Additional Bits Research Articles

Toward Comprehensive Shifting Fault Tolerance for Domain-Wall Memories With PIETT

Spintronic domain-wall memories (DWMs) offer improved memory density and energy compared to conventional memories but are susceptible to shifting faults. We propose PIETT (<b>P</b>inning, <b>I</b>nsertion, <b>E</b>rasure, and <b>T</b>ranslation-fault <b>T</b>olerance) for improved misalignment correction versus the state of the art. PIETT proposes a derived error correction combined with multi-domain access approach to detect and correct a minimum of three misalignment faults after an arbitrary shift distance. Moreover, we characterize the rate of both misalignment and pinning faults in DWM nanowires and demonstrate that pinning faults are a significant concern to DWM. As such, PIETT is the first method combine correction of misalignment and pinning faults in random access DWMs. It also introduces novel PIETT Transverse Access Points (TAPs) that utilize a novel write access mode which can set/reset multiple domains in a single intrinsic operation and can store shift distance detection codes. By allowing checks between shifts of the intrinsic shift distance (<i>e.g.,</i> 3 domains), using a single TAP per nanowire expands misalignment protection and determines the needed corrective shifts to correct faults in all nanowires. Two TAPs expands misalignment protection to correct misalignment by more than one position and detects pinning by detecting different shift distances at each extremity of the nanowire. PIETT leverages knowledge of pinned nanowire locations to guide a modified SECDED ECC with one additional parity bit stored in additional parity nanowires. Thus, PIETT in TAP mode can correct unlimited, potentially multi-position, misalignment faults and either up to three pinning faults or up to two pinning faults with up to one bit-flip fault using scrubbing. PIETT provides eight to 21 orders of magnitude improvement in mean-time-to-failure with similar or better area overhead and only a 1&#x0025; system performance degradation compared to state of the art DWM misalignment correction.

Joint RIS Grouping Design Assisted Generalized Quadrature Reflection Modulation

In this paper, a novel joint reconfigurable intelligent surface (RIS) grouping design assisted generalized quadrature reflection modulation (JGD-GQRM) scheme is proposed for a single radio frequency (RF) multiple-input multiple-output (MIMO) system. In JGD-GQRM, a limited number of RIS elements are spatially grouped, and the remaining reflection patterns are utilized for joint mapping to improve the reliability of the transmission. Moreover, it maps additional information bits by full reflection passive beamforming to improve the system's spectral efficiency (SE). In addition to the optimal maximum likelihood (ML) detector that has high computational complexity, a low-complexity sequential greedy detection (SGD) for JGD-GQRM is proposed. Simulation results show that the proposed scheme can achieve better bit error rate (BER) performance than the existing reflection modulation.

Realization of Index Modulation with Intelligent Spatiotemporal Metasurfaces

Advanced wireless communication with high spectrum efficiency and energy efficiency has always fascinated humanity, especially with the explosive increase of global mobile data services. Index modulation (IM) has recently been found to be a promising technique due to the transmission of additional data bits via the indices of the available transmit entities. However, the practical implementation of IM remains a great challenge associated with complicated radio components. Herein, IM with intelligent spatiotemporal metasurfaces is experimentally demonstrated. The spatiotemporal metasurfaces provide a natural and versatile platform to achieve IM in a green and lightweight manner. The whole system is driven by a built‐in inverse‐design agent that automates spatiotemporal metasurfaces to cater to diverse application demands. In doing so, how to mitigate the inherent nonuniqueness issue and how to setup the input target from practical scenes are concretely discussed. In the microwave experiment, the spatiotemporal metasurfaces are fabricated and demonstrate the feasibility by harvesting two harmonic waves as communication channels. An intelligent electromagnetic platform that can manipulate electromagnetic waves in multidimensions is provided, meriting other numerous intelligent meta‐devices that avoid overburdening data analysis networks in smart cities of the future.

Design of High-Speed SAR ADC based on 40nm CMOS Process

In this paper, a high-speed successive approximation analog-to-digital converter is designed based on a 40 nm CMOS process. A split-capacitor Vcm-Based switching strategy is designed, which is able to keep the output common-mode voltage constant for the DAC capacitor array without using Vcm level drive, while saving half of the capacitance compared to the conventional switching strategy and greatly reducing the area consumption. It also combines the features of binary redundancy technology and non-binary redundancy technology by splitting the highest bit capacitor to the lower bit, which enables the DAC array to generate two additional redundant bits without adding other capacitors, reducing its requirements for noise and establishment accuracy; and it adopts asynchronous timing control without external clocks, which is conducive to improving the speed of SAR ADCs and reducing the design complexity. The designed SAR ADC achieves 9.83 bit effective bits, 60.9 dB signal-to-noise distortion ratio, 77.2 dB spurious-free dynamic range, 1.68 mW overall power consumption, and 18.46 fJ/conv-step superiority at a supply voltage of 1.1 V and a sampling frequency of 100 MHz through simulation.

RIS-Aided Joint Transceiver Space Shift Keying Reflection Modulation

In this letter, a reconfigurable intelligent surface-aided joint transceiver space shift keying reflection modulation (RIS-JTSSK-RM) scheme is proposed. The RIS aids the transceiver SSK modulation and inserts additional bits into the reflected phase shift of the radio frequency (RF) signal simultaneously. The design of reflection modulation constellation points and the joint mapping of transceiver antennas enhance the system’s reliability. To reduce the RIS-JTSSK-RM required computational complexity, a practical non-coherent greedy detector is proposed. In addition, we analyze the proposed system’s bit error rate (BER) performance under the optimal maximum likelihood detector. The theoretical and simulation results show that the proposed system has better BER performance.

Improving Image Compression With Adjacent Attention and Refinement Block

Recently, learned image compression algorithms have shown incredible performance compared to classic hand-crafted image codecs. Despite its considerable achievements, the fundamental disadvantage is not optimized for retaining local redundancies, particularly non-repetitive patterns, which have a detrimental influence on the reconstruction quality. This paper introduces the autoencoder-style network-based efficient image compression method, which contains three novel blocks, i.e., adjacent attention block, Gaussian merge block, and decoded image refinement block, to improve the overall image compression performance. The adjacent attention block allocates the additional bits required to capture spatial correlations (both vertical and horizontal) and effectively remove worthless information. The Gaussian merge block assists the rate-distortion optimization performance, while the decoded image refinement block improves the defects in low-resolution reconstructed images. A comprehensive ablation study analyzes and evaluates the qualitative and quantitative capabilities of the proposed model. Experimental results on two publicly available datasets reveal that our method outperforms the state-of-the-art methods on the KODAK dataset (by around 4dB and 5dB) and CLIC dataset (by about 4dB and 3dB) in terms of PSNR and MS-SSIM.

High Quality Video Frames From VVC: A Deep Neural Network Approach

In recent years, video content has become a significant contributor to Internet traffic, prompting the development of efficient codecs, such as High Efficiency Video Coding (HEVC) and Versatile Video Coding (VVC), to reduce bandwidth usage and storage requirements. However, these video coding standards still exhibit quality degradation and artifacts in the decoded frames. To address this issue, researchers have introduced several network architectures based on deep-learning algorithms; however, most of them focus on in-loop filtering, which requires additional bits to transmit filter information from the encoder to the decoder under a video-coding framework. In this paper, we propose a neural-network-based post-processing method to enhance the decoded frames. In the experimental result, the proposed model achieves a significant bitrate reduction, as measured by Bjøntegaard Delta of 4.54%, 4.13%, and 5.21% for random access (RA), low-delay (LD), and all-intra (AI) configurations, respectively, while also improving peak signal-to-noise ratio (PSNR).

Long-Block Differential Spatial Modulation

Spatial modulation (SM) can transmit additional data bits by selecting antennas and avoids synchronization and interferences among antennas. Differential SM (DSM) is a noncoherent technique of SM, but it is less bandwidth efficient than SM. This paper proposes a novel DSM scheme called long-block DSM (LB-DSM), whose block is longer than the original DSM’s. Each block of LB-DSM consists of two parts. One part is the block of the original DSM, and the other is similar to SM. With the aid of the latter part, the data rate of LB-DSM is higher than that of DSM. Besides, we propose bit mapping and low-complexity noncoherent maximum-likelihood detection for LB-DSM, by which LB-DSM is less complicated than DSM. In addition to higher bandwidth efficiency and lower decoding complexity, distance analysis and computer simulation results indicate that LB-DSM provides better error performance than DSM for 8PSK (eight-ary phase shift keying). Furthermore, the idea of LB-DSM is applied to generalized DSM (GDSM), which activates more than one transmit antenna each time. The resulting scheme, called long-block GDSM, offers better bandwidth efficiency and error performance than GDSM.

Bandwidth-Efficient Generalized Differential Spatial Modulation

Differential spatial modulation (DSM) can transmit additional data bits by selecting indexes of antennas without the pilot overhead and increasing radio frequency circuits and power consumption. DSM is extended to generalized DSM (GDSM) where more than one transmit antennas are activated each time. However, the transmission rate of the existing GDSM scheme is low. In this paper, we propose a new GDSM scheme that uses symbol interleaving on differential space-time modulation. The number of interleaving patterns is derived, and interleaving patterns with transmit diversity two are created as well. By selecting the interleaving patterns, the proposed scheme has higher data rates than the existing GDSM scheme. We also propose low-complexity detectors for both schemes. Theoretical analysis and computer simulation both show that the proposed scheme has satisfactory error performance.

A Novel Differential Chaos Shift Keying Scheme With Multidimensional Index Modulation

A new differential chaos shift keying scheme with multidimensional index modulation, referred to as MIM-DCSK scheme, is proposed in this paper. This design objective of the proposed MIM-DCSK scheme is to enhance the data rate, energy efficiency, and spectral efficiency of traditional DCSK scheme. In the proposed MIM-DCSK scheme, in addition to the information bits allocated for physical transmission, multidimensional transmission entities, namely the time slot, carrier, and Walsh code are simultaneously considered as indices to convey additional information bits, thus achieving high data rate, spectral efficiency, and energy efficiency. The theoretical bit-error-rate (BER) expressions of the MIM-DCSK scheme are derived over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. Furthermore, the data rate, complexity, spectral efficiency, and energy efficiency of the MIM-DCSK scheme are analyzed. Simulation results verify the accuracy of the theoretical analysis and illustrate the superiority of the proposed scheme. The proposed MIM-DCSK scheme is a promising solution for low-power and low-cost short-wireless communications.

Lorentz quantum computer

A theoretical model of computation is proposed based on Lorentz quantum mechanics. Besides the standard qubits, this model has an additional bit, which we call hyperbolic bit (or hybit in short). A set of basic logical gates are constructed and their universality is proved. As an application, a search algorithm is designed for this computer model and is found to be exponentially faster than Grover’s search algorithm.

Signal Vector Design for Quadrature Index Modulation

In this paper, we propose a new technique of quadrature index modulation with signal vector design (QIM-SSD), which can directly transmit a three-dimensional (3D) constellation symbol and expand an antenna index (AI) bit. The basic principle of QIM-SSD is as follows: two components of a mapped 3D signal symbol are first modulated on the upper and lower parts of transmit antennas (TAs) by two specific AI vectors with two blocks of AI bits, respectively, resulting in a space vector symbol. The remaining one component is modulated on one TA activated by the specific AI vector with one block of AI bits, then forming another space vector symbol. Furthermore, based on the resulted two space vector symbols, an additional bit is used to determine the real and imaginary parts of a complex transmit vector. The research of this paper is summarized as follows: firstly, the system model of QIM-SSD is introduced in detail. Then, the minimum Euclidean distance and the average bit error probability (BEP) are analyzed. With assumption of perfect channel estimation and maximum likelihood (ML) detection, simulation results demonstrate that the average BEP performance of QIM-SSD is better than that of the conventional QIM with three dimensional constellation and QSM at the same spectral efficiency by MATLAB simulator.

Adversarial data hiding with only one pixel

Making adversarial samples to fool deep neural network (DNN) is an emerging research direction of privacy protection, since the output of the attacker's DNN can be easily changed by the well-designed tiny perturbation added to the input vector. However, the added perturbation is meaningless. Why not embed some useful information to generate adversarial samples while integrating the functions of copyright and integrity protection of data hiding? This paper solves the problem by modifying only one pixel of the image, that is, data hiding and adversarial sample generation are achieved simultaneously by the only one modified pixel. In CIFAR-10 dataset, 11 additional bits can be embedded into the host images sized 32 × 32, and the successful rate of adversarial attack is close to the state-of-the-art works. This paper proposes a new idea to combine data hiding and adversarial sample generation, and gives a new method for privacy-preserved processing of image big data.

A novel interference signal superposition algorithm for providing secrecy to subcarrier number modulation‐based orthogonal frequency division multiplexing systems

AbstractOrthogonal Frequency Division Multiplexing with Subcarrier Number Modulation (OFDM‐SNM) is a transmission scheme that aims to convey additional data bits by exploiting the number of active subcarriers. Even though OFDM‐SNM creates many advantages, such as low bit error rate (BER), high spectral efficiency, and high reliability, it suffers from the security vulnerabilities against eavesdroppers and malicious wire‐tappers. The reason why OFDM‐SNM is vulnerable against security threats is that the nature of subcarrier number‐based additional data transmission differs from the conventional data modulation techniques, which makes the existing physical layer security (PLS) applications to be inapplicable for OFDM‐SNM. Therefore, novel PLS techniques must be developed for OFDM‐SNM to secure the data that is transmitted by exploiting the number of subcarriers. In this paper, a novel interference signal superposition security algorithm for OFDM‐SNM is proposed at the physical level to overcome its security vulnerabilities. The proposed security application aims to provide the data secrecy by embedding an artificial interference signal into the data that are meant to be conveyed by the active subcarriers. This artificial interference signal is created by exploiting the channel state information of the legitimate user, and deliberately included into the transmitted data to create a confusion for those who try to infiltrate the communication system, such as eavesdroppers or malicious wire‐tappers. In this paper, the transmission of data for both the legitimate user and eavesdropper is operated by M‐ary PSK/QAM modulation over a Rayleigh fading channel. The theoretical calculations and simulation results prove that the proposed security application for OFDM‐SNM is a strong candidate to provide the security requirements of such cases in future wireless networks, where providing data secrecy is among the top priorities.

Reordered Amplitude Phase Shift Keying Aided Differential Spatial Modulation: DFDD-Based Low-Complexity Detector and Performance Analysis Over Fading Channels

Differential spatial modulation (DSM) is a multiple input multiple output (MIMO) wireless transmission technique that achieves additional data bit transmission by utilizing antenna activation indexes. Combined with amplitude phase shift keying (APSK) constellations, the spectrum efficiency of DSM system can be further improved. However, the theoretically optimal maximum likelihood (ML) detection suffers from a high complexity that grows exponentially with the number of transmit antennas (TAs). Besides, the imperfect channel state information in fast fading channels leads to a severe deterioration of the detection performance. To address these problems, we propose a novel transmission scheme named reordered amplitude phase shift keying aided differential spatial modulation (RAPSK-DSM) and its low-complexity decision-feedback differential detection (DFDD) based detection algorithm. The proposed RAPSK-DSM scheme provides a better solution for addressing the error propagation problem and its detector utilizes the preceding channel gain vectors from previous detection results to mitigate the performance loss caused by time-selective channel fading. Furthermore, by decomposing and pre-computing the detection process, the complexity of proposed detector is effectively reduced due to the avoidance of redundant computations. Numerical analyses and simulation results show that the proposed RAPSK-DSM system is able to achieve substantial bit error rate (BER) performance improvement under fast fading channel conditions at the expense of low complexity.

A High-Capacity Reversible Data-Hiding Scheme for Medical Image Transmission Using Modified Elias Gamma Encoding

Reversible data hiding (RDH) is a recently emerged research domain in the field of information security domain with broad applications in medical images and meta-data handling in the cloud. The amount of data required to handle the healthcare sector has exponentially increased due to the increase in the population. Medical images and various reports such as discharge summaries and diagnosis reports are the most common data in the healthcare sector. The RDH schemes are widely explored to embed the medical reports in the medical image instead of sending them as separate files. The receiver can extract the clinical reports and recover the original medical image for further diagnosis. This manuscript proposes an approach that uses a new lossless compression-based RDH scheme that creates vacant room for data hiding. The proposed scheme uses run-length encoding and a modified Elias gamma encoding scheme on higher-order bit planes for lossless compression. The conventional Elias gamma encoding process is modified in the proposed method to embed some additional data bits during the encoding process itself. The revised approach ensures a high embedding rate and lossless recovery of medical images at the receiver side. The experimental study is conducted on both natural images and medical images. The average embedding rate from the proposed scheme for the medical images is 0.75 bits per pixel. The scheme achieved a 0 bit error rate during image recovery and data extraction. The experimental study shows that the newly introduced scheme performs better when compared with the existing RDH schemes.

Reflector Antennas Characterization and Diagnostics Using a Single Set of Far-Field Phaseless Data and Crosswords-Like Processing

We introduce and discuss a new approach to the phase retrieval of fields radiated by continuous aperture sources having a circular support, which is of interest in many applications including the detection of shape deformations on reflector antennas. The approach is based on a decomposition of the actual 2-D problem into a number of 1-D phase retrieval problems along diameters and concentric rings of the visible part of the spectrum. In particular, the 1-D problems are effectively solved by using the spectral factorization method, while discrimination arguments at the crossing points allows to complete the retrieval of the 2-D complex field. The proposed procedure, which just requires a single set of far field amplitudes, takes advantage from up to now unexplored field properties and it is assessed in terms of reflector aperture fields.

A Novel Hypercube-Based Heuristic for Quantum Boolean Circuit Synthesis

Quantum computation has extraordinary capabilities for solving complicated problems. As quantum computations are reversible by nature, reversible circuits are important for the development of quantum computation techniques. Designing an effective and efficient method for synthesizing reversible circuits to reduce costs and stabilize circuit efficiency is crucial. The traditional synthesis methods of solving reversible circuits focus on the conversion efficiency rather than discussing the properties of the reversible function. Thus, this paper aims to propose a novel synthesis method that directly and efficiently optimizes reversible circuit synthesis with the properties of the reversible circuit. The proposed method converts the reversible function into a hypercube, allowing visual observations of the overall circuit. Two new indicators, the adjacent Hamming distance (AHD) and total cycle distance (TCD), aid in effective decision-making, generating shorter circuits. Furthermore, we use the generalized Toffoli gate set, which without requiring any additional ancilla bits and has applications in error correction and fault tolerance. The experimental results show that our method can find better solutions than traditional methods, significantly reducing the gate count, while the hypercube assists in synthesizing the reversible circuit.

Simple Clock Drift Estimation and Compensation for Packet-Level Index Modulation and Its Implementation in LoRaWAN

Low-power wide-area network (LPWAN), which includes the long-range wide-area network (LoRaWAN) protocol, is an enabling technology that satisfy low power consumption and long-range communication. In many applications of LPWAN, an end node (EN) transmits data at regular intervals. Based on this, we had previously proposed the concept of packet-level index modulation (PLIM) to increase the number of information bits transmitted by one data packet. In PLIM, the generation interval between two consecutive packets is split into multiple time slots. Each EN transmits its packet in a specific combination of time slot and frequency channel, which represents the index, to convey additional information bits. To retrieve additional information, the gateway (GW) detects the time slot in which the data packet is being transmitted. Therefore, accurate synchronization between EN and GW is essential. However, clock drift occurs due to the inexpensive real-time clock oscillator on each EN, which results in timing misalignment between each node and the GW. This article proposes a simple clock drift estimation and compensation method for the PLIM. An experimental measurement is performed to model the clock drift. The numerical results obtained using the clock drift model show that it can accurately detect the time slot index under the influence of clock drift. Furthermore, PLIM is implemented on a commercial LoRaWAN node and GW to demonstrate its practicability.

Communication-Efficient Distributed SGD Using Random Access for Over-the-Air Computation

In this paper, we study communication-efficient distributed stochastic gradient descent (SGD) with data sets of users distributed over a certain area and communicating through wireless channels. Since the time for one iteration in the proposed approach is independent of the number of users, it is well-suited to scalable distributed SGD. Furthermore, since the proposed approach is based on preamble-based random access, which is widely adopted for machine-type communication (MTC), it can be easily employed for training models with a large number of devices where MTC is used for their connectivity. For fading channel, we show that noncoherent combining can be used. As a result, no channel state information (CSI) estimation is required. For over-the-air computation, the proposed approach takes advantage of random access, where the access probability is to encode the norm of local gradient vector (without using any additional bits) and the preamble is to encode the quantized normalized gradient vector. From analysis and simulation results, we can confirm that the proposed approach is not only scalable, but also provides improved performance as the number of devices increases. From analysis and simulation results, we can confirm that the proposed approach is not only scalable, but also provides improved performance as the number of devices increases.