Improve Transmission Efficiency Research Articles

SDN-based dynamic multi-path routing strategy for satellite networks

Software Defined Network (SDN) is a new network architecture which is efficient, dynamic, controllable and adaptable. It is suitable for networks with high bandwidth requirements and high dynamic characteristics. Although the satellite network has a large communication coverage area, factors such as dynamic and time-varying topology, unstable links, unbalanced users of distribution and limited resources can easily cause serious network congestion and high transmission delay. The use of SDN to build a satellite network is conducive to solving the above-mentioned problems. This paper proposes a multi-path routing strategy based on SDN, which uses a combination of delay, bandwidth and node load to construct a link transmission cost calculation model, and adjusts the route for end-to-end transmission in time by real-time sensing of the network status and the load of the switching nodes in the network, thereby improving transmission efficiency. In particular, considering that the transmission delay of the satellite network is mainly determined by the propagation delay, this paper uses the Systems Tool Kit (STK) to establish the propagation delay model of the inter-satellite link to improve the accuracy of the transmission cost calculation. This paper compares the existing routing methods with the method in this paper on the Mininet simulation platform. The experimental results show that the method in this paper can effectively balance the bandwidth consumption of different links and improve the throughput of the network under the circumstance that the satellite network changes dynamically.

Content Distribution Based on Joint V2I and V2V Scheduling in mmWave Vehicular Networks

With the explosive growth of vehicle applications, vehicular networks based on millimeter wave (mmWave) bands have attracted interests from both academia and industry. mmWave communications are able to utilize the huge available bandwidth to provide multiple Gbps transmission rates among vehicles. In this paper, we address the content distribution scheduling problem in mmWave vehicular networks. It has been challenging for all vehicles in the same network to complete content downloading due to the limited communication resources of roadside units (RSUs) and the high mobility of vehicles. We propose a joint vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) scheduling scheme to minimize the total number of content distribution time slots from a global optimization perspective. In the V2I phase, the RSU serially transmits integrity content to vehicles, which are selected according to the vehicular network topology and transmission scheduling scheme. In the V2V phase, full-duplex communications and concurrent transmissions are exploited to achieve content sharing between vehicles and improve transmission efficiency. Performance evaluations demonstrate that our proposed scheme reduces the number of time slots and significantly improves system throughput when compared with other schemes, especially under large-size file transfers and a large number of vehicles.

Fault diagnosis of wet clutch control system of tractor hydrostatic power split continuously variable transmission

A hydrostatic power split continuously variable transmission (CVT) for a tractor often has multiple ranges to improve transmission efficiency. However, a failure of the wet-clutch control system will lead to interruption of tractor power and even endanger driving safety. To improve the reliability of CVT tractors, methods for diagnosing faults in the wet-clutch control system were studied. A test bench was built and the clutch engagement pressure was measured under different fault modes. For these time series data, statistics such as the mean, variance, kurtosis etc. were selected as features in the analysis. An improved Gaussian naive Bayes algorithm based on a time window as well as principal component analysis were used to classify the different fault modes of the clutch control system. Finally, the performance of the algorithm was analyzed. A test with multiple faults was run, as was a comparison with traditional algorithms. By optimizing the time window for data interception, the classification accuracy of the Gaussian naive Bayes algorithm for normal operation reached 97% and reached 100% for the fault modes. The average accuracy and recall rate of fault diagnosis were 98.2% and 89.4%, respectively, which are better than the results for a support vector machine, the k-nearest neighbors algorithm, or the decision tree algorithm. Importantly, the results show that the clutch pressure fluctuations during the shift by a tractor CVT can be used for the fault diagnosis of a clutch control system.

A Comparative Study of Birdcage RF Coil Configurations for Ultra-High Field Magnetic Resonance Imaging.

Improvements in transmission and reception sensitivities of radiofrequency (RF) coils used in ultra-high field (UHF) magnetic resonance imaging (MRI) are needed to reduce specific absorption rates (SAR) and RF power deposition, albeit without applying high-power RF. Here, we propose a method to simultaneously improve transmission efficiency and reception sensitivity of a band-pass birdcage RF coil (BP-BC RF coil) by combining a multi-channel wireless RF element (MCWE) with a high permittivity material (HPM) in a 7.0 T MRI. Electromagnetic field (EM-field) simulations, performed using two types of phantoms, viz., a cylindrical phantom filled with oil and a human head model, were used to compare the effects of MCWE and HPM on BP-BC RF coils. EM-fields were calculated using the finite difference time-domain (FDTD) method and analyzed using Matlab software. Next, to improve RF transmission efficiency, we compared two HPM structures, namely, a hollow cylinder shape HPM (hcHPM) and segmented cylinder shape HPM (scHPM). The scHPM and MCWE model comprised 16 elements (16-rad BP-BC RF coil) and this coil configuration demonstrated superior RF transmission efficiency and reception sensitivity along with an acceptable SAR. We expect wider clinical application of this combination in 7.0 T MRIs, which were recently approved by the United States Food and Drug Administration.

Broadband generation of abruptly autofocusing terahertz ring-Airy beams with all-silicon metasurface

Abruptly autofocusing terahertz (THz) ring-Airy beam has been generated by transmissive plasmonic metasurface at a single frequency in the earlier work. However, the transmission efficiency of it is low. Based on the waveguide effect, a design strategy for broadband generation of THz ring-Airy beams with transmissive all-silicon metasurface is proposed in this paper, which has an improved transmission efficiency and is more favorable in fabrication. Under the linearly polarized plane wave incidence, the amplitude and phase of the cross-polarized transmitted beam can be simultaneously modulated by controlling the rotation angles of the identical rectangular silicon pillars arranged on the silicon substrate. A polarization-independent antireflection square silicon pillar array is also proposed to be patterned at the other side of the substrate. The metasurface promises a working bandwidth from 2.12 to 2.72 THz with the overall transmission efficiency being over 51.18% (the highest transmission efficiency is up to 77.57% at 2.52 THz). The peak intensity positions of the generated beam during the propagation follow a parabolic trajectory. For the generated ring-Airy beam, the focal length is positively proportional to the frequency, while the abruptly autofocusing property and full width at half maximum (FWHM) of the focus are positively and negatively related with the frequency, respectively. This work can be expected to facilitate the applications of terahertz wave in biomedicine and manipulation of particles.

Vehicular Communication using Balanced Centralized and Decentralized Cluster Heads

A new approach to vehicular communication employing equal weights for distance and vehicular speed for centralized and decentralized communication is presented. The main objective of this work, which is to establish utilization expression and characteristics for an optimized balanced vehicular communication is achieved. The technique is based on analyzing effect of communication process (centralized, decentralized) on transmission efficiency and probability of failure. The analysis using utilization function, cluster head selection time, and end to end transmission time. The simulation and analysis concluded that the decentralization approach is more efficient compared to the centralized approach, so combination of both is proved to be effective. The work also uncovered the need for optimization of vehicular speed relative to transmission radius and use of zoning to effectively improve transmission efficiency. Mathematical models are presented that covers a critical relationship between probability of transmission failure, cluster head selection time and end to end delay. Also, an important mathematical expression that considers cluster head selection time and end to end delay and their effect on connection utilization is presented. The work proves that combined centralized and decentralized techniques using balanced weights approach is effective using dynamic weights selection algorithm that determines optimum weights for both used variables (distance, Vehicular speed).

Joint Doppler Shift and Channel Estimation for High-Speed Railway Wireless Communications in Tunnel Scenarios

In this work, we study the problem of Doppler shift and channel estimation for wireless communication systems on high-speed railways (HSRs). We focus on tunnel scenario, one of the classical scenarios of HSRs. We first build up the mathematical system model, design a joint Doppler shift and channel estimator, and compare its performance with the typical Moose algorithm. We show that our estimator outperforms the Moose algorithm in Doppler estimation. Besides, since wireless channels in tunnel scenarios often contain several or multiple taps, we suggest an adaptive frame structure to improve transmission efficiency. Simulations are then provided to corroborate our proposed studies.

Efficient n-M-PAWM hybrid modulation scheme for high data transmission in visible light communication system

Visible-Light Communications (VLC) is a new wireless communication technology, which has attracted particular attention as a promising solution for very high speed 5G, and 6G wireless networks in indoor environments. Intensity modulation (IM) is considered as the most appropriate modulation technique for VLC. This paper proposes to study a visible light communication (VLC) system with intensity modulation and direct detection (IM/DD). A channel modulation scheme is designed and encoded either in L-level pulse amplitude modulation (PAM), pulse position modulation (PPM), or pulse width modulation (PWM). In order to improve transmission efficiency, Hybrid Pulse Amplitude Position Modulation (PAPM) and Pulse Position Width Modulation (PPWM) are proposed in optical wireless communication (OWC), especially in VLC technologies. In this Paper, we propose a novel combination between PAM and PWM modulation schemes, called Pulse Amplitude Width Modulation (PAWM). The proposed modulation decreases the bit error ratio (BER) of VLC system, approximately 10−8 at Signal Noise Ratio (SNR) equal 12dB, and increases the system's transmission data rate to 210.8Mb/s at BER 10−7 for 2−4−PAWM. The normalized power and bandwidth requirements will be developed. The results show, from number M=32pulses per symbol, the transmission information rate ratio (IRR) is increased to3,75. Furthermore, a study of the Peak-to-Average Power Ratio (PAPR) for various hybrid modulations is conducted. Finally, the analytical expressions for power requirements and bandwidth, PAPR, and IRR expression of the proposed modulation scheme are investigated. The results show that the proposed hybrid modulation scheme could lower the BER and increase the data rate, and demonstrates the high potential implementation for VLC technology.

Joint Link Rate Selection and Adaptive Forward Error Correction for High-Rate Wireless Multicast

Multicast communication over wireless networks has many potential applications, such as real-time audiovisual content distribution or digital signage systems with multiple remote terminals. However, today’s common 802.11 networks cannot fully support such applications at the link layer due to the technical challenges in achieving both high transmission rate and high reliability for multicast data transfers. Those challenges primarily emerge from the inapplicability of immediate acknowledgment mechanisms of unicast transmissions to the multicast case and the need for finding a common transmission rate for all receivers with diverse channel conditions. The research literature in this domain mainly addresses the problem at the higher layers of the protocol stack. In this article, we present a novel approach that combines wireless link rate selection with an adaptive packet-level Forward Error Correction (FEC) mechanism in order to achieve high-rate and highly reliable multicast in 802.11 wireless networks. The integration of FEC into the 802.11 MAC layer allows direct interaction between the transmission rate and the coding scheme. As a result, potential packet losses caused by higher link rates can be compensated by the adjustable redundancy provided by FEC. In combination with an aggregated receiver feedback mechanism, this yields improved transmission efficiency and reliability for wireless multicast. We investigate this approach in a simulation environment under a realistic wireless channel model in various application scenarios with up to 50 receivers. The results represent significant performance improvements, in terms of throughput, channel utilization, and packet loss, over the state-of-the-art methods for reliable wireless multicast.

Optimal Hybrid Precoding Based QoE for Partially Structured Massive MIMO System

Precoding is a beamforming technique that supports multi-stream transmission in which the RF chain plays a significant role as a digital precoding at the receiver for wireless communication. The traditional precoding contains only digital signal processing and each antenna connects to each RF chain, which provides high transmission efficiency but high cost and hardware complexity. Hybrid precoding is one of the most popular massive multiple input multiple output (MIMO) techniques that can save costs and avoid using complex hardware. At present, network services are currently in focus with a wide range of traffic volumes. In terms of the Quality of Service (QoS), it is critical that service providers pay a lot of attention to this parameter and its relationship to Quality of Experience (QoE) which is the measurement of the overall level of user satisfaction. Therefore, this paper proposes hybrid precoding of a partially structured system to improve transmission efficiency and allocate resources to provide network services to users for increasing the user satisfaction under power constraints that optimize the quality of baseband precoding and radio frequency (RF) precoding by minimizing alternating algorithms. We focus on the web browsing, video, and Voice over IP (VOIP) services. Also, a Mean Opinion Score (MOS) is employed to measure the level of user satisfaction. The results show that the partially structured system provides a good user satisfaction with the network's services. The partially structured system provides high energy efficiency up to 85%. Considering web service, the partially structured system for 10 users provides MOS at 3.21 which is higher than 1.75 of fully structured system.

A model of service differentiation burst assembling and padding for improving transmission efficiency in OBS networks

Service differentiation is an indispensable requirement for transmission in optical burst switching (OBS) networks, which can be based on offset-time, burst-length, or both, offset-time and burst-length. The offset time based approach sets a large offset time for high priority bursts and a small offset time for low priority bursts. Whereas, with burst length based approach, high priority bursts are short in size and low priority bursts are long in length. A combination of these two approaches promises to provide flexible service differentiation. The paper proposes a model of service differentiation burst assembling and padding, in which the assembly time threshold is set to reduce the end-to-end delay, but does not effect the burst length prediction accuracy; the length of generated bursts are flexibly adjusted based on feedbacked void size; and the high-priority burst with short length is padded by the lower priority data. Simulation results and analysis show that the proposed model is more efficient than previous similar models in terms of bandwidth utilization, byte loss, throughput fairness and estimation error.

Improving LCC Series-Based Wireless Power Transfer System Output Power at High Temperature

Adding a core to a coupling coil can improve transmission efficiency. However, the added core causes the self-inductance of the coupling coil to increase at a high temperature due to the temperature-sensitive property of the core material’s permeability. The self-inductance increases, causing the resonance frequency to shift down, thereby decreasing the output power. The 3 dB bandwidth of the system can learn of the correspondence between the output power and the resonance frequency. In order to make sure that the output power does not excessively decrease at a high temperature, this study employs a simulation for the LCC-S-based wireless power transfer system. Adding a minor resistance to shift down the lower cutoff frequency ensures that the resonance frequency yielded by the temperature rise can be higher than the lower cutoff frequency, making the output power higher than half of the maximum. Then, an adjustment on the compensation capacitances on the resonant circuit elevates the output power more. The outcomes are consistent with the prediction. Adding the core to the coupling coil improves transmission efficiency; increasing the bandwidth of the system excessively decreases the output power decline at a high temperature for the temperature-sensitive core material permeability.

Improvement of transmission efficiency by using annular array metamaterial for magnetic coupling wireless power transmission system

Recently, the magnetic coupling wireless power transfer technology has been attracting a lot of attention and is expected to have a wide range of applications in the electrical equipment around us. On the other hand, there have been reports on the application of metamaterials for the purpose of improving antenna gain and suppressing mutual coupling between antennas, and this study aim applying this technique to the magnetic coupling wireless power transfer system. In this paper, a magnetic wall by meta material suitable for a magnetic coupling wireless transfer system is proposed and its effect is demonstrated experimentally.

Research on the torsional vibration performance of a CVT powertrain with a dual-mass flywheel damper system

Continuously variable transmissions (CVTs) can achieve continuous changes in speed ratio and can better improve the ride comfort of the car. However, the torque fluctuation of the engine will reduce its transmission efficiency, and the torsional damper is usually matched to improve transmission efficiency and reduce vibration noise. In this paper, the model of a complete vehicle power transmission system was established by using the bond graph method. The relationships between each state variable were obtained according to the system causality and the direction of the power flow, based on which the dynamic model of the entire vehicle power transmission system was derived. A simulation of the powertrain with dual-mass flywheel-continuously variable transmission (DMF-CVT) was carried out, and the torsional stiffness of the dual-mass flywheel (DMF) was optimized. Taking a certain sport-utility vehicle (SUV) as the test bench, the vehicle road testing of the DMF before and after improvement was carried out, and the test results before and after the improvement were compared to verify the correctness of the optimization direction, which provided a reference for the matching and optimization design of the DMF-CVT power transmission system.

A new near-lossless image information hiding algorithm with controlled hiding capacity

Image information hiding technology can embed more data without increasing the amount of transmitted data. But in most cases, the information embedding rate is different for different carrier images. To increase the embedding rate, the data will be damaged. In order to improve this problem, a new near-lossless image information hiding algorithm with controlled hiding capacity is proposed, which is referred to as NLH. This method makes the pre-processed data in a specific range to facilitate information hiding by interval transformation and data mapping. According to analysis and calculation, the lossless performance of the proposed algorithm in this paper is better than the LSB algorithm. And the result of simulation shows that this method has a fixed information embedding rate (18.75%/1.5bpp) without more transmitted data, and the original image is restored losslessly or nearly losslessly with the improved transmission efficiency.

A novel Fabry–Pérot (FP) antenna with high gain, low radar-cross-section (RCS), and wideband circular polarization

AbstractWe propose a novel Fabry–Pérot (FP) antenna consisting of a checkered polarization-conversion metasurface (PCM), corner-cut square patch antennas, and sandwiched compounds. The proposed antenna achieves low radar-cross-section (RCS), high gain, and wideband circular polarization (CP). The corner-cut square patch antennas facilitate high reflectivity, satisfactory transmission magnitude, and the desired phase difference. An embedded metal between two rings of substrate contributes to reducing cross-polarization, improving transmission efficiency, enhancing bandwidth, and reducing RCS. Following simulations, we fabricated a prototype of the proposed antenna and tested its performance. Measurements from the simulation and prototype tests were similar within a reasonable margin of error. Compared with alternative antennas, our proposed FP antenna offers high gain, wideband CP, low cost, a low RCS, and a lower profile.

Device-to-device (D2D) reliable transmission in the internet of things

D2D stands for device-to-device communication, which is likely to perform a major impact in future mobile communications because it offers ultra-low latency for end user’s direct conversation. Throughout minimizing latency, increasing strength and improved transmission efficiency, and expanding telecommunication services, D2D services are seen as a successful innovation for emerging mobile communications. The D2D networking makes a unique contribution to the wireless world by simplifying data transfer among devices connected. D2D networking makes use of adjacent two nodes to maximize the use of existing infrastructure, low latency, boost throughput and expand service functionality. Within wireless networks, D2D communication is described as immediate interaction among two mobile devices without passing through the access point or network infrastructure. The fully integrated wireless communication would be built by integrating D2D and the Internet of Things. D2D enables the larger number of devices to be paired at a higher bandwidth frequency and with minimum latency. Building a new reliable framework for D2D communication of smart devices can be an important framework for improving the reliability of communication. Internet of Things is the process of communicating and sharing information between nearby devices. But there are many challenges to secure and reliable communication. Amongst the major concerns for wireless transmission has been identified as communication trust, and overcoming this issue could lead to sustained expansion in the usage and popularity of the Internet of Things. The proposed study develops a system for providing internet access to a network of smart devices connected to the internet of things. The significant contributions link the latest findings that incorporate the interaction framework's stability and provides secure internet networking for connected devices.

Design and Control Method of Power-Cycling Variable Transmission System

A design theory of a power-cycling variable transmission (PCVT) system with improved transmission efficiency and continuously variable transmission characteristics was proposed for preserving the characteristics of transmission types such as the friction, hydrodynamic, and hydraulic drives. This study expounds on the structure and working principle of PCVT, analyzes its main characteristics, and describes its unique performance through a series of design examples.

Gradient-Free Scheduling of Fog Computation for Marine Data Feedback

With the development of the marine Internet of Things (IoT), more sensors are deployed for different marine applications. Abundant data are generated that are required by terrestrial users. However, nowadays, the marine Internet cannot provide enough communication resources and high service quality for the feedback of those data. Thereby, fog computation is a potential method to solve this problem via data compression before transmission. To improve transmission efficiency while guaranteeing Quality of Service (QoS) of applications, how to efficiently schedule limited computation resources at fog nodes, such as buoys for different applications should be addressed. This article proposes an online computation scheduling algorithm to improve the communication resource efficiency with guaranteed QoS via appropriate compression. This scheme needs neither the cost function nor the constraint function at the scheduling node. What is more, the gradient information, which is usually needed in learning strategies, is not required, which is the estimation based on first-order and second-order schemes, respectively. Results show that the proposed scheme achieves the goal of improving communication efficiency while guaranteeing the data quality constraint of different applications.

High-efficiency and compact WPT receiving antenna design using simulation optimization method

In this paper, a high-efficiency and compact wireless power transfer (WPT) receiving antenna using an flexible printed circuits board (FPCB) with high-Q factor is proposed. The proposed high-efficiency and compact WPT receiving antenna consists of a spiral structure, a lumped element and via through the ground structure. In this paper, in order to design a miniaturized high-efficiency WPT receiving antenna, machine learning technology was used to optimally design the antenna pattern that affects the Q factor. The designed receiving antenna has improved wireless power transmission efficiency with high Q characteristics. The power transfer efficiency is above 88% from distance 10 mm and the resonant frequency is 110 MHz. The sizes of the receiving antenna and the NFC antenna are 30 × 40 mm and 20 × 30 mm, respectively. Machine learning was used to design and fabricate the composite module of a WPT receiving antenna and NFC antenna. Comparison of the experimental results of the proposed receiving antenna with a general receiving antenna confirms the improvement in transmission efficiency.