Performance Of Communication Link Research Articles

Corrective Evaluation of Response Capabilities of Flexible Demand-Side Resources Considering Communication Delay in Smart Grids

With the gradual increase in the proportion of new energy sources in the power grid, there is an urgent need for more flexible resources to participate in short-term regulation. The impact of communication network channel quality will continue to magnify, and factors such as communication latency may directly affect the efficiency and effectiveness of resource regulation. In this context of a large number of flexible demand-side resources accessing the grid, this article proposes a bidirectional channel delay measurement method based on MQTT (Message Queuing Telemetry Transport). It can effectively evaluate the real-time performance of communication links, considering that resources mainly access the grid through the public network. Subsequently, focusing on two typical types of resources on the demand side, namely, split air conditioners and central air conditioners, this article proposes an assessment method for correcting the response capabilities of air conditioning resources considering communication latency. Experimental simulations are conducted, and the results demonstrate that under given communication conditions, this method can more accurately estimate the response capability of air conditioners. This provides a basis for formulating more reasonable scheduling strategies, avoiding excessive or insufficient resource regulation caused by communication issues, and aiding the power grid in achieving precise scheduling.

Comparing the Performance of Optical Communication Links using G.652 and G.655 Fiber in Python Packages

This study investigates and compares the performance of a 10 Gbps optical communication link utilizing two prevalent single-mode fibers: G.652 and G.655. The analysis employs both theoretical calculations and Python-based simulations to assess the effectiveness of each fiber type in this high-speed transmission scenario. With the ever-growing demand for bandwidth in communication networks, 10 Gbps transmission systems are becoming increasingly commonplace. Single-mode fibers like G.652 and G.655 play a vital role in these systems, offering low signal attenuation for long-distance data transmission. However, each fiber type exhibits distinct dispersion characteristics, which can impact signal integrity over extended distances. This investigation adopts a two method for performance evaluation. Firstly, link power budget calculations are performed to determine the optical signal power before and after propagating through a 50-kilometer fiber span. The received power serves as the foundation for subsequent Q-factor and Bit Error Rate (BER) analysis. These calculations establish the theoretical limitations of the system based on well-defined formulas. Secondly, Python-based simulations are conducted to corroborate the theoretical findings and provide a more comprehensive performance assessment. This approach leverages the capabilities of two prominent Python packages: Opticomlib and OpticommPy. Opticomlib excels at analyzing the behavior of individual optical pulses within the system, enabling an understanding of the signal propagation. On the other hand, OpticommPy specializes in parameter sweep analysis, allowing for the investigation of how critical parameters like received power influence the Q-factor. By combining these functionalities, the simulations provide a detailed picture of the system's performance under various conditions. The calculated BER and Q-factor values for both G.652 and G.655 fiber links surpass the industry-accepted performance standards. These results demonstrate the effectiveness of using Python-based tools for comprehensive performance analysis of optical communication systems. However, it's important to note that slight discrepancies exist between the calculated and simulated results.

Propagation of auto-focusing hypergeometric Gaussian beams along a slant path in oceanic turbulence

Compared to horizontal transmission, the oceanic dissipation rate and temperature-salinity distribution ratio are no longer constant but vary with depth, imposing greater complexity on oceanic turbulence when beams propagate through a slant path and resulting in more limitations on the performance of underwater wireless optical communication (UWOC) links. This study focuses on investigating the performance, especially the auto-focusing characteristic, of auto-focusing hypergeometric Gaussian (AHGG) beams propagating along slant paths in oceanic turbulence. We theoretically derive the spatial coherence radius and the relative probability of the orbital angular momentum (OAM) mode for AHGG beams passing through such links. Numerical simulations reveal that AHGG beams exhibit superior propagation performance compared to hypergeometric Gaussian beams. Lower beam orders and OAM numbers contribute to improved performance, while careful selection of auto-focusing length can tangibly enhance detection performance as well. Additionally, tidal velocities and wind speeds have nonnegligible effects on OAM signal probability. Our results further demonstrate that surface buoyancy flux, temperature gradients, and waterside friction velocity significantly affect beam transmission under varying wind conditions. These findings, particularly controlling the auto-focusing length of AHGG beams to match the transmission distance, provide valuable insights for enhancing the quality of UWOC links.

Impact of Motion Characteristics of Airborne Platforms on the Performance of Space Laser Communication Links

Impact of Motion Characteristics of Airborne Platforms on the Performance of Space Laser Communication Links

The Design and Implementation of a Phased Antenna Array System for LEO Satellite Communications.

LEO satellite constellations can provide a viable alternative to expand connectivity to remote, isolated geographical areas and complement existing IoT terrestrial communication infrastructures. This paper aims to improve LEO satellite communications by implementing a new phased antenna array system that can significantly improve the radio communication link's performance. By adjusting the progressive phase shift to each element of the antenna array system, the direction of the main radiation lobe of the phased antenna array system can be controlled with accuracy. As far as we know, it is the first time that a four-element, three-quarter wavelength phased antenna array system has been successfully realized with the intention of being optimized for implementation in LEO IoT satellite reception systems. The proposed system's high level of performance is confirmed by the measurements, which indicate effective control of the main radiation lobe orientation. The numerical analysis shows a maximum gain close to 12 dBi for about 42° elevation, a Half Power Beamwidth (HPBW) of 32° in the vertical plane, and 80° in the azimuth plane. The experimental measurement results at various main lobe orientation angles revealed an HPBW ranging from 76° to 87° in the azimuth plane and a maximum Front-to-Back ratio (F/B) of 14.5 dB.

Application of multi-source remote sensing technology in UAV communication control system

Abstract Unmanned aerial vehicles (UAVs) are crucial in various sectors but face challenges in communication reliability. This paper introduces a cutting-edge UAV communication control system, designed using time-series synthetic aperture radar interferometry (InSAR) technology and support vector machine (SVM) classification. Our findings reveal exceptional communication link performance across multiple flight scenarios, notably achieving a bit error rate (BER) of 0.001% in cruising mode. Additionally, the system demonstrated remarkable reception sensitivity, closely aligning with theoretical predictions at −81.1 dBm. This innovative approach utilizes multi-source remote sensing to significantly enhance UAV communication, offering a novel strategy for addressing UAV communication dilemmas.

Generation and free-space transmission characterization of bottle vortex beam

Vortex beams carrying orbital angular momentum (OAM) with the doughnut-shaped intensity distribution can be employed in free-space optical (FSO) communication links to circumvent obstructions. However, the size of the receiver aperture is proportional to the size of obstructions, which seriously constrains the application of OAM beams in this scenario. In this paper, we propose a method to generate bottle vortex beams (BVBs) with a parabolic trajectory by manipulating the radial phase distribution of conventional OAM beams. Meanwhile, the trajectory of BVBs generated are highly compatible with the predesigned trajectory by using this method. Moreover, we evaluate the free-space transmission performance of BVBs under atmospheric turbulence and limited receiving aperture. The results show that BVBs have better OAM FSO communication link performance compared with conventional OAM beams and Bessel beams. In addition, the performance of the BVBs circumventing obstructions is further investigated. The simulation results show that when setting the atmospheric turbulence strength D/r0 = 2 and the obstruction size of 40 mm, the average received optical power of the BVBs captured by a limited receiving aperture diameter (d = 40 mm) is improved about 7 dB and 3 dB compared to conventional OAM beams and Bessel beams, respectively.

Performance analysis of underwater vertical wireless optical communication links using selection combining.

In this paper, we have investigated the performance of underwater vertical wireless optical communication (UVWOC) links employing on-off key modulation for selection combining based receive diversity schemes in the presence of underwater turbulence, pointing errors, and attenuation losses. Due to variations in temperature and salinity along the ocean's depth, turbulence-induced fading affects the performance of the underwater vertical wireless optical link. The vertical link of the underwater medium influenced by a strong turbulence regime is modeled using cascaded gamma-gamma distribution considering multiple non-identical layers along with attenuation losses and pointing errors. We have derived closed-form expressions for the average bit error rate (BER) and outage probability (OP) for the link employing multiple detectors at the receiving end. The accuracy of all of the closed-form expressions derived in this paper has been validated using Monte Carlo simulations.

Image transmission performance analysis through free space optical communication link using coherent QPSK modulation under various environmental conditions

AbstractFree space optics (FSO) technology has been used recently in many applications due to its various advantages such as high bandwidth, easy deployment, high security, free installation license and immunity to electromagnetic interference. However, this type of communication is vulnerable to meteorological conditions such as rain, haze and fog which significantly degrade the system's efficiency. To enhance the effectiveness of the FSO systems, Quadrature Phase Shift Keying (QPSK) modulation based on coherent detection constitutes a promising technique for achieving high spectral efficiency and long‐distance FSO links with the characteristics of low‐cost implementation and simple design. This work aims to investigate the performance of FSO communication links on image transmission under the presence of atmospheric attenuations. A comparative study has been made using QPSK modulation scheme and on–off‐keying (OOK) modulation scheme to estimate the maximum range that was used to recover an RGB transmitted image over an FSO link under different meteorological weathers. The obtained results clearly show that the quality of the received image has degraded significantly during transmission through free space yielding to limit the propagation range. Moreover, the proposed FSO communication system performs well when using QPSK modulation rather than OOK modulation in different environmental conditions. Thus, to improve the quality of the received image under adverse fog weather condition, high power and small beam divergence angle have been suggested to increase system's performance. The proposed solution increases the communication range of the FSO link by 230 m and 100 m for moderate and heavy fog, respectively.

Adaptive LDPC coded high data rate based IR-UWB combined with VMIMO system for vehicular communication links

The automotive industry is developing significantly with the evolution of vehicular networks, intelligent transportation systems, and autonomous cars. These technologies are made achievable by recent advances in software, hardware, and communication systems, along with various applications and standardization efforts. On the other side, many impairments have existed due to these evolving, limiting the process of vehicular networks. So, this paper proposes an implementation of adaptive LDPC-coded, high data rate-based Impulse Radio-Ultra Wide Band (IR-UWB) combined with Virtual Multiple Input Multiple Output (VMIMO) systems for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) wireless communications. Furthermore, they are merged with orthogonal pulse shaping using a modified Hermite pulse. Besides, the paper compares Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) detection techniques. To enhance and mitigate the existing impairments facing the vehicular networks. The proposed system’s performance is evaluated using both techniques, utilizing Bit Error Rate (BER), processing time, and resultant throughput analysis for both channel models. The simulation results include Non-Line of Sight (NLoS) and Line of Sight (LoS) scenarios for both channel models. Moreover, the simulation considers the effect of path loss and noise on the transmitted signal. In addition, the recent LDPC decoding algorithm termed “Modified Implementation Efficient Reliability Ratio Weighted Bit Flipping” (MIERRWBF) is evaluated through all latter channel models. At last, a novel adaptive LDPC decoder is proposed to further enhance the performance of all vehicular communication links under study. Consequently, the paper proposed an integrated adaptive LDPC-coded high data rate communication system to enhance vehicular communications using VMIMO mixed with modified Hermite orthogonal pulse shaping and deploying the MMSE recommended detection technique.

A New Reference Sample for High-Frequency Multipactor Testing

Multipactor (MP) is a high-power effect severely limiting the performance of satellite communication links. A reference sample is normally used in the experimental setups for MP testing in order to verify its correct operation. However, the low gaps required for high frequencies jeopardize the manufacturability of the devices traditionally used for this purpose. A new reference sample, based on a stepped-impedance resonator (SIR), is proposed in this letter. The key design considerations are also outlined. A prototype operating between 17 and 18 GHz has been manufactured and tested, proving the novel structure allows higher gaps, and is, thus, suitable for higher frequency bands.

Improved 300 GHz FSO communication link performance using hybrid OQPSK/AM modulation with predistortion under extreme weather conditions

Improved 300 GHz FSO communication link performance using hybrid OQPSK/AM modulation with predistortion under extreme weather conditions

Outage probability analysis of maritime FSO links

In this paper, the outage performance of the maritime free-space optical (FSO) communication system is analyzed, and a new maritime FSO link configuration is presented. The channel model for maritime FSO link includes the combined effect of turbulence, pointing error, angle-of-arrival (AOA) fluctuations, and attenuation. While the maritime turbulence channel is modeled by lognormal distribution, pointing error and AOA fluctuations are assumed to be Beckmann and Rayleigh distributed, respectively. The turbulence power spectrum is considered to present the Kolmogorov characteristics, and the Rytov variance of a propagating Gaussian beam in maritime environment is obtained. The probability density function (PDF), cumulative distribution function (CDF), and outage probability of the maritime communication channel are obtained analytically. The outage performance of a maritime communication link is given depending on various parameters of the maritime environment, the Gaussian beam, and the (FSO) communication system.

Analysis of Optical Wireless Communication Links in Turbulent Underwater Channels With Wide Range of Water Parameters

In this study, the performance of underwater optical wireless communication links is investigated by taking into account turbulence, absorption and scattering effects. Weak turbulent channel is modeled using log-normal distribution while moderate and strong turbulence channels are modeled using gamma-gamma distribution. Rytov variance of Gaussian beam is derived analytically for oceanic turbulence optical power spectrum. Subsequently, scintillation index is calculated using the computed Rytov variance. Moreover, the closed-form expression of bit-error-rate (BER) for underwater wireless optical communication (UWOC) systems using intensity-modulated/direct detection (IM/DD) implementation and on-off-keying (OOK) modulation scheme is obtained. Results show that the performance of wireless optical communication link between two platforms in underwater medium is degraded significantly due to turbulence, absorption and scattering. In fact, as the turbulence level increases, its effect becomes quantitatively comparable to those of absorption and scattering effects. The variation of both scintillation index and BER performance are presented for various underwater medium and communication system parameters, such as chlorophyll concentration, average temperature, average salinity concentration, temperature and dissipation rates, wavelength, link length and receiver aperture size. Optical network and internet of underwater things (IoUT) applications, which are growing day by day and requiring high data rates, will benefit from the results of this study.

Statistical channel modeling of intensity fluctuations in a turbulent underwater wireless optical communication system

Subject of study. The statistical modeling of received intensity fluctuations due to temperature-induced turbulence and the random presence of air bubbles in an underwater wireless optical communication channel is presented. Aim of study. Temperature-induced turbulence and air bubbles induce severe intensity fluctuations in the received optical signal, which degrade the underwater wireless optical communication link performance. Method. Therefore, to characterize the turbulent water channel, an experimental setup has been designed in the laboratory that considers uniform and gradient-based temperature variations along with variable-sized bubble populations. To estimate the effect of these random variations in the water channel, a statistical approach has been followed, which characterizes the nature of the recorded observations. Main results. It is observed that the behavior of random irradiance fluctuations due to uniform and gradient-based temperature variations in the underwater wireless optical communication link follows a single-lobe Gaussian distribution. Moreover, with the incorporation of air bubbles, the received irradiance fluctuations no longer follow a single-lobe Gaussian distribution but follow a multi-lobe Gaussian distribution, i.e., the Gaussian mixture model, which is the weighted sum of the Gaussian distribution. The accuracy of the proposed underwater wireless optical communication link models is verified by conducting the goodness of fit test; the observed confidence interval of 95% authenticates the proposed model. Also, the performance of the Gaussian-mixture-model-based underwater wireless optical communication link has been evaluated in terms of bit error rate, and the acceptable bit error rate levels between 1014 and 1010 have been observed. The proposed underwater wireless optical communication with Gaussian mixture model completely depicts thermally uniform, gradient-based nonuniform, and variable air bubble populations in the ocean. Practical significance. The Gaussian mixture model can further be utilized by the researchers to estimate numerous performance parameters of the turbulent underwater wireless optical communication links using advanced modulation schemes and diversity techniques and paves a valuable way to address the future aspects of research in this area.

Performance Analysis of MIMO-mQAM System with Pointing Errors and Beam Spreading in Underwater Málaga Turbulence Channel

Both the long-term beam spreading caused by ocean turbulence and the pointing errors induced by the jitter of transmitters and receivers degrade the performance of underwater wireless optical communication (UWOC) links. To effectively alleviate their effects, an in-depth study was carried out over the Málaga turbulence channel with pointing errors and beam spreading in multiple-input and multiple-output (MIMO) UWOC. First, we analyzed the long-term beam spreading and the received light power for the finite receiving aperture in the presence of pointing error displacements. Based on this, the relationship between beam spreading, pointing errors, and signal power was established. Second, the approximate expressions of the average bit error rate (BER) and the communication outage probability were derived theoretically for this MIMO system using maximal-ratio combining (MRC) diversity. Third, the effects of the pointing errors on the coding and the diversity gains were explored for the MIMO links. Finally, using the observed ocean data from the Global Ocean Argo gridded dataset, we numerically verified the combined effects of ocean turbulence strength, beam spreading, and pointing errors on the average BER and outage probability of this system. These results also proved that adjusting the size of the receiving aperture or the order of the multiple quadrature amplitude modulation (mQAM) could effectively mitigate their effects.

Satellite vibration effects on communication quality of OISN system

Abstract Over space optical communications are considered as the critical technology for high-bandwidth, high-speed, and large-capacity communications. Indeed, the laser wavelength’s narrow beam divergence requires a precise beam pointing at both ends of the optical link. The precise beam pointing makes the laser beam pointing to or from a moving object is one of the most challenging processes for optical space communications. In this work, the effect of the pointing error due to satellite platform vibration over the performance of the laser communication link of the optical inter satellite network (OISN) system in terms of the quality factor is investigated. Indeed, an optical communication system has been built using the OptiSystem program to simulate the link between satellites in space for the OISN system. In addition, the proposed system shows by simulation the optimal parameters’ values required for the design of the optical communication link between satellites of the OISN system. Moreover, the effect of pointing error due to the platform vibration on the performance of the OISN system is investigated for different scenarios of the pointing error (i.e., no pointing error; one side of the link with pointing error, and two sides of the link with pointing error). The simulation shows that, first, the optimal parameters that can be used for the optical communication link between satellites of the OISN system in terms of the laser wavelength; laser power; optical modulation scheme; optical telescope aperture diameter; and telescope optical efficiency. In addition, the simulation shows that existing pointing error due to vibration at one side of the optical link leads to degradation of the performance of the OISN system in terms of the quality factor for different laser beam power; distances between satellites; telescope diameters; and telescope efficiencies. Moreover, existing pointing errors at the two sides of the optical link lead to rapid degradation of the considered OISN system performance even with the increase of the laser power or telescope diameter, which tend to compensate for its effect initially and then quit.

Low Latency Reliable Data Sharing Mechanism for UAV Swarm Missions

The use of Unmanned Aerial Vehicle (UAV) swarms is increasing in many commercial applications as well as military applications (such as reconnaissance missions, search and rescue missions). Autonomous UAV swarm systems rely on multi-node interhost communication, which is used in coordination for complex tasks. Reliability and low latency in data transfer play an important role in the maintenance of UAV coordination for these tasks. In these applications, the control of UAVs is performed by autonomous software and any failure in data reception may have catastrophic consequences. On the other hand, there are lots of factors that affect communication link performance such as path loss, interference, etc. in communication technology (WIFI, 5G, etc.), transport layer protocol, network topology, and so on. Therefore, the necessity of reliable and low latency data sharing mechanisms among UAVs comes into prominence gradually. This paper examines available middleware solutions, transport layer protocols, and data serialization formats. Based on evaluation results, this research proposes a middleware concept for mobile wireless networks like UAV swarm systems.

High-sensitivity multi-channel DPSK system with real-time phase lock controller for free-space optical communication

To overcome the power jitters in satellite-to-ground communications caused by atmospheric turbulence, a type of DPSK free-space communication system, assisted by a self-designed real-time phase lock controller, has been established. The system can effectively compensate for power swings in communication links and hence achieve high sensitivity. The wavelength division multiplexing technique is applied to a four-channel DPSK system to provide greater link capacity. With the data rate of a single channel as 2.5 Gbps and unencoded BER as 1 × 10–3, reception sensitivity has been obtained at −53.58 dBm (13.69 photons/bit), −53.59 dBm (13.66 photons/bit), −53.61 dBm (13.59 photons/bit), and −53.63 dBm (13.53 photons/bit) for each independent channel, respectively. The gap between our sensitivity result and the theoretical limit has narrowed to about −3.5 dB. Simultaneously, the DPSK receiver, with our self-designed phase lock controller, has stabilized reception of optical power fluctuations that range from 0 to 40 dB. Additionally, the impact of a four-wave mixing effect on multi-channel system performance has been investigated in detail. Our experimental results present a novel solution for the superior performance of free-space communication links.

Comprehensive experimental and statistical analysis of the effects of salinity gradient, temperature gradient, air bubbles on the performance of underwater wireless optical communication link

Salinity gradients (SGs), temperature gradients (TGs), and different-sized air bubbles affect the optical signal propagating in the UWOC link. These effects contribute to beam wandering, spot dancing, and intensity fluctuations in the received optical signal. In this paper, experimental analysis has been carried out to estimate the effect of SG, TG and air bubbles on the underwater optical signal. The beam wandering, mean and variance deviation, displacement of weighted centroid, the statistical distribution of received intensities and link outage probability have been estimated in this work. It has been found that the beam wandering effects follow a Gaussian mixture model (GMM). It is also observed that in the presence of air bubbles in the SG, the chances of link outage increase from 48% to 80% and it increases from 7% to 28% in the TG conditions. Furthermore, the experimental and theoretical modelled outage probabilities are in close agreement.