Transmission Channel Capacity Research Articles

NUMERICAL METHOD FOR CALCULATING THE LOCATIONS OF SAFETY SYSTEM REPEATERS ON TERRAIN WITH OBSTACLES

When deploying temporary technical security systems in the interests of ensuring public safety during mass events, quick-deployable sensors for detecting dangerous events are widely used: to monitor traffic flows and visitors, to detect fires, fights, aggressive behavior, dangerous abandoned objects and unmanned aerial vehicles. A number of important limitations, including geometric dimensions of the detector and repeater installation areas, the capacity of data transmission channels, the presence of restricted areas and the high speed of data transmission from modern sensors of dangerous events, show the need for rational location of repeaters. An iterative algorithm used to estimate placement locations provides an opportunity to find repeater installation points in order to ensure the transmission of high-speed monitoring information flows.

A Dynamic Load Increasing Method for 220 kV Overhead Transmission Lines and Application

With the continuous development of China’s economy, the demand for electricity in society is increasing year by year, and it is necessary to continuously strengthen the construction of transmission capacity. This article aims to develop a terminal monitoring device that can monitor the status of transmission lines and the environment, analyze the monitoring data of overhead line status and micrometeorological data, and, based on the prediction model of the current carrying capacity of transmission lines, fully tap the power supply potential of transmission lines, which is of great significance for improving the transmission capacity of transmission channels.

A Precise Calculation Method of Conductor Current Based on FEM

The demand for electricity in society is increasing. It is necessary to continuously strengthen the construction of transmission capacity. This article establishes a precise calculation method for the current carrying capacity of wires based on finite element analysis, taking into account the aluminum core diameter, steel core diameter, pitch diameter ratio, rotation angle, etc., which has higher calculation accuracy and is suitable for calculating the current carrying capacity in different meteorological environments. It is of great significance for fully tapping the power supply potential of transmission lines and improving the capacity of transmission channels.

Ultra‐Wideband Electrostrictive Mechanical Antenna

AbstractMechanical antennas based on piezoelectric materials can effectively reduce the size of long wave antennas down to 1/1000 of the wavelength (from km scale to mm level). However, the narrow bandwidth and weak field intensity seriously restrict its practical applications in transmission distance and channel capacity. Here, a mechanical antenna‐based electrostrictive effect of relaxor ferroelectric ceramic (PMN‐PT) is proposed to improve radiation capacity and achieve ultra‐wideband characteristics (10 kHz–1 MHz). Due to the ultra‐high dielectric constant at working temperature and the relationship between the strain and applied field intensity, the proposed antenna gets rid of the dependence on the poled materials and exhibits excellent communication properties beyond traditional mechanical antennas, which are experimentally demonstrated by a practical wireless communication system. Only using a single proposed mechanical antenna with 8 mm diameter and 3 mm thickness, the effective communication with a transmission distance of 200 m can be realized. This design offers a promising way of constructing mechanical antennas for long‐wave communication.

Joint Planning of Offshore Wind Power Storage and Transmission Considering Carbon Emission Reduction Benefits

There are two situations of transmission redundancy and transmission congestion when large-scale offshore wind farms send power out. The energy storage system can store the power blocked by wind power due to insufficient transmission capacity and release it in the period when the wind power output level is low. In this paper, a full-life-cycle cost model is established for energy storage, and a joint planning model for offshore wind power storage and transmission considering carbon emission reduction benefits is established, which integrates power grid transmission benefits, carbon emission reduction benefits, energy storage construction costs, transmission project construction costs and wind abandonment penalty costs. The channel construction and energy storage configuration scheme with the greatest net benefit can be obtained. The relationship between the transmission channel capacity setting and the energy storage parameter configuration under this model is studied, and the combined effect of transmission channel and energy storage system in improving the level of wind power transmission is analyzed. The sensitivity analysis of the influence of the optimal storage and transmission planning scheme of the offshore wind farms is carried out from the perspectives of transmission line engineering cost and transmission channel curve type.

Application scheme and performance analysis of free space optical communication technology in INMARSAT

Abstract In this study, we propose an application scheme of free space optical communication technology in INMARSAT, and propose a 1.12 Tbit/s coherent free-space optical (FSO) communication system based on wavelength division multiplexing (WDM) and polarization-multiplexing quadrature phase shift keying (PM-QPSK) modulation technology. Based on optisystem software platform, the spectrum, bit error rate (BER), received power, error vector magnitude (EVM), and receiver sensitivity of the edge and middle channels of the system are analyzed. The simulation results show that the transmission rate and channel capacity of INMARSAT communication system are greatly improved by selecting the channel spacing and transmission environment reasonably.

Assessing the integration potential of new energy in river basin clean energy corridors considering energy-power coupled complementary operation modes

Operating new energy (wind and solar) complementarily with the existing hydropower stations is a promising way for efficient accommodation of utility-scale new energy. China plans to build a batch of river basin hydro–wind–solar clean energy corridors (RBCECs) by integrating new energy into the existing large hydropower bases. This paper proposes a universal method to determine the effective complementary operation mode and the optimal capacity configuration of new energy for RBCECs. First, the energy–power coupled complementary operation modes are proposed to fully tap the hydropower flexibility, compensating the variable new energy. Then, an optimization model framework is constructed to determine the optimal capacity configuration of new energy for RBCECs; the model framework can simulate the 8760–hour–time–series operation of hydro–wind–solar hybrid system. Moreover, the proposed operation modes can be respectively plugged into the model framework to calculate the corresponding optimal capacity configuration of new energy for RBCECs. The Beipan RBCEC in China, is selected as a case study, and its effective complementary operation mode and the optimal capacity configuration of new energy are determined. Results also indicate that (1) integrating new energy into hydropower system will change the inter-seasonal distribution of water and electricity of the hydropower stations; (2) the ability of hydropower stations to compensate variable new energy will be affected by runoff; (3) the theoretical maximal integration potential of new energy in a RBCEC will be affected by the installed hydropower capacity, reservoir storage, and complementary operation modes; but the actual deployment level of the theoretical maximum integration potential will be affected by the capacity of power transmission channels.

Sub-terahertz (THz) antenna for Internet of Things and 6G Communication

Abstract Sub-terahertz (THz) technology is expected to deliver exceptional data rates for future sixth generation wireless communication systems especially for intelligent communication among devices falling under the Internet of Things (IoT) category. Moving from current 5G millimeter wave (mmW) technology towards THz spectrum will eventually provide unprecedented solutions that will guarantee higher transmission rates and channel capacity for any wireless communication system. With various electronic and wireless components working together to fulfill this promise, high gain antennas having compact profile is one such technology that will aid in achieving sub-THz communication while offering low path and power losses with reliable and fast data transfers. In this context, this work proposes a novel deformed patch antenna operating in the sub-THz spectrum i.e. at 300 GHz band. The proposed antenna is fed via a microstrip line following the proximity coupled feeding technique. Utilizing this technique provides a wide impedance bandwidth with a broadside radiation pattern having minimum side lobe levels of around −12 dB and a directivity of 10–15 dBi for the single and array elements respectively. The proposed design has a small footprint of 1.5 × 1.5 × 0.06 mm3 for the single element while the array element has dimensions of 6 × 5 × 0.06 mm3. Both the designs have been simulated in Computer Simulation Technology-Microwave Studio (CST-MWS) and the results verified via high-frequency structure simulator (HFSS) simulator. The results confirm the viability of the proposed designs to be potential candidates for future sixth generation and IoT based applications.

Simulation and experimental investigation of nonlinear effects in 5G fronthaul transmission system based on WDM-PON architecture

Wavelength-division multiplexing passive optical network (WDM-PON) is considered as a mainstream solution for 5G fronthaul transmission system to cope with the rapidly increasing bandwidth demand. In such a multi-wavelength system, nonlinear effects limit the achievable transmission distance and channel capacity. Therefore, in this paper, the impact of nonlinear effects on a multi-wavelength transmission system with 25 Gb/s/λ non-return-to-zero (NRZ) and a 200-GHz channel spacing over 25 km standard single-mode fiber (SSMF) is investigated through experiment and simulation. The effects of four-wavelength mixing (FWM) in O-band as well as cross-phase modulation (XPM) in C-band are both studied and discussed. Experiments are performed for 3- and 4-channel transmission cases, while 12-channel transmission is performed by simulation. The results show that in the O-band scenario, the FWM effect severely affects the performance of the channels near the zero-dispersion wavelength. Besides, the XPM products overlap the signal in the C-band, which also degrades the sensitivity. Based on these analyses, the nonlinear effects should be fully considered when planning wavelengths for 5G fronthaul transmission, including wavelength distribution and channel spacing selection.

Vanadium dioxide embedded frequency reconfigurable metasurface for multi-dimensional multiplexing of terahertz communication

Multi-dimensional multiplexing based on the broadband metasurface is a promising candidate for the next generation terahertz (THz) communication system, which has become a research focus for data transmission rate and channel capacity enhancement. This paper proposes a THz frequency-reconfigurable metasurface hybridized with vanadium dioxide (VO2) for communication multiplexing on both dimensions of orbital angular momentum and frequency. Theoretically, 4 × n channel (n can be any positive integer) orthogonal coaxial beams carrying different data flow can be simultaneously generated based on the proposed metasurface in the tunable operating frequency band. The simulation results verify that the THz incident waves can be converted into orthogonal coaxial beams with different topological charges or frequencies, propagating perpendicular to the metasurface, when eight-channel oblique incident plane waves with varying angles or at various frequencies are reflected by the metasurface. The multi-dimensional multiplexing can be achieved in the frequency range of 0.29–0.39 THz and 0.24–0.34 THz with the VO2 switching between its fully insulating and metallic state. The proposed metasurface is expected to enable multi-band and broadband applications and has significant potential in high-speed and high-capacity THz communication.

ВИСОКОЕФЕКТИВНИЙ ХВИЛЕВОДНИЙ ПОЛЯРИЗАТОР ДЛЯ СУПУТНИКОВИХ ІНФОРМАЦІЙНИХ СИСТЕМ

У сучасних супутникових інформаційних системах та безпровідних системах передачі даних широко використовують сигнали із коловими поляризаціями. Сигнали цього типу вимагають застосування спеціальних антенних систем із поляризаційним обробленням. Такий підхід дає можливість удвічі зекономити частотні ресурси, які є обмеженими. У результаті збільшується інформаційна ємність каналів передачі інформації в супутникових та інших інформаційних системах. Базовим елементом антенних систем із коловими поляризаціями є поляризатор. Такий пристрій здійснює перетворення електромагнітних хвиль із круговою поляризацією в лінійно поляризовані хвилі або навпаки. Використання поляризатора та ортомодового перетворювача в антенних системах забезпечує перетворення поляризації сигналів із одночасною передачею їх до розв’язаних хвилеводних каналів. Стаття містить результати аналізу та оптимізації нового високоефективного хвилеводного поляризатора для супутникових інформаційних систем. Конструкція розробленого поляризатора складається із хвилеводу квадратного перерізу з чотирма діафрагмами. Виконано оптимізацію поляризатора для його застосування в робочому діапазоні частот від 10,7 ГГц до 12,8 ГГц. Проаналізовано й оптимізовано фазові, поляризаційні характеристики та характеристики узгодження із застосуванням чисельного методу скінченного інтегрування. Розроблений хвилеводний поляризатор із чотирма діафрагмами забезпечує диференційний фазовий зсув 90° ± 3,5°, коефіцієнт стійної хвилі з напругою, меншою 1,24, коефіцієнт еліптичності, менший 0,53 дБ, кросполяризаційну розв’язку, вищу 30,3 дБ. Таким чином, створений новий поляризатор на основі квадратного хвилеводу з чотирма діафрагмами забезпечує якісну роботу в усьому робочому Ku-діапазоні частот 10,7–12,8 ГГц. Пристрій може широко використовуватися в сучасних антенних системах із поляризаційним обробленням сигналів у телекомунікаційних, радіолокаційних і супутникових інформаційних системах.

Хвилеводно-щілинний фідерний тракт антен з коловою поляризацією

Modern information systems use circularly polarized signals. Among them are tracking systems, remote sensing systems, satellite television systems. The use of circularly polarized signals in satellite communication systems allows to combat multipath propagation of signals in the environment, which reduces interference. By reflecting signals from different objects, they transform their polarization. This makes it possible to reduce signal distortions in the receiving device, which increases the information capacity of wireless data transmission channels. In satellite communications, multi-band horn antennas are widely used. The use of such devices allows transmission of signals with high power and reception of signals with low noise level. Such systems are used as powering a reflector antenna with a wide bandwidth. For such applications, a horn antenna device has been proposed in which signals can be excited that produce left-hand circularly polarized signals and right-hand circularly polarized signals. The proposed horn antenna was powered through a slot that was cut in a rectangular waveguide. Due to the 45º angle of the slot, the antenna can generate signals with double circular polarization. The proposed design can be used without polarizing devices, which must be developed separately. The developed design of the horn antenna at the operating frequency of 16 GHz provides a peak antenna gain of 24 dB for signals with right circular polarization and a peak value of a gain of 18 dB for signals with left circular polarization. The polarization isolation is greater than 12 dB. Moreover, at the operating frequency, the maximum value of the reflection coefficient takes on a value of –17 dB. Thus, the developed waveguide slot feed section for antennas with circular polarization provide rather good characteristics in a narrow frequency band.

Оптимізація розподілу потужностей мережевих каналів на основі алгоритму Орліна

The article proposes an algorithm for solving the problem of optimal distribution of the capacity of data transmission channels between providers and Internet users. A mathematical model of the problem of distribution of a limited homogeneous resource with transport-type constraints is formulated. A solution method based on Orlin's stream algorithm is considered. A practical application of the algorithm for solving a real distribution problem is proposed. The results of the capacity of the channels of the computer network are obtained with a perspective increase in the capacity of the connections represented by the intervals of the planned changes. An analysis of the solutions obtained with different number of switching servers was made, conclusions about the choice of the provider to meet the optimal information needs of users were made.

A Calculation Method of Available Transmission Capacity for Medium and Long-term Electricity Trading

In view of the fact that China’s power dispatching agencies and trading centers are relatively independent, but the medium and long-term power transactions need physical execution, which leads to higher requirements for transaction security boundary, this paper proposes a calculation method of available transmission capacity for medium and long-term power transactions, which calculates the available transmission capacity of transmission channels through probabilistic method to improve the enforceability of transaction results. Numerical simulation results also verify the effectiveness of the algorithm.

Research on dispersion compensation using avalanche photodiode and pin photodiode

With the growing demand for usage among Internet users, inventions related to increase in the capacity and bandwidth of transmission channels are more significant nowadays. This continuously growing demand can be fulfilled by using the optical fibre for transmission of signals instead of the wireless mode of transmission, due to the less non-linearity present in the optical fibre. As every available mode has its own shortcomings so does the optical fibre. It suffers from dispersion and other linearities when long-distance transmission is considered. Hence, the field of invention is associated with the compensation of dispersion in optical fibre communication at higher bit rates of 50–80 Gbps for longer distances of 120 km. After their compensation, comparison of two photodiodes, that is, pin diode and avalanche photodiode has been done at these distinct bit rates in order to achieve the best suited photodiode. After the complete analysis of simulations in terms of quality factor and bit error rate, it has been observed that at distinct bit rates of 50–80 Gbps, the simulation model using avalanche photodiode exhibits superior performance to that of the pin diode. The comparison results show that the performance of the avalanche photodiode is around 11% better than the pin diode.

Smart Waste Monitoring System as an Initiative to Develop a Digital Territory in Riobamba City

Digital territories focus on community transformation through sustainable development, saving resources in local governments, bridging the digital gap, and using technology to build smart infrastructure. This article presents the design and implementation of a smart system, called the Waste Treatment System (WTS), for controlling parameters of waste decomposition in the trash bins installed in Riobamba city (Ecuador). The prototype allows monitoring in real time both the amount of waste and the level of rottenness of garbage by means of the measurement of different parameters that indicate the characteristics of the leachates generated inside. The motivation of this work was to yield an efficient solution to urban waste treatment that optimizes resources in the collection process by providing real-time information to improve collection frequency vehicles and also reduce emissions by the decomposition of organic waste. The tests allowed assessing technical aspects such as the maximum coverage of wireless communication, the transmission channel capacity for each prototype, the data-processing requirements, and other more particular parameters such as the production of leachates due to the frequency of collection and the environmental conditions, which will be useful in future work on environmental impact.

Analysis of the Raman spectrum of high-power amplifiers of wireless communication systems

At present, the transfer of information is an integral part of technologies that are actively developing in the framework of the process called the Fourth Industrial Revolution. In this, space-satellite, satellite and other mobile wireless communication systems play an increasingly important role. Almost all of them include multiple access, which means a method of common resource division of the communication channel between subscribers (each mobile station has the ability to use a satellite retransmitter or the base station of a mobile wireless communication system to transmit its signals regardless of the operation of another station). Multiple-access communication systems are used for digital radio and television broadcasting in high-speed communication lines, in wireless local area networks, for data transmission in the microwave range, and also for communication with various mobile partners. In the radio transmitting and receiving paths of communication systems with multiple access, multiple signals are used (the sum of the power of the subscriber signals) with very complex types of digital envelope modulation, so they use wide working bands. With an increase in the quality of information transmission in mobile wireless communication systems, there are special requirements for powerful amplification systems (PAS) of receiving-transmitting tracts, which must have high efficiency and high output power, required bandwidth, network capacity, and linearity of message transmission channels. To achieve maximum efficiency in the PAS, the operating point of its amplifying element should be near the saturation region, on the main nonlinearity of the transfer characteristic. When multiple signals are introduced simultaneously into the PAS, it generates unfiltered intermodulation harmonics (IH). Intermodulation harmonics are formed due to the nonlinearity of the amplitude characteristics and the unevenness of phase-amplitude characteristics and due to the need to work with the highest efficiency of the PAS, which requires a shift of the operating point to the saturation thresholds of their amplifying elements. This, in turn, causes the appearance of IH. Since the harmonic oscillations IH actually represent noise for neighboring communication channels and are not theoretically filtered, an equalizer (otherwise an optimizer) of characteristics, is needed to reduce the level of these interferences in the output (Raman) spectrum of the PAS.

A Review of Broadband Low-Cost and High-Gain Low-Terahertz Antennas for Wireless Communications Applications

Low-terahertz (Low-THz, 100 GHz-1.0 THz) technology is expected to provide unprecedented data rates in future generations of wireless system such as the 6th generation (6G) mobile communication system. Increasing the carrier frequencies from millimeter wave to THz is a potential solution to guarantee the transmission rate and channel capacity. Due to the large transmission loss of Low-THz wave in free space, it is particularly urgent to design high-gain antennas to compensate the additional path loss, and to overcome the power limitation of Low-THz source. Recently, with the continuous updating and progress of additive manufacturing (AM) and 3D printing (3DP) technology, antennas with complicated structures can now be easily manufactured with high precision and low cost. In the first part, this paper demonstrates different approaches of recent development on wideband and high gain sub-millimeter-wave and Low-THz antennas as well as their fabrication technologies. In addition, the performances of the state-of-the-art wideband and high-gain antennas are presented. A comparison among these reported antennas is summarized and discussed. In the second part, one case study of a broadband high-gain antenna at 300 GHz is introduced, which is an all-metal model based on the Fabry–Perot cavity (FPC) theory. The proposed FPC antenna is very suitable for manufacturing using AM technology, which provides a low-cost, reliable solution for emerging THz applications.

Fiber Nonlinearity Mitigation in Single Carrier 400 G and 800 G Nyquist-WDM Systems

Fiber Kerr nonlinearity limits the achievable transmission distance and channel capacity of high speed optical communication systems. In this paper, we study the performance of C-band single carrier 400 G and 800 G 16-ary quadrature amplitude modulation (16 QAM) or 64-ary quadrature amplitude modulation (64 QAM) Nyquist wavelength division multiplexed (WDM) systems with emphasis on fiber nonlinearity and its mitigation. The nonlinearity mitigation methods of digital back-propagation (DBP) and coupled-equation digital back-propagation (CE-DBP) are discussed for single channel and multi-channel systems, respectively. The DBP algorithm is a general approach suitable for compensating intra-channel nonlinearity. The CE-DBP is an extension of the DBP, which can deal with both intra- and inter-channel nonlinearity by solving the coupled multi-channel Manakov equations. Based on the first order perturbation theory, we also analyze the application of Kalman filter (KF) to nonlinearity compensation, which utilizes correlation between adjacent symbols to compensate for Kerr nonlinearity. With numerical simulations, the performance of three nonlinearity equalization schemes of CE-DBP, DBP + KF, and CE-DBP + KF are compared. For nonlinearity mitigation in single carrier 400 G and 800 G WDM systems, the DBP + KF is more efficient than the CE-DBP considering five coupled channels. The CE-DBP + KF method has slightly better performance than the DBP + KF. However, the CE-DBP is quite complex due to multi-channel Manakov equation calculation, which demands broad-band joint detection with a single coherent receiver or several individual coherent receivers with time synchronization. In contrast, the DBP + KF only need the information of the target channel. We thus conclude that the DBP + KF is an attractive solution to mitigate fiber nonlinearity for single carrier 400 G and 800 G Nyquist-WDM systems. With the combination of the DBP and the KF, the transmission distance extensions are achieved as 12.5%, 14.3%, 22.6% and 28% for 400 G_64 QAM, 800 G_64 QAM, 400 G_16 QAM and 800 G_16 QAM WDM systems, respectively.

Achieving Full-Duplex Communication: Magnetless Parametric Circulators for Full-Duplex Communication Systems

In a crowded electromagnetic spectrum with ever-increasing demand for higher data rates to enable multimedia-rich applications and services, the efficient use of wireless resources becomes crucial. For this reason, full-duplex communication [1]-[4], which increases the capacity of transmission channels by operating the uplink and downlink simultaneously on the same frequency channel (see Figure 1), is returning to the spotlight after decades of being presumed impractical. This long-held assumption resulted mainly from the need for large isolation (IX) between the transmit (Tx) and receive (Rx) nodes [also known as self-interference cancellation (SIC)], which typically needs to be greater than 100 dB, a challenging task that requires several innovations at the network and physical layer levels.