Layer Transmission Research Articles

Enhancing covert communication in NOMA systems with joint security and covert design.

The explosion of Internet-of-Thing enables several interconnected devices but also gives rise chance for unauthorized parties to compromise sensitive information through wireless communication systems. Covert communication therefore has emerged as a potential candidate for ensuring data privacy in conjunction with physical layer transmission to render two lines of defense. In this paper, we aim to enhance the individual transmission of nearby users in non-orthogonal multiple access (NOMA) systems under scenarios of an eavesdropper who monitors covert transmission before decoding covert information. For this problem, we first provide a comprehensive analysis of the NOMA system in terms of outage probability (OP), secrecy outage probability (SOP), and detection error probability (DEP), where all of them are quantified in exact and asymptotic closed-form expressions. Besides, we have also derived closed-form formulas for users' covert and public rates. Under the system requirements of the maximal OP and SOP and the minimal DEP, we formulate the optimization of resource power allocation to: 1) minimize the OP of covert communication and 2) maximize the covert rate. Thanks to the developed analytical expressions, we obtain closed-form expressions for the sub-optimal power allocation coefficient for each problem. Simulation results validate the efficacy of the analytical mathematical frameworks and reveal that the proposed approaches of power allocation can provide attractive performance improvement compared to fixed power allocations only.

MUL-VR: Multi-UAV Collaborative Layered Visual Perception and Transmission for Virtual Reality

MUL-VR: Multi-UAV Collaborative Layered Visual Perception and Transmission for Virtual Reality

Open‐set recognition of specific emitter based on complex‐valued convolutional neural network

AbstractSpecific emitter identification (SEI) plays an important role in enhancing physical layer transmission security. However, with the promotion of wireless technology, the environment is filled with a large number of unknown wireless signals. SEI will face a more challenging scenario referred to as “open set.” To cope with the above difficulties, an open‐set recognition (OSR) model based on complex‐valued convolutional neural network (CVCNN) is proposed. The CVCNN can adapt to IQ signal input and extract complex domain features. Furthermore, a novel inter‐class loss is proposed to effectively improve the classification performance. Finally, the classifier is designed based on the incremental approach. It can continuously learn new classes to achieve the recognition of multiple unknown emitters. The experiments show that compared with the real‐valued convolutional neural network and the single loss function, the accuracy is improved by 3.8% and 10%, respectively.

UV‐Induced Degradation of Industrial PERC, TOPCon, and HJT Solar Cells: The Next Big Reliability Challenge?

With the surge of UV‐transparent module encapsulants in the photovoltaic industry aiming to boost quantum efficiency, modern silicon solar cells must now inherently withstand UV exposure. UV‐induced degradation (UVID) of nonencapsulated laboratory and industrial solar cells from several manufacturers is investigated. Passivated emitter rear contact (PERC), tunnel oxide passivating contact (TOPCon), and silicon heterojunction (HJT) cells can suffer from severe implied voltage degradation (>20 mV) after UV exposure relating to 3.8 years of module installation in the Negev desert. Front UV‐exposure causes more performance loss than an equal rear dose. This is connected to a higher UV transmission of the cell layers outside the bulk, indicating the photons need to reach the silicon surface to induce damage. Current–voltage measurements of the TOPCon groups most sensitive to UV degradation show more than 7%rel efficiency loss with the Voc as the main contributor. For two TOPCon groups, dark storage for 14 days after UV exposure causes an additional voltage drop on a similar scale as the UV damage itself, impeding straightforward reliability testing. UVID appears to be a complex process general to all dominant cell architectures with the potential to diminish efforts in efficiency optimization within only a few years of field employment.

The elevated open platform stress suppresses excitatory synaptic transmission in the layer V anterior cingulate cortex

There are various forms of stress including; physical, psychological and social stress. Exposure to physical stress can lead to physical sensations (e.g. hyperalgesia) and negative emotions including anxiety and depression in animals and humans. Recently, our studies in mice have shown that acute physical stress induced by the elevated open platform (EOP) can provoke long-lasting mechanical hypersensitivity. This effect appears to be related to activity in the anterior cingulate cortex (ACC) at the synaptic level. Indeed, EOP exposure induces synaptic plasticity in layer II/III pyramidal neurons from the ACC. However, it is still unclear whether or not EOP exposure alters intrinsic properties and synaptic transmission in layer V pyramidal neurons. This is essential because these neurons are known to be a primary output to subcortical structures which may ultimately impact the behavioral stress response.Here, we studied both intrinsic properties and excitatory/inhibitory synaptic transmission by using whole-cell patch-clamp method in brain slice preparations. The EOP exposure did not change intrinsic properties including resting membrane potentials and action potentials. In contrast, EOP exposure suppressed the frequency of miniature and spontaneous excitatory synaptic transmission with an alteration of kinetics of AMPA/GluK receptors. EOP exposure also reduced evoked synaptic transmission induced by electrical stimulation. Furthermore, we investigated projection-selective responses of the mediodorsal thalamus to the layer V ACC neurons. EOP exposure produced short-term depression in excitatory synaptic transmission on thalamo-ACC projections. These results suggest that the EOP stress provokes abnormal excitatory synaptic transmission in layer V pyramidal neurons of the ACC.

Analysis of solar absorption, degradation mechanism and thermal stability in air environments for SS/TiB2/Al2O3 spectrally selective absorber coating

The quest for high solar-thermal conversion efficiency and thermal stability is a significant challenge in the development of high-efficiency spectrally selectivity absorber coatings. A key aspect of this challenge is the creation of air-stabilized coatings, particularly crucial for scenarios involving unexpected vacuum loss or applications of concentrating solar power systems in air environments. In our study, TiB2 films own excellent spectral selectivity and thermal stability at air environment. In pursuit of revealing the absorption mechanism of the coating, the optical constants, absoption and transmission of the single TiB2 layer were measured. The result of analysis display that the TiB2 layer contribute the bulk of the sunlight absorption. Reflectance spectra of the SS/TiB2/Al2O3 coating was succeeding simulated by CODE software with the optical constant to fit the experimental spectra, which confirms the results obtained by spectroscopic ellipsometry. The solar-thermal conversion efficiency of the as-deposited coating could reach 88.9 % of 100 suns at 500 °C. After annealing at 300–500 °C, the absorbance and emittance of the coating change slightly. But after annealing at 600 °C, the changing surface morphology, increasing surface roughness, and oxidation reaction of TiB2 resulted in a decrease in the optical performance of the coating.

A physical layer security enhancement scheme for CO-OFDM systems based on 3D Brownian motion and TZBN Joint Scramble

In this paper, we propose a scheme for enhancing the physical layer security and transmission performance of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. The scheme for OFDM data first after 3-dimensional (3D) Brownian motion rotational permutation, and then according to the time zone and band number (TZBN) scrambling to achieve the effect of further data perturbation, which through the SHA-256 algorithm and 6-dimensional (6D) hyperchaotic processing to obtain the chaotic keys to enhance the security. After simulation experiment of 16QAM CO-OFDM security system transmitting over 80 km standard single-mode fiber (SSMF) at the symbol rate of 30 Gbaud, it is shown that the encryption scheme can guarantee that the authorized user receives valid data and the eavesdropper obtains the information with the BER of about 0.5. The key space of the scheme is about 2.88×10194, which can effectively resist attacks such as violent attacks and chosen plaintext attacks. And the peak-to-average power ratio (PAPR) can be reduced by about 1.09 dB while the encryption process.

Withdrawal from chronic alcohol impairs the serotonin-mediated modulation of GABAergic transmission in the infralimbic cortex in male rats

The infralimbic cortex (IL) is part of the medial prefrontal cortex (mPFC), exerting top-down control over structures that are critically involved in the development of alcohol use disorder (AUD). Activity of the IL is tightly controlled by γ-aminobutyric acid (GABA) transmission, which is susceptible to chronic alcohol exposure and withdrawal. This inhibitory control is regulated by various neuromodulators, including 5-hydroxytryptamine (5-HT; serotonin). We used chronic intermittent ethanol vapor inhalation exposure, a model of AUD, in male Sprague-Dawley rats to induce alcohol dependence (Dep) followed by protracted withdrawal (WD; 2 weeks) and performed ex vivo electrophysiology using whole-cell patch clamp to study GABAergic transmission in layer V of IL pyramidal neurons. We found that WD increased frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs), whereas miniature IPSCs (mIPSCs; recorded in the presence of tetrodotoxin) were unaffected by either Dep or WD. The application of 5-HT (50 μM) increased sIPSC frequencies and amplitudes in naive and Dep rats but reduced sIPSC frequencies in WD rats. Additionally, 5-HT2A receptor antagonist M100907 and 5-HT2C receptor antagonist SB242084 reduced basal GABA release in all groups to a similar extent. The blockage of either 5-HT2A or 5-HT2C receptors in WD rats restored the impaired response to 5-HT, which then resembled responses in naive rats. Our findings expand our understanding of synaptic inhibition in the IL in AUD, indicating that antagonism of 5-HT2A and 5-HT2C receptors may restore GABAergic control over IL pyramidal neurons. Significance statementImpairment in the serotonergic modulation of GABAergic inhibition in the medial prefrontal cortex contributes to alcohol use disorder (AUD). We used a well-established rat model of AUD and ex vivo whole-cell patch-clamp electrophysiology to characterize the serotonin modulation of GABAergic transmission in layer V infralimbic (IL) pyramidal neurons in ethanol-naive, ethanol-dependent (Dep), and ethanol-withdrawn (WD) male rats. We found increased basal inhibition following WD from chronic alcohol and altered serotonin modulation. Exogenous serotonin enhanced GABAergic transmission in naive and Dep rats but reduced it in WD rats. 5-HT2A and 5-HT2C receptor blockage in WD rats restored the typical serotonin-mediated enhancement of GABAergic inhibition. Our findings expand our understanding of synaptic inhibition in the infralimbic neurons in AUD.

Future satellite communications: Satellite constellations and connectivity from space

Satellite communications is currently undergoing a massive growth, with a rapid expansion in Low Earth Orbit (LEO) networks, and a range of new satellite technologies. Until very recently, satellite communication systems and terrestrial 5/6G wireless networks have been complementary distinct entities. There is now the opportunity to bring these networks together and deliver an integrated global coverage multi-service network. Achieving this will require solving some key research challenges, and leveraging new technologies including high frequency phased-array antennas, onboard processing, dynamic beam hopping, physical layer signal processing algorithms, transmission waveforms, and adaptive inter-satellite links and routing. By integrating seamlessly with terrestrial 5/6G networks and low altitude flying access points, future satellite networks promise to deliver universal connectivity on a global scale, overcoming geographical limitations. In this special issue, we focus on the future of satellite communications, exploring topics ranging from beam hopping and design to space routing and THz satellite communications. Our aim is to shed light on the potential of these emerging technologies and their role in reshaping the landscape of global connectivity.

Functionalization of Carbon Electrode Surface Using Polyaniline and Gold Nanoparticles for Protein Immobilization

This study presents a screen-printed carbon electrode surface functionalization to immobilize proteins. The process involves the deposition of gold nanoparticles on the carbon electrode and subsequent surface modification to immobilize bovine serum albumin–fluorescein isothiocyanate conjugate (BSA-FITC). A combination of conducting polymer and gold nanoparticles was employed to enhance the electrode contact area and current transmission. The electrode surface morphology and properties were evaluated by scanning electron microscopy (SEM) and Raman spectroscopy, showing the porous polyaniline (PANI) film has been formed on the carbon electrode surface with the network of dendritic nanofibers. Gold nanoparticles were evenly distributed on the PANI film to form a nanocomposite material layer on the carbon electrode. The observed size of these gold nanoparticles was significantly smaller than those on the electrode without a PANI film. Additionally, the current transmission of this composite material layer has been verified by cyclic voltammetry (CV). The results show that the amplitude of the redox peak was doubled compared to the bare carbon electrode and gold nanoparticle-only deposited electrode. Moreover, the success of the process was verified by fluorescence and cyclic voltammetry. The fluorescent green color observed under the microscope indicated that BSA-FITC was on the electrode surface. The change of CV signal after each step verified the formation of a new layer on the electrode surface. These results are anticipated to play an important role in developing high-sensitivity immunosensors in the future.

Study Of The Hydraulic Response Of A High Permeable Breakwater Using Physical Modelling

Physical modelling tests were conducted in the wave flume of Artelia’s hydraulic laboratory to study the hydraulic response/stability of a rubble mound breakwater made with a non-standard core composed of crushed concrete blocks (tetrapod). This design carried out by EDF, is aimed at having high permeability and fits in an eco-design approach, through the reuse of existing materials already on site. Eventually, the hydraulic efficiency of three different sections were tested and compared, all sections having the same armour layer and the same main dimensions but different {core; filter} systems : core only made with crushed tetrapod, core and underlayer made with crushed tetrapod (no filter layers with rocks) and baseline design (quarry run core and rock underlayer). Several responses were studied: armour layer stability, overtopping and transmission of the structure and head loss on both sides of the structure with an inflow/outflow system in the rear side basin set up in the wave flume. This case study illustrates 1) the importance of the physical modelling approach to testing unusual structures, as part of an eco-design approach, where the use of standard design formulas does not allow to verify the hydraulic behaviour of a high permeable breakwater and 2) also shows that unconventional design can lead to satisfactory hydraulic results.

On the performance of layered transmission with optimum decoding ordering and multiuser diversity for a K-user downlink scenario

On the performance of layered transmission with optimum decoding ordering and multiuser diversity for a K-user downlink scenario

Effects of alkyl-ketene dimer on physical, mechanical and formaldehyde emission properties of particleboard produced with melamine-impregnated paper waste

ABSTRACT This study aimed to enhance the physical properties and the weak heat transmission of the core layer, which are the weak points of particleboard produced using melamine-impregnated paper waste (MIPW) as an adhesive. Alkyl-ketene dimer (AKD) and paraffin were used as water-repellent chemicals. MIPW was used as an adhesive, and no additional resin was used. As a result of this study, the samples’ physical properties improved with AKD and paraffin's existence. Moreover, it has been approved that AKD is more effective than paraffin in improving the physical properties of the particleboard because AKD improves ester bonding with hydroxyl groups of cellulose fibers. The usage of water repellents resulted in the improvement of internal bond (IB) properties. It was determined that the type and amount of water-repellent chemicals significantly affected the mechanical and physical properties and formaldehyde content of the produced particleboards, except for bending properties. Just the chemical type was found to be significantly effective on bending strength (BS) and modulus of elasticity (MOE) properties. Overall, the study findings suggested that AKD might be successfully utilized as a water-repellent chemical in particleboard manufacturing, while MIPWs used as an adhesive.

Research on Secure Physical Layer Transmission Assisted by Intelligent Reflective Surfaces

Intelligent Reflecting Surface (IRS) consists of large-scale low-cost passive reflective elements that can reflect and change the base station beam by changing the phase of the reflective units, thus enhancing the security of the physical layer of wireless communications. In the communication system, we will use the security rate to compare the confidentiality performance of a certain transmission signal. In this paper, we study the optimization problem of maximizing the security rate, and propose an alternating iteration method to decompose the problem which has more dimensions and the parameters are coupled with each other, and then design a suitable solution for each phase. Simulation results show a reduction in complexity and a greater advantage in the performance of the designed algorithm.

Transmission and nanohardness studies of ternary GaAs1-xPx layers grown from the vapor phase by heteroepitaxy

Transmission measurements in the 0.5–25-μm spectral range are performed on thin (<350-μm) GaAsP layers grown by Hydride Vapor Phase Epitaxy (HVPE) on plain (100) GaAs substrates. Comparison with calculations taking into account multiple reflections reveals the role of the surface polishing quality on the clear transmission window and the wavelength dependent losses. A measurement of a 5-mm thick epitaxially grown GaP underlines more realistic spectral limitations on the application of orientation-patterned structures based on GaP and GaAsP for nonlinear optical frequency conversion. The mid-IR cut-off wavelength for the ternary GaAsP layers is almost independent of the composition and corresponds to the same two-phonon absorption limit observed in the binary GaP. Nanohardness and Young's modulus are measured for the same samples to evaluate their compositional dependence. The nanohardness dependence on the P-content obeys a second order polynomial law with a maximum around P = 0.8. Young's modulus depends linearly on the P-content, similar to the trend observed in other ternary systems, such as InxGa1−xAs and InxGa1-xP. The evolution of the band-gap, estimated from the transmission measurements, with the composition of the ternary compounds is linear in the range of 0–0.5 for the P content. In this same range the nanohardness can be considered to be linearly proportional to the band-gap.

Genetic background determines synaptic phenotypes in Arid1b-mutant mice.

ARID1B, a chromatin remodeler, is strongly implicated in autism spectrum disorders (ASD). Two previous studies on Arid1b-mutant mice with the same exon 5 deletion in different genetic backgrounds revealed distinct synaptic phenotypes underlying the behavioral abnormalities: The first paper reported decreased inhibitory synaptic transmission in layer 5 pyramidal neurons in the medial prefrontal cortex (mPFC) region of the heterozygous Arid1b-mutant (Arid1b+/-) brain without changes in excitatory synaptic transmission. In the second paper, in contrast, we did not observe any inhibitory synaptic change in layer 5 mPFC pyramidal neurons, but instead saw decreased excitatory synaptic transmission in layer 2/3 mPFC pyramidal neurons without any inhibitory synaptic change. In the present report, we show that when we changed the genetic background of Arid1b+/- mice from C57BL/6 N to C57BL/6 J, to mimic the mutant mice of the first paper, we observed both the decreased inhibitory synaptic transmission in layer 5 mPFC pyramidal neurons reported in the first paper, and the decreased excitatory synaptic transmission in mPFC layer 2/3 pyramidal neurons reported in the second paper. These results suggest that genetic background can be a key determinant of the inhibitory synaptic phenotype in Arid1b-mutant mice while having minimal effects on the excitatory synaptic phenotype.

A physical layer security scheme for 6G wireless networks using post-quantum cryptography

The sixth generation (6G) of mobile networks is poised to revolutionize communication capabilities with its infinite-like reach. These networks will feature an ultra-dense topology, accommodating a wide range of devices, from macro devices like satellites to nano-devices integrated within the human body. However, the extensive data traffic handled by 6G networks, a significant portion of which is sensitive in nature, presents a security challenge. This paper presents the design and implementation of an encryption scheme that ensures the confidentiality of data transmission in the physical layer of 6G networks. The proposed physical layer security architecture relies on lattice cryptography, wherein each user is associated with a pair of bases (a public basis and a private basis) and a set of orthogonal sub-carriers. The encryption process involves projecting the vector of the transmitted data’s quadrature amplitude modulation (QAM) symbols onto the user’s public basis. A random error vector is then added before applying the inverse Fourier transform of the orthogonal frequency division multiplexing (OFDM) technique. The security of this encryption scheme hinges on the complexity of the closest vector problem in an integer lattice. To evaluate its efficacy, we analyze the security of our lattice-based physical layer encryption concerning the properties of the base pairs and error vectors. Our findings indicate that the proposed scheme offers satisfactory security protection against eavesdropping attacks by significantly enhancing the confidentiality of the transmitted signal. Furthermore, we assess the performance of our design through numerical experiments, demonstrating its resilience against various security attacks.

Extreme Dewetting Resistance and Improved Visible Transmission of Ag Layers Using Sub-Nanometer Ti Capping Layers.

As technology development drives the thickness of thin film depositions down into the nano regime, understanding and controlling the dewetting of thin films has become essential for many applications. The dewetting of ultra-thin Ag (9 nm) films with Ti (0.5 nm) adhesion and capping layers on glass substrates was investigated in this work. Various thin film stacks were created using magnetron sputtering and were analyzed using scanning electron microscopy/energy dispersive X-rays, Vis/IR spectrometry, and four four-point probe resistivity measurements. Upon annealing for 5 h in air at 250 °C, the addition of a 0.5 nm thick Ti capping layer reduced the dewet area by an order of magnitude. This is reflected in film resistivity, which remained 2 orders of magnitude lower than uncapped variants. This Ti/Ag/Ti structure was then deployed in a typical low-emissivity window coating structure with additional antireflective layers of AZO, resulting in a superior performance upon annealing. These results demonstrate an easy, manufacturable process that improves the longevity of devices and products containing thin Ag films.

Congestion Avoidance in TCP Based on Optimized Random Forest with Improved Random Early Detection Algorithm

Transmission control protocol (TCP) ensures that data are safely and accurately transported over the network for applications that use the transport protocol to allow reliable information delivery. Nowadays, internet usage in the network is growing and has been developing many protocols in the network layer. Congestion leads to packet loss, the high time required for data transmission in the TCP protocol transport layer for end-to-end connections is one of the biggest issues with the internet. An optimized random forest algorithm (RFA) with improved random early detection (IRED) for congestion prediction and avoidance in transport layer is proposed to overcome the drawbacks. Data are initially gathered and sent through data pre-processing to improve the data quality. For data pre-processing, KNN-based missing value imputation is applied to replace the values that are missing in raw data and [Formula: see text]-score normalization is utilized to scale the data in a certain range. Following that, congestion is predicted using an optimized RFA and whale optimization algorithm (WOA) is used to set the learning rate as efficiently as possible in order to reduce error and improve forecast accuracy. To avoid congestion, IRED method is utilized for a congestion-free network in the transport layer. Performance metrics are evaluated and compared with the existing techniques with respect to accuracy, precision, recall, specificity, and error, whose values that occur for the proposed model are 98%, 98%, 99%, 98%, and 1%. Throughput and latency are also evaluated in the proposed method to determine the performance of the network. Finally, the proposed method performs better when compared to the existing techniques and prediction, and avoidance of congestion is identified accurately in the network.

Synchronization of Analog-Discrete Chaotic Systems for Wireless Sensor Network Design

The current work is focused on studying the performance of the Pecora–Carroll synchronization technique to achieve synchronization between the analog and discrete chaos oscillators. The importance of this study is supported by the growing applications of chaotic systems for improving the security of data transmission in various communication layers, primarily on the physical layer. The hybrid analog-discrete approach of implementing chaos oscillators opens new possible communication schemes for wireless sensor network (WSN) applications. The analog implementation of chaos oscillators can benefit the simpler sensor node (SN) integration, while the discrete implementation can be used on the gateway. However, the core of such chaos-based communications is synchronizing analog and discrete chaos oscillators. This work studies two key parameters of analog-discrete chaotic synchronization: chaotic synchronization noise immunity and synchronization speed. The noise immunity study demonstrates the quality of synchronization at various noise levels, while the synchronization speed demonstrates how quickly the analog-discrete synchronization is achieved, along with how quickly the two systems diverge when synchronization is no longer present. The two studies use both simulation-based and hardware-based approaches. In the simulation case, the analog oscillator’s circuit is modeled in LTspice XVII, while in the hardware case, the circuit is implemented on the PCB. In both simulation and hardware studies, the discrete model of the oscillator is implemented in MATLAB R2023b. The studies are performed for two pairs of different chaos oscillators to widen the proposed approach application potential: the Vilnius and RC chaos oscillators. The oscillators have been selected due to their simplicity and similar dynamic behavior for model-based and electrical circuit implementation. The proposed approach also allows us to compare the synchronization of different oscillators in the analog-discrete implementation.