the context of Reconfigurable Intelligent Surface (RIS) assisted millimeter wave communications within the Multiple Input Multiple Output (MIMO) system, Channel Estimation (CE) poses a significant challenge due to signal sparsity and blockages between transmitters and receivers. Consequently, communication faces difficulties without a direct line‐of‐sight path, leading to increased pilot overhead. To address these obstacles, this research introduces a channel estimation approach for RIS‐aided millimeter wave communication employing the Multidimensional Runge Kutta Orthogonal Matching Pursuit (MRKOMP) algorithm in MIMO systems. The proposed method aims to enhance network coverage and channel capacity for efficient data transmission. By utilizing the multiscale cumulative residual distribution entropy function, the method establishes an indirect path when the line‐of‐sight is obstructed. Furthermore, the multidimensional orthogonal matching pursuit methodology calculates sparsity levels and facilitates sparse recovery. Optimization of the weight parameter through the Runge Kutta optimizer effectively eliminates sparsity, resulting in improved spectral efficiency and RIS gain. Simulation results demonstrate a significant 99.9% enhancement in network capacity and spectral efficiency compared to existing methods.

Equalization system of low differential mode delay few-mode fibers based on the neural network MIMO algorithm.

In recent years, with the development of information networks, higher requirements for transmission capacity have been recommended. Yet, at the same time, the capacity of single-mode fiber is rapidly approaching the theoretical limit. The multidimensional multiplexing technique is an effective way to solve this problem. Since the high differential mode delay (DMD) of transmission fiber increases the complexity of demultiplexing in equalization algorithms, we use an intelligent design method to optimize the trench-assisted gradient refractive index structure in this paper. The maximum DMD of the optimized optical fiber structure is 19.6 ps/km. A least mean squares-feedforward neural network constant modulus algorithm (LMS-FNNCMA) is also designed by using the theory of the least mean squares (LMS), constant modulus algorithm (CMA), and the multiple input multiple output (MIMO) neural networks. In order to verify the accuracy of the algorithm, a polarization division multiplexing-wavelength division multiplexing-mode division multiplexing (PDM-WDM-MDM) optical transmission system is constructed through simulation. The algorithm successfully realizes the de-crosstalk over a transmission distance of 1200 km at a rate of 1.2 Tbps under simulation conditions.

Ultrahigh-fiber systems transmission capacity based on efficient optical single-/multi-mode band fiber parameters

Ultrahigh-fiber systems transmission capacity based on efficient optical single-/multi-mode band fiber parameters

Net gain in C+L band from LED pumped broadband emission in Er3+-doped oxyhalide tellurite glass

Expanding gain bandwidth into the L-band for erbium-doped fiber amplifiers (EDFAs) is a crucial strategy to overcome limitations in prevalent C-band focused commercial silica-based EDFAs, significantly boosting optical network transmission capacity. Herein, we synthesized Er3+-doped broadband near-infrared emission tellurite glasses utilizing the melt quenching process, systematically exploring the impact of ZnCl2 on the glass structure and optical properties. The 82TeO2–3Nb2O5–15ZnCl2–3Er2O3 (TNZ15) glass emerged as a standout candidate for broadband amplifiers around wavelength at 1.55 μm. With escalating ZnCl2 concentration, a discernible red shift in the emission peak wave lines was observed, accompanied by an expansion of the full width at half maximum (FWHM) from 98 nm to 106 nm. Noteworthy characteristics of all samples included exceptional thermal stability and elevated near-infrared (NIR) transmittance. Application of the Judd-Ofelt (J-O) theory facilitated the calculation of J-O parameter intensity, providing deeper insights into the optical behavior of the materials. Finally, the evaluation of TNZ15 planar optical waveguides, employing the vertical top pumping mode of two 980 nm LEDs, encompassed both the C-band (1530–1565 nm) and the L-band (1565–1625 nm). The results underscore the potential of TNZ15 glass as a promising gain material for broadband optical amplifiers and lasers, offering valuable insights into the development of next-generation optical amplification technologies.

Low-Frequency and Sub-Synchronous Power Oscillation Suppression and Analysis of Hybrid Line Commutated Converter for HVDC Grid

Building high-proportion renewable energy grid requires economical and reliable High Voltage Direct Current (HVDC) converters. Line Commutated Converter (LCC) is widely used because of its long transmission distance, low power loss, low manufacturing cost, and large transmission capacity, which modular multilevel converter (MMC) cannot achieve, but has commutation failure (CF) problems. Low-frequency and sub-synchronous power oscillation caused by CF will affect the safety of bulk power systems. This paper theoretically analyzes the power oscillation during CF and CF recovery, and then proposes a novel hybrid line commutated converter (H-LCC) based on integrated gate commutated thyristor (IGCT), which can effectively mitigate CF and suppress power oscillation. The principle of H-LCC suppressing power oscillation is analyzed. On this basis, the performance of LCC, MMC and H-LCC under the same fault conditions is compared by a simulation study, which proves that H-LCC can improve the security and stability of high-proportion renewable energy power systems.

Multi-criteria model for selection of optical linear terminals based on FUZZY TOPSIS method

Optical networks are an integral part of modern telecommunication systems. Huge traffic and ever-increasing requirements for data transmission capacity and quality encourage the wider use of modern optical technologies in telecommunications. The rational choice of equipment for the design of optical networks is an urgent task at present. The subject of this study is the process of selecting optical line terminals, which is associated with the evaluation of possible options by a set of indicators. The OLT (optical line terminal) in PON technology implements the function of organizing subscriber lines and is also a node equipment - an L4 switch that combines the functions of routing (IP), traffic fragmentation (VLAN), switching (MAC), quality of service (QoS), and some necessary network service functions. The optimal structuring of PON access networks demands a judicious selection of software and hardware, guided by their tactical and technical characteristics, in view of the substantial information load they entail. One of the effective approaches to solving such problems is the use of MCDM (Multiple Criteria Decision Making) methods. Purpose: to construct a TOPSIS model of the optimal choice of optical linear terminals in the conditions of unclear information for different cases of aggregation of evaluations of decision makers. Task: to formalize the process of selecting optical linear terminals; develop a multi-criteria mathematical model for the effective selection of optical line terminals. Methods used in the study: The fuzzy TOPSIS method, four methods of aggregating the opinions of decision makers. The following results were obtained. Alternatives and criteria for their evaluation are defined. On the basis of interviews with decision makers, evaluations of the degree of importance of the criteria and alternatives to the criteria were determined. Linguistic changes were used to describe decision-makers’ evaluations, which were interpreted as triangular fuzzy numbers. During this study, four methods of aggregating the evaluations of decision makers were used. A fuzzy TOPSIS model for selecting an optical line terminal is constructed. The ranking of the selected optical line terminals is obtained and the best alternative is determined. The results of modeling with different methods of aggregating assessments of decision makers are compared. Conclusions. The use of the Fuzzy TOPSIS method for optimal selection of optical linear terminals is proposed. The influence of the methods of aggregation of evaluations of decision-makers is analyzed.

Wavelength division multiplexing visible light communication with wide incident angle enabled by perovskite quantum dots

In this paper, a wavelength division multiplexing (WDM) visible light communication (VLC) system based on the perovskite quantum dots (QDs) with two different fluorescence wavelengths is demonstrated. This system consists of a transmitter, free space channel and a receiver. The NRZ-OOK (non-return-zero on-off-keying) signals are transmitted in this channel to achieve WDM visible light communication at a transmission distance of 60 cm, with a maximum transmission capacity of 100 Mbps in the field of view of 80°. In addition, computational temporal ghost imaging (CTGI) algorithm is used to reduce the bit error rate (BER) of the received signals and improve maximum transmission angle to 120°. The proposed WDM system paves the way for visible light communication in free space.

A novel dual polarization multiplexing RoF system integrating optical fiber and FSO channel with AMI downlink signals

Using dual polarization multiplexing alternate mark inversion (AMI) downlink signals, a novel radio over fiber (RoF) system integrating optical fiber and FSO channel is designed to adapt to applications in mountainous areas and other complex terrain areas. Optical heterodyne technology and self-mixing homodyne detection method are used to realize high sensitivity detection of the received signals after 25.1 km channel (including 1 km single-mode fiber and 100 m free space link) transmission. Moreover, polarization multiplexing technology is introduced to exponentially increase the transmission capacity of downlink signals. This scheme not only can be compatible with traditional optical fiber transmission systems, but also support the wireless optical access application of millimeter wave signals in RoF systems.

Optimal Configuration of Wind–Solar–Thermal-Storage Power Energy Based on Dynamic Inertia Weight Chaotic Particle Swarm

The proposed approach involves a method of joint optimization configuration for wind–solar–thermal-storage (WSTS) power energy bases utilizing a dynamic inertia weight chaotic particle swarm optimization (DIWCPSO) algorithm. The power generated from the combination of wind and solar energy is analyzed quantitatively by using the average complementarity index (ACI) to determine the optimal ratio of wind and solar installations. We constructed a multi-objective optimization configuration model for the WSTS power generation systems, considering the equivalent annual income and the optimal energy consumption level as objective functions of the system. We solved the model using the chaotic particle swarm optimization algorithm with linearly decreasing dynamic inertia weight. To validate the effectiveness of the proposed approach, we conducted a simulation using the 2030 power energy base planning data of a particular region in Inner Mongolia. The results demonstrate that the proposed method significantly improves the annual income, enhances the consumption of wind–solar energy, and boosts the power transmission capacity of the system.

A risk-aware and second-order cone programming model for wind expansion planning considering correlated uncertainties using the copula method

Integration of large-scale renewable energy sources (RESs) into existing power grids is challenging for power system operators and planners due to the intermittent and uncertain characteristics of RESs and the limitation of transmission capacity. This paper presents a new risk-based framework to obtain the optimal placement and sizing of wind farms in the bulk power system considering the impact of mutual correlation between wind farms’ power productions in different candidate buses. In this regard, a second-order cone programming (SOCP) optimization problem is developed to minimize the total expected social cost including the operation cost of conventional generators, wind curtailment cost, and the investment cost of newly installed wind farms. In the proposed model, the correlated uncertainties of wind power production are incorporated using the copula method. Also, the conditional value-at-risk (CVaR) measure is utilized to manage the risk of the model associated with uncertainties. The proposed planning model is then implemented into the Garver 6-bus and IEEE 118-bus test systems. Given the results, employing SOCP-based AC OPF in the presented planning model results in a precise solution, demonstrating an 87% reduction in running time. Moreover, the numerical results illustrate that by considering the correlation between wind farms’ power production and reducing the risk parameter, there is a significant increase in the installed capacity of wind farms.

Modelling flexibility requirements in deep decarbonisation scenarios: The role of conventional flexibility and sector coupling options in the European 2050 energy system

Russia's invasion of Ukraine has reaffirmed the importance of scaling up renewable energy to decarbonise Europe's economy while rapidly reducing its exposure to foreign fossil fuel suppliers. Therefore, the question of sources of flexibility to support a fully decarbonised European energy system is becoming even more critical in light of a renewable-dominated energy system. We developed and used a Pan-European energy system model to systematically assess and quantify sources of flexibility to meet deep decarbonisation targets. The electricity supply sector and electricity-based end-use technologies are crucial in achieving deep decarbonisation. Other low-carbon energy sources like biomethane, hydrogen, synthetic e-fuels, and bioenergy with carbon capture and storage will also play a role. To support a fully decarbonised European energy system by 2050, both temporal and spatial flexibility will be needed. Spatial flexibility, achieved through investments in national electricity networks and cross-border interconnections, is crucial to support the aggressive roll-out of variable renewable energy sources. Cross-border trade in electricity is expected to increase, and in deep decarbonisation scenarios, the electricity transmission capacity will be larger than that of natural gas. Hydrogen storage and green hydrogen production will play a key role in providing traditional inter-seasonal flexibility, and intraday flexibility will be provided by a combination of electrical energy storage, hydrogen-based storage solutions (e.g., liquid H2 and pressurised storage), and hybrid heat pumps. Hydrogen networks and storage will become more critical as we move towards the highest decarbonisation scenario. Still, the need for natural gas networks and storage will decrease substantially.

Multifrequency and Multimode Topological Waveguides in a Stampfli‐Triangle Photonic Crystal with Large Valley Chern Numbers

AbstractThe multifrequency quantum valley Hall effect (QVHE) has been realized to significantly improve the transmission capacity of topological waveguides, and the multimode QVHE with a large valley Chern number has been realized to increase the mode density of topological waveguides. However, multifrequency and multimode QVHEs have not been realized simultaneously. In this work, using tight‐binding model calculations and numerical simulations, a valley photonic crystal (VPC) consisting of a Stampfli‐triangle photonic crystal is constructed, and its multiple degeneracies in the low‐frequency and high‐frequency bands split simultaneously to realize the QVHE with multiple topological edge states (TESs). The multifrequency and multimode topological transmission with two low‐frequency modes and four high‐frequency modes is realized by means of simulations and experiments through a Z‐shaped waveguide constructed using two VPCs with opposite valley Chern numbers to prove the realization of a large valley Chern number in the two frequency bands. The two low‐frequency modes are successfully distinguished with position‐dependent selective excitations, which experimentally demonstrate the occurrence of a large valley Chern number. A frequency‐dependent multimode beam splitter is theoretically proposed for high‐performance integrated photonic device applications. These results provide new ideas for high‐efficiency and high‐capacity optical transmission and communication devices and their integration; furthermore, they broaden the application range of TESs.

Coordinated integration of wind energy in microgrids: A dual strategy approach leveraging dynamic thermal line rating and electric vehicle scheduling

As the world shifts towards sustainable energy, integrating wind energy as a key renewable resource is crucial, despite the challenge of its intermittent output. This paper proposes an integrated approach to enhance wind energy utilization within microgrids, introducing a novel synergy of Dynamic Thermal Line Rating (DTLR) and Electric Vehicle (EV) scheduling. This synergy dynamically adjusts power transmission capacities and harnesses EVs as mobile energy storage units. Notably, case study simulations reveal that compared to other approaches, our proposed solution reduces total operational costs by 24.6% (STLR only) and 11.6% (STLR+EV), and increases wind power absorption by 41.7% (STLR only) and 12.1% (STLR+EV). This marks a significant stride towards sustainable microgrid operation amidst renewable energy integration challenges.

Research on Knowledge Graph Construction and Semantic Representation of Low Earth Orbit Satellite Spectrum Sensing Data

The growth of frequency-usage devices has made the electromagnetic spectrum posture complex, resulting in an urgent demand for frequency-usage posture cognition. However, the sensing of space-based platforms is limited by the transmission capacity of the satellite-to-ground link and the satellite processing capacity, which makes on-satellite data analysis and posture generation lack the efficient means. Facing the above issues, an idea of a knowledge graph construction and semantic representation for low Earth orbit (LEO) satellite spectrum sensing data is designed in this paper. In the designed construction process, technologies such as knowledge extraction, ontology construction, knowledge fusion and knowledge visualization are utilized to efficiently analyze on-satellite sensing data. Moreover, the constructed spectrum knowledge graph can be applied in the analysis and prediction of frequency-usage behavior and intelligent spectrum management, which exhibits the effectiveness of the spectrum knowledge graph. Finally, the further development of the spectrum knowledge graph is foreseen.

An overview of 6G wireless systems

With the demand of low latency communication explodes, the inherent limitations of the fifth generation communication is constantly exposed to the public. Such 5G shortcomings are spurring worldwide activities focused on defining the next-generation 6G wireless communication system. So the paper offers an overview of 6G wireless systems based on existing literature and statistical data. The paper concentrate on the driving forces in the development of 6G. In the meanwhile, the paper presents some potential application scenarios in the future. In the last section, the paper points out some challenges that are most likely to encounter in the coming development of 6G. Based on current prospect of 6G, it is likely that 6G features low latency and high efficiency and has 100 times better transmission capacity than 5G. The future applications are holographic telecommunications, mutual interaction of emotional thinking, and digital twinning. In conclusion, integrated with different technologies like AI,Terahertz Communications, and blockchain, 6G features many advantages and will permeate into peoples daily lives.

Imaging the Vesicular Acetylcholine Transporter in Schizophrenia: A Positron Emission Tomography Study Using [18F]-VAT

BackgroundDespite longstanding interest in the central cholinergic system in schizophrenia (SCZ), cholinergic imaging studies with patients have been limited to receptors. Here, we conducted a proof-of-concept positron emission tomography study using [18F]-VAT, a new radiotracer that targets the vesicular acetylcholine transporter as a proxy measure of acetylcholine transmission capacity, in patients with SCZ and explored relationships of vesicular acetylcholine transporter with clinical symptoms and cognition. MethodsA total of 18 adult patients with SCZ or schizoaffective disorder (the SCZ group) and 14 healthy control participants underwent a positron emission tomography scan with [18F]-VAT. Distribution volume (VT) for [18F]-VAT was derived for each region of interest, and group differences in VT were assessed with 2-sample t tests. Functional significance was explored through correlations between VT and scores on the Positive and Negative Syndrome Scale and a computerized neurocognitive battery (PennCNB). ResultsNo group differences in [18F]-VAT VT were observed. However, within the SCZ group, psychosis symptom severity was positively associated with VT in multiple regions of interest, with the strongest effects in the hippocampus, thalamus, midbrain, cerebellum, and cortex. In addition, in the SCZ group, working memory performance was negatively associated with VT in the substantia innominata and several cortical regions of interest including the dorsolateral prefrontal cortex. ConclusionsIn this initial study, the severity of 2 important features of SCZ—psychosis and working memory deficit—was strongly associated with [18F]-VAT VT in several cortical and subcortical regions. These correlations provide preliminary evidence of cholinergic activity involvement in SCZ and, if replicated in larger samples, could lead to a more complete mechanistic understanding of psychosis and cognitive deficits in SCZ and the development of therapeutic targets.

Research on relay protection technology of high temperature superconducting cable system

High-temperature superconducting cables have many advantages such as low line loss, large transmission capacity, small space occupation, and environmental friendliness, which provide a highly efficient, compact, reliable, and green way of power transmission for power grids, and have great potential for application in large-capacity power transmission and urban power grid expansion and reconstruction. However, high-temperature superconducting cables have a complex structure, which is quite different from traditional cable lines in terms of operating conditions and fault mechanisms, and the requirements for the secondary system are also more stringent. Relying on the project of China Power Grid, “Research and Demonstration Application of Superconducting Transmission Technology in Urban Distribution Networks”, the thesis carries out an in-depth research on relay protection technology adapted to the access of high-temperature superconducting cables.

Photonic MMW Generation Using PM-DPMZM for Full Duplex 32×10 Gbps RoF-WDM System

Abstract This paper presents a study of a 32×10 Gbps Radio over Fiber and Wavelength Division Multiplexing (RoF-WDM) full-duplex system that uses Phase Modulators and a Dual-Port Mach-Zehnder Modulator (PMs-DPMZM) for bidirectional data transfer. The system employs Millimeter-Wave (MMW) signaling over optical fiber and focuses on selecting a technology that provides high transmission capacity per wavelength, improved spectral efficiency, and resistance against optical transmission impairments. The proposed method was validated using simulation results to confirm the efficiency of the proposed system in generating a 40 GHz signal and efficiently detecting and modulating the RF signals. The results demonstrate that the system exhibits strong resistance against dispersion, non-linear effects, and noise, delivering satisfactory performance for distances of up to 220 km. By analyzing the input power, the paper establishes a relationship between input power and signal quality, revealing that an optimal power of 0 dBm leads to an improved Quality Factor (QF) and reduced transmission errors. Furthermore, the evaluation of received optical power indicates the power level required to maintain an acceptable error rate, approximately -20.9690 dBm for downstream data transfer and -20.7245 dBm for upstream data transfer at the BER limit. The simulation performance also demonstrates the transmission efficiency achieved through a high Polarization Mode Dispersion (PMD) coefficient of up to 0.8. The analytical calculations conducted in this work provide valuable insights for optimizing and enhancing the performance of RoF-WDM networks.