Transmission Rate Performance Research Articles

Hermetic, Hybrid Multilayer, Sub‐5µm‐Thick Encapsulations Prepared with Vapor‐Phase Infiltration of Metal Oxides in Conformal Polymers for Flexible Bioelectronics

AbstractReliable long‐term function is crucial for flexible and soft bioelectronics. Mechanical defects and permeation of water molecules across the various device layers are the prime drivers of failure, and particularly in applications requiring continuous contact with biofluids (i.e. for implantable applications). To address demanding needs of miniaturization, mechanical compliance and water impermeability, ultra‐thin high‐barrier encapsulations are a promising way to improve device reliability. In this work, the encapsulation properties of vapour phase infiltration (VPI) of inorganic Al2O3 layers deposited by atomic layer deposition (ALD), as bilayers with TiO2, onto polyimide and parylene C organic substrates are investigated. The layers are grown in a single reactor and the infiltration is performed in a single process, with a resulting nanometric infiltration depth. Mechanical integrity and hermeticity are characterized through tensile fragmentation tests and accelerated aging tests. Flexible Magnesium sensors monitor water vapor permeability in situ. A remarkable improvement in the crack onset strain (∽2.56 times), interfacial shear strength (∽2.1 times), water vapour transmission rate (∽5.2 times) and lifetime performance (∽7.1 times) is achieved, compared to the non‐infiltrated ALD coatings. Pluri‐infiltrated multilayers are proposed as alternatives to conventional coatings. This work is envisioned to accelerate research progress on hermetic packaging of flexible bioelectronics.

Device-compatible ultra-high-order quantum noise stream cipher based on delta-sigma modulator and optical chaos

Data security is a key feature of future communications networks. Physical layer introduces rich physical mechanisms to increase the complexity of deciphering and provides extensive protection, but faces challenges in compatibility with commercial systems. Quantum noise stream cipher (QNSC) has been proposed as a promising solution to overcome this problem by fusing the stream cryptography regime with the quantum noise masking physical mechanism. However, it has limitations in terms of digital to analog conversion and clock data synchronization of ultra-high-order ciphertext as well as flexible control of masking noise. Here we report a 147.9-Gbps device-compatible quadrature amplitude modulation (QAM) QNSC secure scheme over 75-km fiber. Thanks to delta-sigma modulator, the transmission of 220 × 220-order QAM-QNSC signal are established through the low-order digital signal. We develop a theoretical model for flexibly regulating the transmission rate and security performance. Broadband optical chaos introduces true randomness and acts on the masking noise.

A Multiagent Meta-Based Task Offloading Strategy for Mobile-Edge Computing

Task offloading in mobile edge computing (MEC) improves the efficacy of mobile devices in terms of computing performance, data storage, and energy consumption by offloading computational tasks to edge servers. Efficient task offloading can leverage MEC technology to reduce task processing latency and energy consumption. By integrating the reasoning ability and machine intelligence of the cognitive computing architecture, such as SOAR and ACT-R, reinforcement learning (RL) algorithms have been applied to resolve the task offloading in MEC. To solve the problem that conventional Deep RL (DRL) algorithms cannot adapt to dynamic environments, this paper proposed a task offloading scheduling strategy which combined multi-agent reinforcement learning and meta-learning. In order to make the two actions of charging time and offloading strategy fully considered at the same time, we implemented a learning network of two agent on a mobile device. To efficiently train the policy network, we proposed a first order approximation method based on clipped surrogate objective. Finally, the experiments are designed with variety of the number of subtasks, transmission rate, and edge server performance, and the results show that the MRL-based strategy has the overwhelming overall performance and can be quickly applied in various environments with good stability and generalization.

Development and Characterization of Soy Protein Isolate/Xylose Film

This paper used different concentrations of xylose as a cross‐linker to initiate the Maillard reaction with the soy protein isolate matrix. The mechanical performance and moisture resistance of the soy protein isolate film were enhanced. Measuring the specific wavelength absorbance, free amino group concentration, and fluorescence spectrum of the cross‐linked result revealed the alteration of the soy protein isolate. Simultaneously, composite films made by crosslinking soy protein isolate with xylose were thoroughly investigated. Mechanical properties, contact angle measurement, water vapour transmission rate, optical properties, and thermal performance were used to determine the film’s fundamental properties, and the interaction relationship between soy protein isolate, xylose, and glycerol was studied using infrared spectroscopy. The study found that the modified SPI film outperformed the unmodified film, particularly when the xylose content was 20%. The tensile strength reached 6.26 MPa, and the water vapour permeability was reduced to 5.45 × 10−8 g·mm/m2·s·Pa. It also exhibited excellent UV resistance and good thermal stability.

Design analysis and optimization of chaotic systems for duration and carrier parallel index modulation

With the rapid advancement in communication technology, the demand for high speed and efficient transmission has increased significantly. Traditional communication systems are unable to meet these demands, and thus, this paper proposes a new correlated delay shift keying system for duration and carrier parallel index modulation (DCIM-CDSK) that employs duration and carrier parallel index modulation. The DCIM-CDSK system utilizes index mapping to transmit extra bits, while group mapping the timeslots on the carrier. By using spare timeslots in each group to transmit modulated information bits, the system achieves high-speed transmission with high efficiency. Additionally, the system introduces a noise reduction method to optimize the information-carrying signal to improve its noise immunity. The theoretical bit error rate (BER) equations is derived in the paper for the DCIM-CDSK system under Gaussian and Rayleigh fading channels, and compared them with practical simulations to validate the theoretical derivation. The paper also analyzes the BER of the system for a single longest timeslot length and mixed longest timeslot length, respectively. The simulation results show that the proposed DCIM-CDSK system has better noise immunity and higher transmission rates than other similar systems. In today's increasingly stringent requirements for communication systems, the DCIM-CDSK system, with its high spectral and energy efficiency, provides a feasible solution for the current communication system industry to realize large user group services and high bandwidth utilization efficiency. At the same time, because of the flexibility of the system between the transmission rate and BER performance, the communication system can get a better trade-off and balance between the two contradictions of effectiveness and reliability.

Distributed Joint Channel Assignment and Power Control for Sum Rate Maximization of D2D-Enabled Massive MIMO System

Device-to-device (D2D) communications underlaid massive multiple-input multiple-output (MIMO) systems have been recognized as a promising candidate technology to achieve the challenging fifth-generation (5G) network requirements. This integration enhances network throughput, improves spectral efficiency, and offloads the traffic load of base stations. However, the co/cross-tier interferences between cellular and D2D communications caused by resource sharing is a significant challenge, especially when dense D2D users exist in an underlay mode. In this paper, we jointly optimize the channel assignment and power allocation to maximize the sum data rate while maintaining the interference constraints of cellular links. Due to the lack of network-wide information in large scale networks, resource management and interference coordination is hard to be implemented in a centralized way. Therefore, we propose a three-stage stable and distributed resource allocation and interference management scheme based on local information and requires little coordination and communication between devices. We model the channel allocation optimization problem in the first stage as a many-to-one matching game. In the second stage, the algorithm adopts a cost charging policy to solve each user’s power control problem as a non-cooperative game. In the third stage, the algorithm search for swap blocking pairs until stable matching exist. It is shown in this paper that the proposed algorithm converges to a stable matching and terminates after finite iterations. Simulation results show that the proposed algorithm can achieve more than 86% of the average transmission rate performance of the optimal matching with lower complexity.

Research progress on chemical looping reforming of macromolecular components of volatiles from biomass pyrolysis based on decoupling strategy

This paper focuses on the development of chemical-looping reforming of macromolecular organic compounds from biomass pyrolysis based on decoupling strategy, including glycerol, benzene, and toluene. Firstly, the influence characteristics of pyrolysis conditions on the distribution of volatile are analyzed. Pyrolysis temperature and heating rate are the two most important factors. Three technical routes to prepare hydrogen-rich syngas by chemical-looping reforming of typical macromolecular components in the volatile components of biomass pyrolysis were emphatically discussed, which include auto-thermal chemical-looping reforming (CLRa), chemical-looping steam reforming (CLSR), and chemical-looping dry reforming (CLDR). The types of oxygen carriers, reforming characteristics, and reaction mechanisms related to the above three routes were compared. In the future, chemical-looping reforming based on the decoupling strategy focuses on developing oxygen carriers with high lattice oxygen reserves, fast transmission rate and good anti-coke formation performance, and more efficient fluidized bed reactors. At the same time, density functional theory calculations and reaction experiments combined to reveal the reaction mechanism, integrate and optimize the system's energy flow and material flow.

Optimization of precoders and rate allocation for Rate Splitting Multiple access over power line communication channel

We consider a transmission scheme of Rate Splitting Multiple access systems over a power line communication channel in this paper. The System model consists of a transmitter and K users, and superimposing signals for K users at the transmitter. Our aim is to maximize the worst transmission rate between users in the system by jointly optimizing the precoder vector and rate allocation with the method of successive convex approximation(SCA). The simulation results manifest that compared with PLC-NOMA, PLC-RSMA adapts to various channel directions (regardless of whether the channel directions are aligned or orthogonal) and network load (underload or overload), PLC-RSMA can reach better transmission rate performance, and as the SNR augment, the rate performance gain of PLC-RSMA becomes more and more obvious. Under the set parameters, when the SNR is 30 dB, the relative rate performance of PLC-RSMA is improved by at least 27% compared to PLC-NOMA.

Transparent and high barrier plasma functionalized acrylic coated cellulose triacetate films

Transparent and high moisture barrier acrylic coatings were obtained by deposition of acrylic resin containing crosslinking agents onto cellulose ester films, followed by exposure to atmospheric plasma. The effects of monomers, crosslinking agents, and polymerization methods were studied. The surface chemical composition, morphology, water vapor transmission rate (WVTR), light transmittance, and adhesion performance of the coated cellulose triacetate (CTA) films were characterized for the acrylic coated films and for different plasma treatments. Coated films showed a significant reduction in water vapor permeability while maintaining excellent transparency when compared with uncoated films. Furthermore, adhesion of the coating to the CTA film was also improved due to plasma treatment. It was also found that plasma curing on the coated oligomers can induce morphological changes and significantly increase surface roughness and hydrophilicity. The roughness texture observed via SEM analysis indicated that the types of plasma polymerization and the amount of crosslinking agents control the texture types for acrylic coating. Plasma-assisted acrylic coated CTA films can be used in electronic displays, medical, and packaging applications.

Dynamic Virtual Resource Allocation for 5G and Beyond Network Slicing

The fifth generation and beyond wireless communication will support vastly heterogeneous services and user demands such as massive connection, low latency and high transmission rate. Network slicing has been envisaged as an efficient technology to meet these diverse demands. In this paper, we propose a dynamic virtual resources allocation scheme based on the radio access network (RAN) slicing for uplink communications to ensure the quality-of-service (QoS). To maximum the weighted-sum transmission rate performance under delay constraint, formulate a joint optimization problem of subchannel allocation and power control as an infinite-horizon average-reward constrained Markov decision process (CMDP) problem. Based on the equivalent Bellman equation, the optimal control policy is first derived by the value iteration algorithm. However, the optimal policy suffers from the widely known curse-of-dimensionality problem. To address this problem, the linear value function approximation (approximate dynamic programming) is adopted. Then, the subchannel allocation Q-factor is decomposed into the per-slice Q-factor. Furthermore, the Q-factor and Lagrangian multipliers are updated by the use of an online stochastic learning algorithm. Finally, simulation results reveal that the proposed algorithm can meet the delay requirements and improve the user transmission rate compared with baseline schemes.

A FPGA implementation of GMM MUD algorithm for space formation aircraft communication system

Space formation aircraft communication system needs to meet strong anti-interference ability, low power consumption and high transmission rate performance. Ultra-wideband (UWB) has high data transfer rate, low device complexity, high interference resistance and confidentiality. Therefore, UWB technology is used in space formation aircraft communication system, which is direct sequence ultra-wideband (DS-UWB) space formation aircraft communication system. This paper, we put forward a multi-user detection (MUD) algorithm based on Gaussian Mixture Model (GMM) in DS-UWB communication system and its field-programmable gate array (FPGA) implementation. We adopt a way which based on MATLAB and FPGA platform, and results show that MUD algorithm based on GMM has better bit error rate (BER) performance compared to classical multi-user detection algorithm.

A low‐profile circularly polarized transmitarray antenna using rotated cross dipole elements

A low profile circularly polarized (CP) transmitrarray using double-layer cross dipole elements is presented in this letter. The proposed element exhibits an overall thickness of only 0.22λ0, which offers the advantages of light weight, easy fabrication, and low cost compared to conventional transmitarray elements. The transmission coefficient of the element is analyzed by Ansys HFSS, and the results show that the element manifests a high transmission rate and good CP performance. Then, by using angular rotation technique, transmitarray with this type of element is designed, fabricated, and tested. The size of the transmitarray is 6.6 × 6.6λ0 at the center frequency of 10 GHz. The measured peak gain is 22.5 dB at 9.5 GHz, resulting in an aperture efficiency of 36%. The measured 1-dB gain and 3-dB axial ratio bandwidths are 10.2% and 12%, respectively.

Performance Analysis for MIMO SWIPT Systems with Space-Time Coding

Energy supply is a key factor affecting the normal operation of energy-constrained networks. Simultaneous wireless information and power transfer (SWIPT) technology can be used to obtain a stable and continuous energy source. But SWIPT need to take into account data transmission rate and energy harvesting performance, it is necessary to design a complex physical layer method to improve the energy efficiency of SWIPT system. The paper studies a multiple input multiple output (MIMO) SWIPT system based on space-time coding, the transmitter sends the information using the space-time encoder through multi-antenna transmission, the receiver uses the space-time decoder to decode the information and collect the energy. The expressions of channel capacity and energy harvesting under MIMO are given respectively. The energy harvesting optimization target equation under coding conditions is established. The simulation results show that the using of space-time coding can reduce the data transmission error rate of MIMO SWIPT system and improve the energy harvesting performance of the user terminals.

OCC-Selection-Based High-Efficient UWB Spatial Modulation System Over a Multipath Fading Channel

In this paper, an orthogonal complementary code (OCC)-selection-based high-efficient ultrawideband (UWB) spatial modulation (SM) system has been proposed to achieve higher transmission rate and better system performance. The OCC is employed to spread the spectrum, carry extra information bits, and alleviate the multipath interference simultaneously. Meanwhile, the SM technique is adopted to further increase the system bit rate and overcome the synchronization and interference issues of a multiantenna system. In the proposed UWB SM system, the information bits are conveyed through three ways: direct bipolar pulse amplitude modulation, indirect spread spectrum code selection, and transmit antenna selection. To further enhance the system performance over a multipath fading channel, the selective Rake receiver and maximum ratio combining detection are utilized. A closed-form expression of the system bit error rate is derived through the moment-generating function. Numerical results are provided to verify the theoretical analysis and show the efficiency and performance improvement of the proposed OCC-selection-based UWB SM system.

Effects of nanosilica and titanium oxide on the performance of epoxy–amine nanocoatings

ABSTRACTDifferent types of composite coatings were prepared by the blending of colloidal nanosilica (SiO2) and titanium dioxide (TiO2) in epoxy resin to investigate their coating performances. A fixed amount of silica nanoparticles (20 wt %) and different amounts (5, 10, and 15 wt %) of microsized TiO2 particles were used in the coatings. The functional groups of the formulated coatings were confirmed by Fourier transform infrared spectroscopy. These results indicate that the SiO2–TiO2 particles interacted well with epoxy. Scanning electron microscopy images of the composite coatings revealed a good dispersion of TiO2 particles at a lower amount of loading; this improved the adhesiveness, glass‐transition temperature, thermal stability, and chemical resistance properties. At higher loadings, the performances decreased. The composite coatings were also characterized by their UV radiation‐absorption properties with an ultraviolet–visible spectrophotometer. Interestingly, this property was found to be enhanced at higher loadings. An impressive result was noticed in the nanocomposites in terms of oxygen transmission rate performance compared to that of the neat epoxy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47901.

Optimum SWIPT relaying in bidirectional non‐regenerative relay networks

The authors study the optimal design of simultaneous wireless information and power transfer relaying in bidirectional non-regenerative relay networks. They consider both power splitting relaying and time switching relaying. Since there are two opposite traffic flows between two sources, they characterise the transmission rate performance by the minimum rate of two opposite traffic flows. Specifically, they first obtain closed-form expressions for the optimum power splitting and time switching coefficients to maximise the minimum transmission rate of bidirectional non-regenerative relaying. They also derive the resulting maximum transmission rate expressions. Furthermore, they consider a minimum input radio frequency (RF) power level to turn on diodes, and derive the turn-on probability of the RF energy harvesting circuit when two channels experience independent Rayleigh fading. Numerical results confirm that the authors' analyses exactly match with simulation results and that the two relaying strategies with optimum coefficients give almost the same transmission rate performance.

Effective Resource Utilization Schemes for Decode-and-Forward Relay Networks With NOMA

This paper investigates an effective resource utilization scheme for the decode-and-forward (DF) cooperative relaying networks (CRNs) with non-orthogonal multiple access (NOMA). Considering a T time slots transmission, the proposed effective resource utilization scheme adopts max-min relay selections to satisfy the quality-of-service (QoS) and provide a higher priority. Unlike the conventional CRNs, to improve the system performance and resource utilization, the unselected relays will continue receiving the signals transmitted by the base station (BS), as well as the selected relays forward the decoded signals to the user equipment (UE). Moreover, the maximum ratio combining (MRC) is utilized at the UE to jointly detect the receptions for each time slot. The achievable average sum-rate (SR) of the proposed system is analyzed for independent Rayleigh fading channels, and the asymptotic expressions are also provided. The qualitative numerical results corroborating our theoretical analysis show that the proposed effective resource utilization scheme significantly improves the transmission rate and SR performance in comparison to the conventional CRN-NOMA schemes.

Collaborative Energy and Information Transfer in Green Wireless Sensor Networks for Smart Cities

Smart city is able to make the city source and infrastructure more efficiently utilized, which improves the quality of life for citizens. In this framework, wireless sensor networks (WSNs) play an important role to collect, process, and analyze the corresponding information. However, the massive deployment of WSNs consumes a significant energy consumption, which has raised the growing demand for green WSNs for smart cities. Exploiting the recent advance in collaborative energy and information transfer to power the WSNs and transmit the data has been considered a promising approach to realize the green WSNs for smart cities. We propose an architecture design of the green WSNs for smart cities, by exploiting the collaborative energy and information transfer protocol, and illustrate the challenging issues in this design. To achieve a green system design, the sensor nodes in WSNs harvest the energy simultaneously with the information decoding (ID) from the received radio frequency signals. Specifically, the energy-constrained sensor nodes partition the received signals into two independent groups to perform energy harvesting (EH) and ID. The sensor nodes then use the harvested energy to amplify and forward the information signals. We study the joint optimization of subcarrier grouping, subcarrier pairing, and power allocation such that the transmission rate performance is maximized with the EH constraint. The joint optimization problem is solved via dual decomposition after transforming it into an equivalent convex optimization problem. Simulation results tested with the real WSNs system data indicate that the performance of our proposed protocol can be significantly improved.

Modulation in the Air: Backscatter Communication Over Ambient OFDM Carrier

Ambient backscatter communication (AmBC) enables radio-frequency (RF) powered backscatter devices (BDs) (e.g., sensors and tags) to modulate their information bits over ambient RF carriers in an over-the-air manner. This technology, also called “modulation in the air,” has emerged as a promising solution to achieve green communication for future Internet of Things. This paper studies an AmBC system by leveraging the ambient orthogonal frequency division multiplexing (OFDM) modulated signals in the air. We first model such AmBC system from a spread-spectrum communication perspective, upon which a novel joint design for BD waveform and receiver detector is proposed. The BD symbol period is designed as an integer multiplication of the OFDM symbol period, and the waveform for BD bit “0” maintains the same state within the BD symbol period, while the waveform for BD bit “1” has a state transition in the middle of each OFDM symbol period within the BD symbol period. In the receiver detector design, we construct the test statistic that cancels out the direct-link interference by exploiting the repeating structure of the ambient OFDM signals due to the use of cyclic prefix. For the system with a single-antenna receiver, the maximum-likelihood detector is proposed to recover the BD bits, for which the optimal threshold is obtained in closed-form expression. For the system with a multi-antenna receiver, we propose a new test statistic which is a linear combination of the per-antenna test statistics and derive the corresponding optimal detector. The proposed optimal detectors require only knowing the strength of the backscatter channel, thus simplifying their implementation. Moreover, practical timing synchronization algorithms are proposed for the designed AmBC system, and we also analyze the effect of various system parameters on the transmission rate and detection performance. Finally, extensive numerical results are provided to verify that the proposed transceiver design can improve the system bit-error-rate performance and the operating range significantly and achieve much higher data rate, as compared with the conventional design.

Game‐Theoretic Social‐Aware Resource Allocation for Device‐to‐Device Communications Underlaying Cellular Network

Device‐to‐Device communication underlaying cellular network can increase the spectrum efficiency due to direct proximity communication and frequency reuse. However, such performance improvement is influenced by the power interference caused by spectrum sharing and social characteristics in each social community jointly. In this investigation, we present a dynamic game theory with complete information based D2D resource allocation scheme for D2D communication underlaying cellular network. In this resource allocation method, we quantify both the rate influence from the power interference caused by the D2D transmitter to cellular users and rate enhancement brought by the social relationships between mobile users. Then, the utility function maximization game is formulated to optimize the overall transmission rate performance of the network, which synthetically measures the final influence from both power interference and sociality enhancement. Simultaneously, we discuss the Nash Equilibrium of the proposed utility function maximization game from a theoretical point of view and further put forward a utility priority searching algorithm based resource allocation scheme. Simulation results show that our proposed scheme attains better performance compared with the other two advanced proposals.