Maximum Bit Research Articles

Minimize BER without CSI for dynamic RIS-assisted wireless broadcast communication systems

This paper studies a dynamic reconfigurable intelligent surface (RIS)-assisted broadcast communication system where a transmitter broadcasts information to multiple receivers with time-varying locations via a RIS. The goal is to minimize the maximum bit error rate (BER) at the receivers by optimizing RIS phase shifts, subject to a given discrete phase shift constraint. Unlike most existing works where channel state information (CSI) is required, only location information of the receivers is needed in our work, due to the great challenge of instantaneous CSI estimation in RIS-assisted communications and the reason that statistical CSI does not apply to the dynamic scenario. The involved optimization problem is hard to tackle, because the BERs at the receivers cannot be calculated by classical CSI-dependent analytical expressions for lack of CSI and exhaustive searching is computationally prohibitive to achieve the optimal discrete phase shifts. To address this issue, a deep reinforcement learning (DRL) approach is proposed to solve the problem by reformulating the optimization problem as a Markov decision process (MDP), where the BERs are measured by the Monte Carlo method. Furthermore, to tackle the issue of the high-dimensional action space in the MDP, a novel action-composition based proximal policy optimization (PPO) algorithm is proposed to solve the MDP. Simulation results verify the effectiveness of the proposed PPO-based DRL approach.

Subthreshold read operations in 3D PCM: 1S1R device modeling and memory array analysis

3-D phase change memory (PCM) is one of the most promising next-generation nonvolatile memory, and the subthreshold sensing strategy can effectively improve its limited endurance. In this study, we propose a one-selector-one-resistor (1S1R) model with Monte Carlo (MC) function and provide array configurations for the worst case and the maximum bit line voltage (VBL-max), respectively. Based on these, the read window margin (RWM) is evaluated with various array sizes, OTS threshold voltage variations (σvar), and bias voltages (VBias). Our results reveal that the RWM increases as the VBL approaches the VBL-max. Larger arrays lead to an increased leakage current difference, while larger σvar values result in decreased cell current difference and VBL-max. The decrease in VBL-max further deteriorates the RWM. Additionally, we analyze the optimal VBias for 2-deck arrays achieves a 7% reduction in leakage energy consumption and a 22.6% increase in RWM compared to the V/2 bias. The optimal VBias depends on OTS devices and array sizes.

Lamb-Waves-Based Sparse Distributed Penetrating Communication via Phase-Position Modulation for Enclosed Metal Structures

Sensor nodes have been widely used for mechanical equipment condition monitoring, especially for enclosed metal structures. In these cases, it is important to achieve communication between the sensor nodes inside the enclosed metal structures and the outside receiver node. Conventional wired communication using cables will affect the structural integrity, and wireless communication using electromagnetic waves will be shielded by metal structures, so neither is desirable. Motivated by these issues, this study proposes a Lamb waves-based sparse distributed penetrating communication (SDPC) system using the propagation characteristics of Lamb waves considered harmful in previous studies to accomplish wireless simultaneous data communication. Combining phase shift keying and pulse position modulation mechanisms, a phase-position modulation (P-PM) technology is proposed to improve the communication rate. To overcome the intersymbol interference (ISI) problem caused by the propagation characteristics of Lamb waves, a phase-position sparse reconstruction (P-PSR) strategy is proposed for demodulation, which is more convenient and accurate compared with the conventional cross-correlation method. It should be noted that the maximum bit rate without bit error reaches 830.48 kbps via P-PM parameter optimization, which is 8.3 times higher than that of on-off keying modulation approach under the same experimental conditions. Finally, distributed communication experiments and simulations further verify the high accuracy, efficiency and strong robustness of the proposed SDPC system, which can meet the communication requirements of enclosed metal structures.

New Wind and Pressure-resistant Structural Design and Static Simulation Analysis of Continuous Greenhouse

To improve the wind and snow resistance of the continuous round-arch greenhouse skeleton structures, a new wind and pressure-resistant continuous greenhouse with arch spars and diagonal ties is designed in this study. By increasing the number of secondary arches, arch spars, and diagonal ties, and optimizing the traditional spars, this skeleton structure not only improves the snow pressure resistance of arch bars but also enhances the resistance to wind loads. Taking wind load and snow load in the Hangzhou area of Zhejiang province as an example, ANSYS workbench software was used to analyze and calculate the stress and displacement of this shed, and it was found that the maximum stress value could reach 88.641 MPa and the maximum bit amount was 10.316 mm. Compared with the traditional plastic continuous shed, the optimized structure of wind and pressure-resistant continuous shed can effectively reduce the arch displacement and enhance the stability of the structure.

Miniaturized Antenna Array-Based Novel Metamaterial Technology for Reconfigurable MIMO Systems.

In this work, a highly miniaturized microstrip antenna array based on two elements is proposed for multiple inputs multiple outputs (MIMO) application systems at sub-6 GHz frequency bands. The antenna is structured from a meander line in conjugate with an interdigital capacitor when excited through the monopole basic antenna. The proposed antenna elements are separated with a Minkowski factor-shaped metamaterial (MTM) column to achieve a separation distance (D) of 0.08λ at 3 GHz when printed on an FR-4 substrate. Later on, the antenna performance in terms of bandwidth and gain is controlled using a photonic process based on optical active switches based on light-dependent resistances (LDR). Therefore, the reconfiguration complexity with such a technique can be eliminated significantly without the need for a biasing circuit. The antenna design was conducted through several parametric studies to arrive at the optimal design that realizes the frequency bandwidth between 3 and 5.5 GHz with a maximum gain of about 4.5 dBi when all LDR terminals are off. For a wireless channel performance study-based massive MIMO environment, the proposed antenna is suitable to be configured in arrays of 64 × 64 elements. From this study, it was found the maximum bit error rate (BER) does not exceed 0.15 with a channel capacity (CC) of 2 Gbps. For validation, the antenna was fabricated based on two elements and tested experimentally. Finally, it was revealed that the measured results agree very well with simulations after comparing the theoretical calculations with the measured data.

Performance study of HF communication using NOMA over narrowband HF channel

AbstractHigh frequency systems (HF) are still used in many communication applications. Data can be sent for hundreds of kilometers at a low power cost with only one drawback, low bitrate. To increase the bitrate, several methods were reported using the single‐Tone modulation with 24 kHz bandwidth, but still not practical in real‐time applications because, the 24 kHz is unavailable due to the instability of the ionosphere layer. In this work, we propose a structured method built on the Non‐Orthogonal Multiple Access technique (NOMA) to increase the bit rate per HF narrowband channel. To increase the data rate, two parts of the data are divided and sent to one user over two different power levels. We use the NOMA technique on the receiver's side to recognize the two parts of data. The results show a significant improvement (up to 45%) using NOMA in narrowband 3 kHz channels. The bit rate at the receiver has increased up to 200 Kb/s concerning, while the maximum bit rate recorded by conventional methods used in previous studies is 138 Kb/s. The system is built on the SDR platform and tested in multiple channels, weather, and power conditions in real‐time experiments to validate its reliability.

Key management scheme of distributed IoT devices based on blockchains

AbstractWith the rapid development of Internet of Things devices and communication technology, the number of devices connected to the Internet of Things is growing exponentially. However, in the context of the rapid increase in the number of devices, data security issues such as data leakage and data tampering also follow. Therefore, communication security between devices is particularly important. However, in the traditional network environment, the identity authentication and information encryption methods to ensure communication security mostly adopt centralized network structure, relying on the central equipment to manage the access edge equipment. However, due to the heterogeneity of IoT devices and limited resources, the traditional centralized management scheme does not fully comply with the IoT system. In order to solve the above problems, this paper proposes a blockchain distributed IoT device key management scheme under the blockchain technology framework, which proposes a blockchain based distributed IoT architecture, and designs a hash chain based identity authentication scheme and a key distribution scheme based on network security coding on the basis of this architecture. Because blockchain technology has the characteristics of openness, immutability, traceability and fault tolerance, it can ensure the privacy of data transmission in the IoT scene, thus providing a secure communication environment. In this paper, the performance indexes related to the scheme are evaluated, and the experimental analysis confirms the efficiency and scalability of the proposed scheme.

SOA-MZI Differential Transformation Approach Applied on Simultaneous Electro-Optical Mixing

We experimentally incubate a ground-breaking design, for the first time, of concurrent electro-optical semiconductor optical amplifier Mach–Zehnder interferometer mixing (SOA-MZI) based on a differential transformation methodology. Projecting the simultaneous electro-optical mixing system and improving its efficiency and quality achievement in optical and electrical features is a crucial task due to the characteristics of an optical pulse source (OPS) operating with a repetition rate of f= 58.5 GHz and a pulse width duration of 1 picosecond (ps). The resultant of the contemporaneous electro-optical mixing exhibits exceptional passive power stability, reaching 0.8% RMS over a two-hour period. Furthermore, when the optical bandpass filter is controlled at the data wavelength of 1540 nm, we achieve up to 30 dBm of the overall mean output power with an optical conversion gain of 46 dB and an exceptionally high optical signal-to-noise ratio reaching 80 dB. Using orthogonal frequency division multiplexing (OFDM) signals, each data subcarrier is modulated using 128 quadratic amplitude modulation (128-QAM) at carrier frequencies fk and simultaneously up-mixed to high aim frequencies nf±fk at the SOA-MZI output. Additionally, the resulting OFDM_128-QAM up-mixed signal is examined using the specifications for the error vector magnitudes (EVMs) and the electrical conversion gains (ECGs). The SOA-MZI mixing experiment can handle high frequencies up to 120 GHz. Positive ECGs are followed by a sharp reduction over the entire band of the aim frequencies. The highest frequency range achieved during the realistic investigation is shown at 2f+f4= 120 GHz, where the EVM reaches 8% with a symbol rate of 15 GSymb/s. Furthermore, the concurrent OFDM_128-QAM up-mixed signal achieves an absolute maximum bit rate of 80.4 Gbit/s. The investigation into the simultaneous electro-optical mixing regime is finally supported by unmatched characterization improvements.

Integration of Raspberry Pi and antennas for multiplexing digital signals over a fiber optical communication system

A Fiber Optical Communication System (FOCS) is used to experimentally demonstrate the transmission of multi-channel information of two High Definition (HD) video signals and 18 digital TV channels. These signals are supplied using commercial Raspberry Pi boards and digital TV Antennas, respectively. Both digital signals and lightwaves of a couple of Distributed Feedback (DFB) lasers with wavelengths located at 1547.5 and 1552.5 nm interact with two Mach-Zehnder Intensity Modulators (MZ-IM). The resulting modulated optical signals from each modulator are combined by using an optical coupler. The combined optical field is amplified and transmitted through 30 km of single-mode optical fiber. To demultiplex the combined optical signals, a bandpass optical filter is used, then a PIN-photodetector is connected to recover HD video signals and the 18 digital TV channels. The measured electrical spectrum of the received signals shows that the transmission is performed without interference and the multi-channel information is successfully received in an HD display. The use of wavelengths with linewidths of 10 MHz and an optical fiber with a chromatic dispersion of 17 ps/nm-km allows for a maximum bit rate of approximately 11 Gbps to be achieved numerically. This result guarantees that HD video signals can be experimentally transmitted successfully with Bit Error Rate (BER) values between 10-6 and 10-15 when the optical power of lasers is tuned between 7 and 9 dBm.

Unequal channel spacing 8×5Gbps optical system utilizing different signal representations.

Data representations are important to communication networks; they convert the data bits into a signal form, which affects the system capacity, maximum bit rate, transmission distance, and different linear and nonlinear impairments. In this paper, we propose non-return-to-zero (NRZ), chirped NRZ, duobinary, and duobinary return-to-zero (DRZ) data representations with eight dense wavelength division multiplexing channels for transmitting a 5Gbps data rate through a 250km fiber length. The results of the simulation design are calculated at different equal and unequal channel spacings, and the quality factor is measured over a wide range of optical power. For equal channel spacing, the DRZ has a preferable performance with a 28.40 quality factor at 18dBm threshold power, and the chirped NRZ has a preferable performance with a 26.06 quality factor at 12dBm threshold power. For unequal channel spacing, the DRZ has a 25.76 quality factor at 17dBm threshold power, and the NRZ has a 25.06 quality factor at 10dBm threshold power.

Study on Temperature and Water Turbulence Impact on Saline Water-Based Wireless Optical Communication

Underwater wireless optical communication (UWOC) is a promising solution for Gb/s rate and long-distance underwater communication. However, random changes in the local temperature and salinity of seawater have caused different refractive indices of ocean water. This study investigated the UWOC system in different saline water while simultaneously changing the temperature and water flow. A maximum bit error rate (BER) of 4.851 × 10−6 was measured at −7.41 dBm in 3 m of 45.56 g/L saline water. By changing the temperature to 30 °C, the bit error rate (BER) value reached 5.12 × 10−6 in the saline water. On the other hand, water flow was generated in various types of water salinity to compare simultaneous environmental effects in the UWOC system. In 45.56 g/L of saline water with water flow, the UWOC system was still capable of reaching a BER value of 4 × 10−4.

Load Balancing Control Algorithm of Internet of Things Link Based on Non-Parametric Regression Model

In order to solve the problems of poor channel balance control ability and unable to effectively reduce the output bit error rate in the traditional Internet of things link load balance control methods, a new Internet of things (IoT) link load balance control algorithm based on non-parametric regression model is proposed in this paper. The transmission model of IoT link channel is constructed, and the sparse random cluster analysis method is used to extract the load characteristics of IoT link. According to the load feature extraction results, through the estimated regression function of known data features, a non-parametric regression model is constructed, and the fuzzy cyclic iterative control is used to realize the load balancing control of the Internet of things link. The experimental results show that this method has strong channel balance control ability, low output bit error rate, the maximum average link utilisation can reach 1, and the maximum output bit error rate is only 102, which improves the stability of the Internet of things.

A Novel Revesible Data Hiding based on Improved Pixel Value Ordering Method

Reversible data hiding based on the preservationof sorted pixel value ordering (PVO) technique has beenresearched and expanded recently due to its high embeddingcapacity and good image quality. secret data is always embedded in the largest or smallest pixel of the sub-block. Thus,each sub-block will embed two bits. The more blocks an imagehas, the higher the embedding potential. In this paper, to havemore sub-blocks, the paper divides the image into sub-blockswith 3 pixels and embeds 2 bits in the maximum value and1 bit in the minimum value. Therefore, each sub-block of theproposed embedding scheme is able to hide three bits insteadof the two bits as in the original scheme. The experimentalresults also show that the proposed scheme has a significantlyhigher embedding capacity.

Performance Analyses of Photonic-Crystal Surface-Emitting Laser: Toward High-Speed Optical Communication

This study conducts comprehensive performance analyses of a commercial photonic-crystal surface-emitting laser (PCSEL) via small-signal measurement and the bit-error-rate test. Meanwhile, the radio frequency characteristics of the PCSEL are unveiled for the first time. Compared to the vertical-cavity surface-emitting lasers, the PCSEL shows great potential for a broader optical bandwidth that is benefited from the high optical-confinement factor. A maximum bandwidth of around 2.32 GHz is experimentally observed when the PCSEL was biased at 340 mA. Moreover, a theoretical calculation was applied to shed light on the characteristics of the small-signal measurement, providing a deep insight into the corresponding intrinsic response model. The signal transmission capability of the PCSEL was investigated as well. The maximum bit rate and corresponding rise time transmitted at 500 Mbps are 1.2 Gbps and 186.16 ps, respectively. Thus, a high-speed PCSEL can be realised with a shrunk form factor, serving as a promising candidate for the next-generation light sources in high-speed optical communication.

Encoding information in the mutual coherence of spatially separated light beams.

Coherence has been used as a resource for optical communications since its earliest days. It is widely used for the multiplexing of data, but not for the encoding of data. Here we introduce a coding scheme, which we call mutual coherence coding, to encode information in the mutual coherence of spatially separated light beams. We describe its implementation and analyze its performance by deriving the relevant figures of merit (signal-to-noise ratio, maximum bit-rate, and spectral efficiency) with respect to the number of transmitted beams. Mutual coherence coding yields a quadratic scaling of the number of transmitted signals with the number of employed light beams, which might have benefits for cryptography and data security.

Bio-inspired vibrational wireless underground communication system

The internet of the underground things (IoUT) is an emerging field that concerns connected underground sensing nodes and can find applications in various fields such as geotechnical engineering, precision agriculture, and search and rescue operations. The complex underground environment and multiphase nature of the soil pose challenges to wireless underground communication. Most existing studies on wireless underground communication focus on the use of electromagnetic waves. However, as a highly lossy material for electromagnetic waves, soil can limit the range and reliability of data transmission. Inspired by subterranean animals that rely on vibrations or seismic waves for underground communication, the prototype system developed in this study is based on vibration. This system includes a bio-inspired vibrating source, a micro-electromechanical system (MEMS) accelerometer, a micro-controller, and a set of algorithms for encoding and decoding information. Specifically, the mole rats-inspired source is small in size, low in cost, and energy-efficient. An on-off-keying decoding algorithm enhanced with an error-correction algorithm is found to be robust in transmitting textual and imaginary information. With the current design, a maximum transmission bit rate of 16–17 bits per second and a transmission distance of 80 cm can be achieved. The bit error ratio is as low as 0.1%, demonstrating the robustness of the algorithms. The performance of the developed system shows that seismic waves produced by vibration can be used as an information carrier and can potentially be implemented in the IoUT.

Experimental Validation of a Chaotic Jerk Circuit Based True Random Number Generator

A method for true random number generation by directly sampling a high frequency chaotic jerk circuit is explored. A method for determination of the maximum Lyapunov exponent, and thus the maximum bit rate for true random number generation, of the jerk system of interest is shown. The system is tested over a wide range of sampling parameters in order to simulate possible hardware configurations. The system is then implemented in high speed electronics on a small printed circuit board to verify its performance over the chosen parameters. The resulting circuit is well suited for random number generation due to its high dynamic complexity, long term aperiodicity, and extreme sensitivity to initial conditions. This system passes the Dieharder RNG test suite at 3.125 Mbps.

Information Steganography Technology of Optical Communication Sensor Network Based on Virtual Reality Technology

In order to solve the problems of narrow object orientation and insufficient visual rendering ability of the optical communication network experimental system, the author proposes a multithreaded scheduling using virtual reality, and the experimental system design method of optical communication network with multichannel serial port design is proposed. The system builds the overall structure model of the optical communication network experimental system in the virtual reality environment, and uses the PCI bus technology to build the transmission channel model of the optical communication network, the basic entity object of the optical communication network experimental system is constructed, and the multithread scheduling method is used to process the local information of the experimental system. The result obtained is as follows: The experimental system of optical communication network designed by the author’s method, the optical communication transmission bit error rate is reduced by about 30%, the time overhead is saved by about 60%, and the memory overhead is saved by about 50%, which is superior. Using the author’s method, the maximum bit error rate is about 22%, while the maximum bit error rate of traditional method 1 is about 43%, and the maximum bit error rate of traditional method 2 is about 70%. It is proven that the visual simulation effect of the optical communication network experimental system is good, the reliability and stability of the optical communication network are improved, and the communication transmission error is reduced.

Reconfigurable and Dynamically Transformable In-Cache-MPUF System With True Randomness Based on the SOT-MRAM

In this paper, we present a reconfigurable Physically Unclonable Functions (PUF) based on the Spin-Orbit-Torque Magnetic Random-Access Memory (SOT-MRAM), which exploits thermal noise as the true dynamic entropy source. Therefore, the MRAM cells could be configured to random final states with stochastic switching mechanism. The proposed PUF is constructed and reconfigured by combining the small-capacity true random number generator (TRNG) and high-reliability secure hash algorithm (SHA-512), realizing the dynamic transformation between SOT-MRAM based last level cache and PUF (In-Cache-MPUF). Thanks to the full reconfigurability and the high endurance of SOT-MRAM, the proposed In-Cache-MPUF can achieve <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{\textbf {14}}$ </tex-math></inline-formula> maximum PUF bits per cell, which has greatly motivated the implementations compared with the traditional weak PUFs utilizing the static entropy source of process variations. The Monte-Carlo simulation results using 40 nm technology and a compact MTJ model show that the proposed PUF has desirable randomness as the digitized bit streams passing all the NIST tests, achieving 50.0428% uniqueness as well as 49.9236% uniformity. It also shows comparable reliability to the state-of-the-art works: a maximum bit error rate of 0.14% and 0.12% at 100 °C and 0.9 V, respectively. In addition, the system level performance is tested and validated by gem5.

The influence of aluminum nanoparticles on the laser ablation characteristics of hydroxylamine nitrate-based liquid propellants

Hydroxylamine nitrate is a nontoxic green energetic propellant that has a high energy density and wide application prospects in the field of aerospace propulsion. Here, the laser ablation and propulsion properties of hydroxylamine nitrate-based propellants doped with aluminum nanoparticles were studied. The results showed a significant improvement in the laser absorption properties of hydroxylamine nitrate doped with aluminum nanoparticles. The maximum absorption rate increased by more than 80%, while the absorption depth decreased considerably with a minimum of 277 μm. The sputtering behavior also weakened during laser ablation, and the impulse of hydroxylamine nitrate could be enhanced by doping aluminum nanoparticles. With the 0.7wt% mass fraction of aluminum nanoparticles, a maximum impulse bit of 57.55 μN·s at 90 mJ laser energy. This is led to a maximum energy conversion efficiency of 218.1% and an enhancement of the kinetic energy of the hydroxylamine nitrate-based propellant of 56% with laser energy of 25 mJ. Compared with ordinary liquid propellants, doped samples have better propulsion performance.