Showing papers on "Hadamard code published in 2020"
TL;DR: It is established that some Z 2 s -linear Hadamard codes of length 2 t are equivalent, once t is fixed, which allows us to improve the known upper bounds for the number of such nonequivalent codes.
15 citations
TL;DR: A new numerical mapping method based on Walsh codes is proposed to detect the coding regions in eukaryotes and is efficient as it attains 94 % accuracy, 85 % sensitivity and 96 % specificity when tested on the benchmark C. Elegans gene sequence.
15 citations
TL;DR: A multi-user cross-layer security network implemented on the optical code-division multiple access (OCDMA) with newly designed hybrid 2D-modified Walsh code (MWC) along with an algorithmic approach in cryptography domain is presented.
Abstract: We present the development of a multi-user cross-layer security network implemented on the optical code-division multiple access (OCDMA) with newly designed hybrid 2D-modified Walsh code (MWC) along with an algorithmic approach in cryptography domain. Minimum BER value is evaluated on the order of 10 − 50 using our designed MWC, which is comparatively lower than other existing codes. The security performance of the network was analyzed using the probability detection parameter, which was found to be superior apart from few other available existing codes. The enhancement of the quality and grade of security in this network eavesdropper can intercept the designed optical code of OCDMA in the physical layer. It compels one to break the security in the data-layer to access the original code. We also calculated the probability of successful data interception as a function of time complexity. Furthermore, we presented the simulation of the hybrid system using the OptiSystem simulator.
6 citations
TL;DR: Using multiple antennas at the transmitter end, this system can inhibit the channel fading problem and then obtain more diversity gain and theoretical analysis is consistent with simulation results and shows that the new system outperforms other DCSK-based systems.
Abstract: In this paper, a novel non-coherent communication system, multi-user orthogonal high efficiency differential chaos shift keying (MU-OHE-DCSK) system is presented. In the proposed system, by using an orthogonal chaotic generator (OCG) to generate two orthogonal chaotic signals, therefore the intra-signal interference components in MU-OHE-DCSK are eliminated. As in high efficiency differential chaos shift keying (HE-DCSK), the reference signal is transmitted in the first time slot. The 2 N data bits are spread by chaotic sequence and then separated through Walsh codes in the second time slot of the frame. As a result, the superiority of this proposed system is that it can enhance the spectral efficiency when compared with DCSK and HE-DCSK. Furthermore, using multiple antennas at the transmitter end, this system can inhibit the channel fading problem and then obtain more diversity gain. The BER formula of multiple-input single-output MU-OHE-DCSK (MISO-MU-OHE-DCSK) is derived under the assumption of the proposed system over Rayleigh fading channels, respectively. Theoretical analysis is consistent with simulation results and shows that the new system outperforms other DCSK-based systems.
6 citations
08 Oct 2020
TL;DR: The proposed scheme is combined with a carrier recovery method for MWHCDM to improve acquisition performance and employs a novel evaluation function, which remarkably improves the initial acquisition performance.
Abstract: Walsh-Hadamard code division multiplexing (WHCDM) is suitable for helicopter satellite communications as it has robustness against a periodic channel blockage due to rotor blades. Modified WHCDM (MWHCDM) enhances robustness and achieves excellent bit error rate performance. However, the initial acquisition performance of MWHCDM is inferior to that of WHCDM, which has less robustness. To solve this problem, we propose a novel initial acquisition scheme for MWHCDM in this paper. The proposed scheme is combined with a carrier recovery method for MWHCDM to improve acquisition performance. Additionally, it employs a novel evaluation function. The computer simulation confirms the proposed scheme remarkably improves the initial acquisition performance.
1 citations
TL;DR: The proposed non-coherent chaos-based communication that combined Orthogonal Multilevel Code-Shifted Differential Chaos Shift Keying with orthogonal frequency division multiplexing named (OFDM-OMCS-DCSK) modulation system has the best BER performance with high data rate feature.
Abstract: In this paper, a new non-coherent chaos-based communication that combined orthogonal multilevel code-shifted differential chaos shift keying with orthogonal frequency division multiplexing named (OFDM-OMCS-DCSK) modulation system. New orthogonal chaotic signal sets are generated by hybrid gram-schmidt algorithm and walsh code function and used it to carry high data rate in the same time slot. The bandwidth efficiency of the OFDM-OMCS-DCSK system is comparing with conventional system. Also, the BER analytic expressions are derived under (AWGN) and multipath Rayleigh fading channels and comparing with the simulation results. Furthermore, the BER performance is compared with OFDM-DCSK to found that the proposed system has the best BER performance with high data rate feature.
1 citations
08 Oct 2020
TL;DR: Results of computer simulation show that MWHCDM gets more robust to carrier frequency offset with the proposed scheme, which makes it possible to update the frequency error signal twice per symbol.
Abstract: Walsh-Hadamard code division multiplexing (WHCDM) is attractive to helicopter satellite communications due to its capability to overcome periodic channel blockage with rotor blades. Modified WHCDM (MWHCDM) is more attractive in terms of spectral efficiency. However, MWHCDM is relatively less robust to carrier frequency offset than WHCDM. This paper addresses automatic frequency control (AFC) for MWHCDM. We pay attention to the structure of the MWHCDM signal and propose an improved AFC scheme. The proposed scheme makes it possible to update the frequency error signal twice per symbol. Results of computer simulation show that MWHCDM gets more robust to carrier frequency offset with the proposed scheme.
1 citations
Patent•
25 Feb 2020
TL;DR: In this article, a differential chaotic communication method and system based on polarization codes was proposed, which comprises a coding modulation process and a demodulation decoding process, where the decoding result is obtained according to the information transmission rate and performance of communication.
Abstract: The invention relates to a differential chaotic communication method and system based on polarization codes The method comprises a coding modulation process and a demodulation decoding process The code modulation process comprises the following steps: after a signal source generates a signal, inputting the signal into a polarization code encoder for encoding, then sending a code word encoded bya polarization code into a DDCSK-WC modulator for chaotic modulation, redesigning a data frame by utilizing an orthogonal Walsh code, and sending the redesigned data frame; wherein the demodulation and decoding process comprises the steps that after a receiving end receives a signal, a DDCSK-WC demodulator demodulates the received signal, soft information obtained through demodulation is input into a polarization code decoder, the polarization code decoder decodes the soft information through an SC decoding algorithm based on an MS algorithm, and finally a decoding result is obtained According to the method and the system, the information transmission rate and performance of communication are improved, and the calculation complexity and the implementation cost are reduced
08 Oct 2020
TL;DR: In this article, a 2D-Hadamard Code based on convolutional neural network (CNN) was proposed to overcome the theoretical limit of (d − 1)/2 bits, where d is a minimum Hamming distance.
Abstract: Error Correcting Codes play an essential role in the digital communication. Especially a new digital technology like video watermarking demands sufficient error correcting capabilities, because of very high compression ratio (about 1:200). Normally the watermarks can barely survive such massive attacks, despite very sophisticated embedding strategies. In this paper, the authors introduce a new approach for Error Correcting Code based on 2D Hadamard Code and convolutional Neuronal Network (CNN). The main idea is that the 2D-Hadamard code words can be represented as 2D basis images. The errors cause a noise in these basis images. The decoding procedure of this 2D-Codewords is realized by a CNN, which was before trained with these basis images. With this approach, it is possible to overcome the theoretical limit of error correcting capability of (d − 1)/2 bits, where d is a minimum Hamming distance. To prove the efficiency and practicability of this new 2D Hadamard Code, the method was applied to a video Watermarking Coding Scheme. The Video Watermarking Embedding procedure decomposes the initial video through Multi-Level Interframe Wavelet Transform. The low pass filtered part of the video stream is used for embedding the watermarks, which are protected respectively by CNN based 2D Hadamard Code.
Patent•
02 Jun 2020
TL;DR: In this article, a geodetic system identification electromagnetic exploration method based on multipath orthogonal coding is described. But the method is not suitable for the use of the geodesic data.
Abstract: The invention discloses a geodetic system identification electromagnetic exploration method and a geodetic system identification electromagnetic exploration system based on multipath orthogonal coding. The geodetic system identification electromagnetic exploration method comprises the following steps of: sampling an input signal to obtain a discrete signal; carrying out discrete Walsh transform onN discrete data to obtain coefficients of N Walsh codes; selecting N mutually orthogonal Walsh functions from a Walsh code orthogonal set, and multiplying the Walsh functions by coefficients of the NWalsh codes in a one-to-one correspondence manner to obtain N paths of spread spectrum orthogonal coded signals; combining the N paths of orthogonal coded signals to obtain a total transmitting signal and transmitting the total transmitting signal to a geodetic system; and receiving a total signal transmitted by the geodetic system, performing separation on the total signal by utilizing the N Walsh functions to obtain N paths of receiving signals, and calculating impulse response and noise of the geodetic system by utilizing the N paths of receiving signals. According to the geodetic system identification electromagnetic exploration method and the geodetic system identification electromagnetic exploration system, multipath spread spectrum is carried out on the original input signal, so that the solving precision of the impulse response of the earth system is improved, useful signals and noise are effectively separated, and a basis is provided for acquiring earth medium parameters withhigher accuracy.
01 Nov 2020-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: A new fast readout circuit employing the known coding scheme of code division multiple access (CDMA), known originally as a coding scheme for data communication, is successfully designed and applied to a 7-inch ultra-thin, flexible on-cell touch screen panel (TSP).
Abstract: A new fast readout circuit employing the known coding scheme of code division multiple access (CDMA) is successfully designed and applied to a 7-inch ultra-thin, flexible on-cell touch screen panel (TSP). The adopted CDMA is known originally as a coding scheme for data communication, which is applied in this study to address the sensing electrodes of the ultra-thin flexible touch panel. Due to the orthogonality between the driving signals to the touch panel coded by Walsh transform, one type of CDMA, the interference noises between sensing electrodes can be reduced effectively to render accurate touch sensing results. The electromagnetic interference from the flexible display can also be filtered out as baseline component in the output signal. And the frame time of touch reporting can be substantially shortened. Following the sensing electrode is a new readout designed of the switched-capacitor (SC) circuit, to avoid distributing sample signals from parasitic capacitance and also to enlarge the voltage changes due to the capacitance changes caused by touches. A 12-bit analog-to-digital converter (ADC) is orchestrated after the SC circuit to transform the front-end analog signal to digital codes. The digital part of the designed readout adopts a correction algorithm to eliminate the background signals from the display, and also a moving average algorithm to minimize the higher-frequency noises from the display and other electrodes. Experiments are conducted to validate the expected performance. It is evidenced that the Walsh code driving algorithm improves the quality of the readout output signal to be in 42 dB SNR, the report rate to a fast 240 Hz, and a power consumption of 0.39 mW by each sensing channel.