Bit Length Research Articles

Resource allocation and passive beamforming for IRS‐assisted short packet systems

AbstractThis paper investigates an intelligent reflecting surface (IRS) assisted downlink short packet transmission system, where an access point sends short packets to multiple devices with the help of an IRS. Specifically, a performance comparison between the frequency division multiple access and time division multiple access is conducted for the considered system, from the perspective of average age of information (AoI). To minimize the maximum average AoI among all devices, the resource allocation and passive beamforming are jointly optimized. However, the formulated problem is difficult to solve due to the non‐convex objective function and coupled variables. Thus, an alternating optimization based algorithm is proposed by exploiting the semidefinite relaxation and bisection search techniques. Simulation results show that time division multiple access can achieve lower AoI by exploiting the time‐selective passive beamforming of IRS for maximizing the signal to noise ratio of each device consecutively. Moreover, it also shows that as the length of information bits becomes sufficiently large as compared to the available bandwidth, the proposed frequency division multiple access transmission scheme becomes more favourable due to more flexible power allocation.

A Lightweight Image Cryptosystem for Cloud-Assisted Internet of Things

Cloud computing and the increasing popularity of 5G have greatly increased the application of images on Internet of Things (IoT) devices. The storage of images on an untrusted cloud has high security and privacy risks. Several lightweight cryptosystems have been proposed in the literature as appropriate for resource-constrained IoT devices. These existing lightweight cryptosystems are, however, not only at the risk of compromising the integrity and security of the data but also, due to the use of substitution boxes (S-boxes), require more memory space for their implementation. In this paper, a secure lightweight cryptography algorithm, that eliminates the use of an S-box, has been proposed. An algorithm termed Enc, that accepts a block of size n divides the block into L n R bits of equal length and outputs the encrypted block as follows: E=L⨂R⨁R, where ⨂ and ⨁ are exclusive-or and concatenation operators, respectively, was created. A hash result, hasR=SHA256P⨁K, was obtained, where SHA256, P, and K are the Secure Hash Algorithm (SHA−256), the encryption key, and plain image, respectively. A seed, S, generated from enchash=Enchashenc,K, where hashenc is the first n bits of hasR, was used to generate a random image, Rim. An intermediate image, intimage=Rim⨂P, and cipher image, C=Encintimage,K, were obtained. The proposed scheme was evaluated for encryption quality, decryption quality, system sensitivity, and statistical analyses using various security metrics. The results of the evaluation showed that the proposed scheme has excellent encryption and decryption qualities that are very sensitive to changes in both key and plain images, and resistance to various statistical attacks alongside other security attacks. Based on the result of the security evaluation of the proposed cryptosystem termed Hash XOR Permutation (HXP), the study concluded that the security of the cryptography algorithm can still be maintained without the use of a substitution box.

Encryption of Medical Image Based on Cascaded Design of AES Block Algorithm and Chaotic Map

Security concerns in the transfer of medical images have drawn a lot of attention to the topic of medical picture encryption as of late. Furthermore, recent events have brought attention to the fact that medical photographs are constantly being produced and circulated online, necessitating safeguards against their inappropriate use. To improve the design of the AES algorithm standard for medical picture encryption, this research presents several new criteria. It was created so that needs for higher levels of safety and higher levels of performance could be met. First, the pixels in the image are diffused to randomly mix them up and disperse them all over the screen. Rather than using rounds, the suggested technique utilizes a cascaded-looking composition of F-functions in a quadrate architecture. The proposed F-function architecture is a three-input, three-output Type-3 AES-Feistel network with additional integer parameters representing the subkeys in use. The suggested system makes use of the AES block cipher as a function on a Type-3 AES-Feistel network. Blocks in the proposed system are 896 bits in length, whereas keys are 128 bits. The production of subkeys is encrypted using a chain of E8- algorithms. The necessary subkeys are then generated with a recursion. The results are reviewed to verify that the new layout improves the security of the AES block cipher when used to encrypt medical images in a computer system.

Actuation mechanism of a nanoscale drilling rig based on nested carbon nanotubes.

With the increasing emphasis on health and the continuous improvement of medical standards, more and more micro/nano devices are being used in the medical field. However, the existing micro/nano devices cannot effectively solve various problems encountered in medical processes and achieve specific therapeutic effects. Based on this, this article designs a new type of nanoscale drilling rig. The nanoscale drilling rig is composed of double-layer nested carbon nanotubes with multiple electrodes, and is powered by an external power source, making it easy to perform long-term surgery in the human body. Through coding strategies, we can adjust the surface charge density and distribution of the nanoscale drilling rig, thereby controlling its periodical rotation and achieving precise medical treatment. In addition, in order to control the length of the nanoscale drill bit, meet the treatment needs of different parts of the human body, and reduce damage to the human body, we have designed a structure of ion electric double layers so that the drill bit can be fixed in different positions, reducing the risk of treatment to a certain extent. This drilling rig enriches the functions of micro/nano devices, which is beneficial for the development of the medical industry.

The bottomhole stress field analysis and the rate of penetration enhancement mechanism of a new type of central-grooved single-cone/multi-blade hybrid bit for deep well drilling

In this work, a high efficiency rock-breaking idea of forming an isolated rock column in the center of the deep bottomhole, that is, a convex-stepped bottomhole and a new type of central-grooved single-cone/multi-blade hybrid bit (CSMHB) are proposed due to the problems of poor drillability of rock, low efficiency of rock breaking at the center of bit and low rate of penetration (ROP) in the deep hard formation drilling. Based on the poroelasticity theory, a numerical simulation model of the stress field of convex-stepped bottomhole is established, and the dynamic changes of the stress field of convex-stepped bottomhole with time are analyzed. Meanwhile the rock strength failure of the convex-stepped bottomhole under the stress field is analyzed based on the three-dimensional Coulomb criterion, which preliminarily reveals the ROP enhancement mechanism of the CSMHB. The research shows that after the convex-stepped bottomhole is opened, the convex area of the bottomhole is subjected to tensile stress in the circumferential, radial and axial directions. In the bottomhole area broke by PDC cutting structure, the part near the central rock column is also subjected to tensile stress in the circumferential, radial and axial directions, while the other area is subjected to compressive stress. The action range of tensile stress and the damage range of the central rock column at the bottomhole expand with the increase of the indent length and diameter of the single-cone bit respectively. The average effective stress and damage function at the center of bottomhole decrease with the increase of the indent length and diameter of the single-cone bit respectively.

Convolutional Neural Network-Based Media Noise Prediction and Equalization for TDMR Turbo-Detection With Write/Read TMR

This article considers a turbo-detection system that includes a convolutional neural network (CNN)-based equalizer, a Bahl-Cocke-Jelinek-Raviv (BCJR) trellis detector, a CNN-based media noise predictor (MNP), and a low-density parity-check (LDPC) channel decoder for two-dimensional magnetic recording (TDMR) in the presence of track misregistration (TMR). The input readings are passed to a 2-D partial response (PR) equalizer, which is either linear or CNN-based. The equalized waveforms are inputs to a 2-D BCJR detector, which generates log-likelihood-ratio (LLR) outputs. The CNN MNP is provided with BCJR LLRs to estimate signal-dependent media noise samples and feed them back to the BCJR. A second pass through the BCJR produces LLRs, which are decoded by an LDPC decoder; achieved areal density (AD) is computed from the LDPC code rate. Spatially varying read- and write-TMR models are developed. We investigate the performance of the proposed system on simulated TDMR readback waveforms generated by grain-switching probabilistic (GSP) simulations. We have two types of GSP datasets. Dataset #1 includes two 10 nm bit length (BL) datasets with 18 and 24 nm track pitch (TP). Dataset #2 has 11 nm BL and 15 nm TP. The comparison baseline is a 1-D BCJR detector with pattern-dependent noise prediction (PDNP) and soft intertrack interference (ITI) subtraction, referred to as 1-D PDNP with LLR exchange. The write-TMR and read-TMR are modeled as cross-track-independent downtrack-correlated random processes. In the presence of joint write- and read-TMR, the proposed turbo-detection system achieves 8.34% and 0.70% AD gain over 1-D PDNP with LLR exchange for TP 18 and 24 nm dataset #1, respectively, and is more robust to TMR compared to the baseline.

Blind Identification of Polar Codes Based on Estimation and Derivation Approaches

The blind identification of polar codes is to identify code parameters such as the code length, the number and positions of information bits in a polar code in non-cooperative communications. In this letter, we propose two low-complexity algorithms to identify code length and information bits of polar codes, respectively, by taking the union of both the estimated code parameters and the derived code parameters from the allowable shortest code without the candidate code sets. Simulations show that our proposed scheme is robust to the error and significantly improves the identification performance as compared to the existing purely code parameter estimation approaches.

Design of Implicit Partial Product-LDPC Codes and Low Complexity Decoding Algorithm

In this letter, we are concerned with a recently proposed class of product codes, called implicit partial product low-density parity-check (IP-LDPC) codes, which consist of LDPC codes for rows and Bose-Chaudhuri-Hocquenghem (BCH) codes for columns. Distinguished from the conventional product codes, only partial columns are doubly-protected and the column checks are transmitted implicitly rather than explicitly. For any given LDPC code, we present three heuristic rules to design an IP-LDPC code with the same code rate, showing how to select the number of doubly-protected columns and the BCH code (for columns). The stringent constraint is that the product of the number of doubly-protected columns and the length of syndrome per column must be less than or equal to the product of the number of the rows and the length of extra bits that can be carried reliably and implicitly per row (LDPC codeword). We also propose a simple bit-flipping algorithm for the column decoding in the case when the number of unsuccessfully decoded rows is relatively small, which occurs often especially when the iterative decoding is implemented. The simulation results show that IP-LDPC codes can lower down the word error rate (WER) of a (3,6)-regular LDPC code with length 1024 from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−6</sup> at the SNR around 2.0 dB but without any code rate loss.

Research of application of low-resource cryptography algorithms in decentralized environments

The purpose of this material is to analysis of the application of low-resource cryptography algorithms for Internet of Things (IoT) systems and the possibility of their implementation in decentralized systems. Over the past few years, the Internet of Things has become one of the most important technologies of the century. Modern IT developments has reached a high level of technological development, which allows you to customize the interaction between IoT devices and provide connection between people. With the appearance of 5G technologies, the IoT has become the center of development, for almost to all modern industries. Devices in this architecture are significantly smaller and have low power consumption. Conventional encryption algorithms tend to be computationally expensive due to their complexity and require many processing rounds. Low-resource cryptography is a compromise between implementation cost, speed, security, performance, and power consumption on IoT devices. The motivation for lightweight cryptography is to use less memory, less computing resources, and less power consumption to provide a security solution that can run on resource-constrained devices. Block ciphers have a fixed length (of bits) and special transformation stages, which are determined by a symmetric key. Block ciphers are quite versatile, which is very useful from an IoT perspective. Another advantage is that block ciphers has nearly proportional encryption and decryption methods. Therefore, it can be implemented with fewer resources.

Dependence of Bit Error Rates on HAMR Transition Curvatures

Transition curvature limits the performance of heat-assisted magnetic recording (HAMR), especially when bit length (BL) is reduced below 10 nm. In this article, in order to quantify this issue, the dependence of signal-to-noise ratios (SNRs) and bit error rates (BERs) on HAMR transition curvatures is investigated utilizing previously obtained curvature values. An artificial recording method is used and a Viterbi algorithm is applied to decode the readback signals and calculate BERs. A pseudorandom binary sequence (PRBS) is used. Two BLs are tested: 7.5 and 8.5 nm. Different reader widths (RWs), shield-to-shield distances, and magnetic fly heights are studied in order to seek optimized reader configurations. Generally, transition curvatures have a negative effect on SNR and BER performance, but this effect can be mitigated by the reduction of certain reader dimensions.

Effect of process parameters on the temperature changes during robotic bone drilling.

In medical surgery, bone drilling is an inevitable procedure. The thermal necrosis in the drilling process can affect post-operative recovery. In this study, the method of drill bit precooling is proposed in bone drilling with robot assisted system. The influence of process parameters on the drilling temperature were investigated and analyzed. The results showed that the method of drill bit precooling could reduce the drilling temperature. The drill bit starting temperature and the feed rate were more important parameters on the drilling temperature compared with rotational speed and cooling length of the drill bit. The quadratic regression model obtained from response surface experiments can predicted the drilling temperature correctly under the range of process parameters in this study. The optimal parameter combination is rotational speed = 1610 rpm, feed rate = 0.5 mm/s, the starting temperature of drill bit = 8°C, and the cooling length = 34.8 mm. The results provide an effective method to reduce thermal necrosis of bone cells in drilling.

Comparative Analysis of Image Enhancement Algorithms

In the complex instruments utilised in essential fields such as satellite cameras, CT scanners, and High-Resolution Cameras (Underwater), image capture is critical without human-rated aberrations, sounds, or atmospheric disturbances. Even full reference QA (quality assessment) approaches have a limited ability to predict quality accurately. As a result, the difficulty of evaluating and enhancing photographs is further subdivided into domain-specific issues by focusing on a small set of artefacts. The most popular is entropy, which is usually relevant in picture coding: it is a lower limit for the average coding length in bits per pixel that may be attained without any loss of information by an optimal coding scheme. The word 'specific' is significant because it establishes right away that the strategies covered in this paper are primarily problemsolving techniques. For example, a procedure that works well for improving X-ray images may not be the ideal option. Thus, a method that works well for boosting X-ray photos may not be the greatest option for enhancing photographs obtained by a satellite thousands of miles away from the Earth. Image enhancement algorithms proposed in this paper are Intensity-Hue-Saturation transformation, Histogram Equalization algorithms, Edge Detection techniques and Retinex theory algorithms. These algorithms are implemented under satellite imagery, medical scans, underwater images, and their parameter analysis.

DCGAN-based symmetric encryption end-to-end communication systems

In this article, we propose a symmetric encryption end-to-end communication system based on deep convolutional generative adversarial networks to solve the security problem of transmission in end-to-end learning-based wireless communication systems. The system generates a key by a deep convolutional generative adversarial network and shares it to the transmitter and receiver. Both the transmitter and receiver are represented by convolutional neural networks. We propose to use neural networks as a bridge to make an irreversible mapping relationship between the message and the key. The proposed method achieves more secure message transmission than the symmetric encryption end-to-end communication systems using randomly generated keys. We also propose a concept of the error impact factor to explain the system’s characteristics. From the simulation results, the proposed method can achieve encryption transmission of arbitrary length bit messages. The system has excellent performance on additive white Gaussian noise channels and Rayleigh fading channels. The legitimate parties can establish secure transmission in this setting, and the illegal eavesdropper cannot decode accurately without the key.

Implementasi Algoritma SHA-256 Pada Aplikasi Duplicate Document Scanner

On a computer, if we duplicate a file, the duplicated file is no different from the first file and this can be done in a fairly short time. In this case, what will be duplicated is a word document file with docx extension. SHA (Secure hash Algorithm) is a hash algorithm that is relatively new. The selection of the SHA-256 algorithm is inseparable from several previous studies that have examined the performance of this algorithm. The SHA-256 algorithm is able to detect changes that occur in digital images even though the changes that occur are only 1 pixel, the small differences that occur in the image produce a very significant difference from the hash value with an accuracy level of up to 100%. SHA - 256 produces a message digest with 256 bits in length. SHA - 256 is classified as safe because it is designed in such a way that it is not possible to get messages related to the same message digest.

Constructing New Representative Collective Signature Using the GOST R34.10-2012

A representative collective signature is a signature created by a collective of multiple signing groups. The basic requirement for this signature is that it must include information about all participants involved in the signing process of a given document. The U component in the 3-component collective signature (including U, E, S) is used to satisfy this requirement. In this paper, we propose a new form of representative collective signature consisting of only two components (e, s), then, the information of all signers is contained in the pseudo-random parameter R. The purpose of this is both to reduce the size of the signature, as well as ensure that the manager of the signing group has enough information to identify the signer and to prevent "disclaimer" during a dispute. In the proposed collective signature scheme, we use the GOST R34.10-2012 digital signature standard to develop a consensus group signature scheme based on the discrete logarithm problem on the Elliptic curve. This scheme allows the generation of a representative collective signature: i) Only 512 bits in length, but still achieves security level 2512 and ii) Significantly reduced computational performance (in comparison to the representative collective signature that represents the three components).

Study on the development of a machine to prepare the soil for cotton sowing on ridges

The aim of this paper is to create a combined machine for planning the soil for sowing cotton on the edges. A total for the execution of the innovation of planning the soil for sowing cotton on the edges was developed, which comprises of a dump deep-dredger with a slanted rack and a comb-maker. The essential standards and strategies of classical mechanics, numerical examination and measurements were utilized in this paper. The plan conspire of the combined unit is advocated. The following results were obtained from the outcomes of multivariate tests set up: the width of the ripper within the extend of 10.5-11.03 cm, the disintegrating point of 27°, the point of establishment of the plowshare edge to the heading of movement of 31°. The arrangement of edges of the desired degree with negligible vitality utilization is given with a width and length of the deep-dredger bit, separately, of 5 and 20 cm, edge hold width of 21 cm, the length of its wing within the run of 47-49 cm, and a least longitudinal.

Fast Implementation of the Rivest-Shamir-Adleman (RSA) Algorithm with Robust Packet Data Loss Detection Function

Encryption is the process of protecting information from unauthorized parties by converting such information into an unreadable form. Packet data is a method of transferring data, broken into bits called packets which travels over a network. Packet losses occur when packets fail to reach their destination devices as a result of network congestion, faulty routers or as a result of an attack. Encryption is the standard method for making a communication private. In sending a private message to another user, it is first encrypted (termed encipher), the intended recipient alone knows how to correctly decrypt (decipher) the message. There are several algorithms developed for the purpose of encryption which provides data security and integrity. This paper proposes the use of the Rivest-Shamir-Adleman (RSA) algorithm to implement a system for encrypting text files of any length (by breaking long messages into valid blocks and encrypting each block) capable of being transmitted using a Simple Mail Transfer Protocol (SMTP). Probable primes, 3048 bits in length are generated to be used in the generation of public, private key pairs for encryption and decryption. The proposed scheme is better because the route taken during transmission of data is recorded and packet losses are also checked for during transmission of encrypted files as compared to known state-of-the-art schemes.

Joint-Mapping Orthogonal Frequency Division Multiplexing With Subcarrier Number Modulation

Orthogonal frequency division multiplexing with subcarrier number modulation (OFDM-SNM) has been recently proposed to improve the spectral efficiency (SE) of the traditional OFDM system. In this paper, we propose a joint-mapping OFDM-SNM (JM-OFDM-SNM) scheme to transmit the signal vector with a constant length of information bits by jointly considering the subcarrier activation patterns and constellation symbols. A low-complexity detection scheme based on log-likelihood ratio criterion is proposed to relieve the high computational complexity of the maximum-likelihood detection at the cost of a negligible performance loss. Upper-bounded bit error rate (BER) and lower-bounded achievable rate are both derived in closed-form to evaluate the performance of JM-OFDM-SNM. To suit different application scenarios, we further propose two enhanced schemes, named adaptive JM-OFDM-SNM (AJM-OFDM-SNM) and JM-OFDM with in-phase/quadrature SNM (JM-OFDM-IQ-SNM), where the former adjusts the constellation orders for different numbers of active subcarriers, and the latter extends the indexing to in-phase and quadrature domains. Simulation results corroborate the tightness of the derived BER expression in the high signal-to-noise ratio region and show that (A)JM-OFDM-SNM improves the performance of OFDM-SNM, while both AJM-OFDM-SNM and JM-OFDM-IQ-SNM schemes perform better than JM-OFDM-SNM at the same SE.

Dependence of HAMR Transition Curvature on Bit Length

Transition curvature is a major contributor to transition broadening in current heat-assisted magnetic recording (HAMR) devices. In this article, in order to clarify HAMR performance versus bit length (BL), a detailed study of the dependence of HAMR transition curvature on BL is presented. With the help of micromagnetic simulations, HAMR bits with three different BLs (10.5, 15, and 21 nm) are written and transition curvatures are calculated. Both thermal exchange coupling composite (ECC) media and pure FePt media are tested. By tracking the change of transition curvature during the HAMR cooling process, an erase-after-write effect is observed. DC-erased media, introduction of intergranular exchange, and removal of dipole interactions are also examined for potential optimization of the HAMR system.

Asynchronous Chirp Slope Keying for Underwater Acoustic Communication

We propose an asynchronous acoustic chirp slope keying to map short bit sequences on single or multiple bands without preamble or error correction coding on the physical layer. We introduce a symbol detection scheme in the demodulator that uses the superposed matched filter results of up and down chirp references to estimate the symbol timing, which removes the requirement of a preamble for symbol synchronization. Details of the implementation are disclosed and discussed, and the performance is verified in a pool measurement on laboratory scale, as well as the simulation for a channel containing Rayleigh fading and Additive White Gaussian Noise. For time-bandwidth products (TB) of 50 in single band mode, a raw data rate of 100 bit/s is simulated to achieve bit error rates (BER) below 0.001 for signal-to-noise ratios above −6 dB. In dual-band mode, for TB of 25 and a data rate of 200 bit/s, the same bit error level was achieved for signal-to-noise ratios above 0 dB. The simulated packet error rates (PER) follow the general behavior of the BER, but with a higher error probability, which increases with the length of bits in each packet.