scholarly journals Time-Domain Blind ICI Compensation in Coherent Optical FBMC/OQAM System

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6397
Author(s):  
Binqi Wu ◽  
Jin Lu ◽  
Mingyi Gao ◽  
Hongliang Ren ◽  
Zichun Le ◽  
...  
Keyword(s):  
Phase Noise ◽  
Discrete Cosine Transform ◽  
Time Domain ◽  
Phase Error ◽  
Transmission System ◽  
Cosine Transform ◽  
Noise Compensation ◽  
Decision Error ◽  
Dct Coefficients ◽  
The Time Domain

A blind discrete-cosine-transform-based phase noise compensation (BD-PNC) is proposed to compensate the inter-carrier-interference (ICI) in the coherent optical offset-quadrature amplitude modulation (OQAM)-based filter-bank multicarrier (CO-FBMC/OQAM) transmission system. Since the phase noise sample can be approximated by an expansion of the discrete cosine transform (DCT) in the time-domain, a time-domain compensation model is built for the transmission system. According to the model, phase noise compensation (PNC) depends only on its DCT coefficients. The common phase error (CPE) compensation is firstly performed for the received signal. After that, a pre-decision is made on a part of compensated signals with low decision error probability, and the pre-decision results are used as the estimated values of transmitted signals to calculate the DCT coefficients. Such a partial pre-decision process reduces not only decision error but also the complexity of the BD-PNC method while keeping almost the same performance as in the case of the pre-decision of all compensated signals. Numerical simulations are performed to evaluate the performance of the proposed scheme for a 30 GBaud CO-FBMC/OQAM system. The simulation results show that its bit error rate (BER) performance is improved by more than one order of magnitude through the mitigation of the ICI in comparison with the traditional blind PNC scheme only aiming for CPE compensation.

scholarly journals Phase Tracking Sequences for 5G NR in 52.6-71 GHz Band: Design and Analysis

2021 ◽  
Author(s):  
Alexander Maltsev ◽  
Andrey Pudeev ◽  
Seonwook Kim ◽  
Suckchel Yang ◽  
Seunghwan Choi ◽  
...  
Keyword(s):  
Phase Noise ◽  
Time Domain ◽  
Communication Systems ◽  
Phase Error ◽  
Reference Signal ◽  
Phase Tracking ◽  
Noise Compensation ◽  
Novel Approach ◽  
Filter Size ◽  
Training Resources

This paper presents a novel approach to the phase tracking reference signal (PTRS) design for phase noise impact compensation in the 5G NR communication systems intended to work in a new 52.6 GHz to 71 GHz frequency band. For detailed problem illustration, the phase noise compensation algorithms are discussed and explained, from the basic common phase error (CPE) compensation to the MMSE-base inter-carrier interference (ICI) filtering. Performance of the different phase noise compensation algorithms is investigated for the baseline PTRS accepted in the current 5G NR specification and compared with the newly proposed approach to the PTRS design. This approach is based on nulling the subcarriers adjacent to the reference signals to minimize influence of the ICI on the estimation process. It was shown that new nulling PTRS design outperforms currently used distributed PTRS structure. In addition, numerical results represent a trade-off between the filter size and the amount of the allocated training resources to achieve better performance. It was shown that proposed PTRS structures and processing algorithms give ICI compensation level very close to optimal scheme and thus, different approaches (such as time domain compensation) may be required for further progress.

scholarly journals Frequency and Vibration Characteristics of High-Speed Gear-Rotor-Bearing System with Tooth Root Crack considering Compound Dynamic Backlash

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Jie Liu ◽  
Weiqiang Zhao ◽  
Weiwei Liu
Keyword(s):  
Time Domain ◽  
Crack Depth ◽  
Transmission System ◽  
Gear System ◽  
Time Varying ◽  
Tooth Root ◽  
Meshing Stiffness ◽  
The Time Domain ◽  
Center Distance ◽  
Root Crack

Considering the microstructure of tooth surface and the dynamic characteristics of the vibration responses, a compound dynamic backlash model is employed for the gear transmission system. Based on the fractal theory and dynamic center distance, respectively, the dynamic backlash is presented, and the potential energy method is applied to compute the time-varying meshing stiffness, including the healthy gear system and the crack fault gear system. Then, a 16-DOF coupled lateral-torsional gear-rotor-bearing transmission system with the crack fault is established. The fault characteristics in the time-domain waveform and frequency response and statistics data are described. The effect of crack on the time-varying meshing stiffness is analyzed. The vibration response of three backlash models is compared. The dynamic response of the system is explored with the increase in crack depth in detail. The results show that the fault features of countershaft are more obvious. Obvious fluctuations are presented in the time-domain waveform, and sidebands can be found in the frequency domain responses when the tooth root crack appears. The effect of compound dynamic backlash on the system is more obvious than fixed backlash and backlash with changing center distance. The vibration displacement along meshing direction and dynamic meshing force increases with the increase in crack depth. Backlash and variation of center distance show different tendencies with increasing crack depth under different rotational speeds. Amplitude of the sidebands increases with crack depth increasing. The amplitude of multiplication frequency of rotational frequency has an obvious variation with growing crack depth. The sidebands of the multiplication frequency of meshing frequency show more details on the system with complex backlash and crack fault.

A Novel Hybrid Discrete Cosine Transform Speeded Up Robust Feature-Based Secure Medical Image Watermarking Algorithm

2020 ◽  
Vol 10 (11) ◽  
pp. 2588-2599
Author(s):  
Saqib Ali Nawaz ◽  
Jingbing Li ◽  
Uzair Aslam Bhatti ◽  
Anum Mehmood ◽  
Raza Ahmed ◽  
...  
Keyword(s):  
Discrete Cosine Transform ◽  
Digital Watermarking ◽  
Copyright Protection ◽  
Image Watermarking ◽  
Image Feature ◽  
Feature Descriptor ◽  
Cosine Transform ◽  
Speeded Up Robust Features ◽  
Feature Based ◽  
Dct Coefficients

With the advancement of networks and multimedia, digital watermarking technology has received worldwide attention as an effective method of copyright protection. Improving the anti-geometric attack ability of digital watermarking algorithms using image feature-based algorithms have received extensive attention. This paper proposes a novel robust watermarking algorithm based on SURF-DCT perceptual hashing (Speeded Up Robust Features and Discrete Cosine Transform), namely blind watermarking. We design and implement a meaningful binary watermark embedding and extraction algorithm based on the SURF feature descriptor and discrete-cosine transform domain digital image watermarking algorithm. The algorithm firstly uses the affine transformation with a feature matrix and chaotic encryption technology to preprocess the watermark image, enhance the confidentiality of the watermark, and perform block and DCT coefficients extraction on the carrier image, and then uses the positive and negative quantization rules to modify the DCT coefficients. The embedding of the watermark is completed, and the blind extraction of the watermark realized. Correlation values are more than 90% in most of the attacks. It provides better results against different noise attacks and also better performance against rotation. Transparency and high computational efficiency, coupled with dual functions of copyright protection and content authentication, is the advantage of the proposed algorithm.

scholarly journals Efficient Image Cipher Based on Baker Map in the Discrete Cosine Transform

2020 ◽  
Vol 20 (1) ◽  
pp. 68-81
Author(s):  
Hesham Alhumyani
Keyword(s):  
Discrete Cosine Transform ◽  
Experimental Tests ◽  
Differential Sensitivity ◽  
Cosine Transform ◽  
Chaotic Baker Map ◽  
Image Cipher ◽  
Plain Image ◽  
Dct Coefficients ◽  
Inverse Dct ◽  
Baker Map

AbstractThis paper presents an efficient image cipher based on applying the chaotic Baker Map (BM) in the Discrete Cosine Transform (DCT). The encryption module of the proposed DCT-based BM image cipher employs a DCT on the original plain-image then, the DCT coefficients of the plain-image are shuffled with the BM. Finally, the inverse DCT is applied to the shuffled plain-image DCT coefficients to obtain the final cipher-image. The decryption module of the proposed DCT-based BM image cipher employs a DCT on the input cipher-image then, the DCT coefficients of the cipher-image are inversely shuffled with the BM. Finally, the inverse DCT is applied to the inversely shuffled cipher-image DCT coefficients to obtain the original plain-image. A set of experimental tests are performed to test the validity of the proposed DCT-based BM image cipher and the performed tests demonstrated the superiority of the proposed DCT-based BM image cipher in terms of statistical, differential, sensitivity and noise immunity.

Face Recognition System using Discrete Cosine Transform combined with MLP and RBF Neural Networks

2012 ◽  
Vol 4 (4) ◽  
pp. 11-35 ◽  
Author(s):  
Fatma Zohra Chelali ◽  
Amar Djeradi
Keyword(s):  
Neural Networks ◽  
Face Recognition ◽  
Discrete Cosine Transform ◽  
Recognition Rate ◽  
Recognition System ◽  
Rbf Neural Networks ◽  
Cosine Transform ◽  
Linear Discriminant ◽  
Face Recognition System ◽  
Dct Coefficients

Proposed is an efficient face recognition algorithm using the discrete cosine transform DCT Technique for reducing dimensionality and image parameterization. These DCT coefficients are examined by a MLP (Multi-Layer Perceptron) and radial basis function RBF neural networks. Their purpose is to present a face recognition system that is a combination of discrete cosine transform (DCT) algorithm with a MLP and RBF neural networks. Neural networks have been widely applied in pattern recognition for the reason that neural-networks-based classifiers can incorporate both statistical and structural information and achieve better performance than the simple minimum distance classifiers. The authors demonstrate experimentally that when DCT coefficients are fed into a back propagation neural network for classification, a high recognition rate can be achieved by using a very small proportion of transform coefficients. Comparison with other statistical methods like Principal component Analysis (PCA) and Linear Discriminant Analysis (LDA) is presented. Their face recognition system is tested on the computer vision science research projects and the ORL database.

Decision-directed phase noise compensation for millimeter-wave single carrier systems with iterative frequency-domain equalization

2010 ◽  
Vol 2 (3-4) ◽  
pp. 399-408 ◽  
Author(s):  
Satoshi Suyama ◽  
Junichi Onodera ◽  
Hiroshi Suzuki ◽  
Kazuhiko Fukawa
Keyword(s):  
Phase Noise ◽  
Frequency Domain ◽  
Millimeter Wave ◽  
Time Domain ◽  
Wave Band ◽  
60 Ghz ◽  
Transmission Performance ◽  
Frequency Domain Equalization ◽  
Noise Compensation ◽  
Single Carrier

This paper proposes a receiver that repeats iterative frequency-domain equalization (FDE) and decision-directed phase noise compensation (DD-PNC) to alleviate degradation due to the phase noise for millimeter-wave single carrier (SC) systems. High bit-rate SC-FDE transceivers based on the single-chip Si RF-CMOS IC technology in the 60-GHz millimeter-wave band have been extensively studied for wireless personal area network (WPAN) systems, and the relatively large phase noise in a phase-locked loop (PLL) synthesizer severely degrades transmission performance. In an initial processing of the proposed receiver, a cyclic prefix (CP)-based phase noise compensator (CP-PNC) removes the phase noise from a time-domain received signal by using CP, which is known to the receiver, and the channel is equalized by the iterative FDE using the conventional minimum mean-square-error (MMSE) weight. In an iterative processing, DD-PNC estimates the phase noise each symbol by exploiting an output of a channel decoder, and then compensates the time-domain received signal for the phase noise by using the estimate. In order to equalize the compensated received signal, the iterative FDE performs both the MMSE filtering and residual inter-symbol interference cancelation using the decoder output. Computer simulations following the 60-GHz WPAN standard demonstrate that in the 64QAM with the coding rate of 3/4, the proposed receiver with three iterations can drastically remove the phase noise of −85 dBc/Hz at 1 MHz offset, and that it can achieve excellent transmission performance.

A VLSI Implementation of Filterbank for MPEG2/4 AAC Encoder

2011 ◽  
Vol 378-379 ◽  
pp. 569-572
Author(s):  
Tsung Han Tsai ◽  
Yu Jie Sha
Keyword(s):  
Frequency Domain ◽  
Discrete Cosine Transform ◽  
Time Domain ◽  
Vlsi Architecture ◽  
Low Complexity ◽  
Hardware Cost ◽  
Audio Quality ◽  
Input Signals ◽  
Audio Files ◽  
The Time Domain

In this paper, we proposed a VLSI architecture of the modified discrete cosine transform (MDCT) for MPEG 2/4 AAC encoders. The MDCT transforms the time domain input signals to the frequency domain spectrums. It is considered one of the most computational intensive part in implementing the AAC encoder. The AAC encoder allows four types of audio blocks while encoding the audio files. With our algorithm, the proposed design can share the coefficients needed in the MDCT. Moreover, we used a 2-dimensional folding technique to reduce the hardware cost while maintaining the audio quality. The proposed design is realized in TSMC 0.18-um 1P6M technology and is operated at 50 MHz. With these techniques on special hardware design, the result shows some advantages on low complexity.

scholarly journals Keamanan Pesan Rahasia Menggunakan Steganografi DCT (Discrete Cosine Transform) pada Citra JPEG

2019 ◽  
Vol 9 (2) ◽  
Author(s):  
Dian Hafidh Zulfikar
Keyword(s):  
Discrete Cosine Transform ◽  
Spatial Domain ◽  
Cover Image ◽  
Secret Message ◽  
Least Significant Bit ◽  
Cosine Transform ◽  
Secret Information ◽  
Dct Coefficients ◽  
Lsb Technique ◽  
Dct Coefficient

<p class="SammaryHeader" align="center"><strong><em>Abstract</em></strong><em></em></p><p><em> </em>The  least significant-bit (LSB) based techniques are very popular for steganography in spatial domain. The simplest LSB technique simply replaces the LSB in the cover image with the  bits from secret information. Further advanced techniques use some criteria to identify the pixels in which LSB(s) can be replaced with the bits of secret information. In Discrete Cosine Transform (DCT) based technique insertion of secret information in carrier depends on the DCT coefficients. Any DCT coefficient value above proper threshold is a potential place for insertion of secret information.</p><p class="Abstrak"><strong> </strong><strong>Keywords :</strong> Discrete Cosine Transform (DCT), steganography, secret message</p><p><strong><em> </em><em>Abstra</em><em>k</em></strong></p><p>Pada steganografi domain spasial, teknik least significant-bit (LSB) merupakan teknik yang paling banyak digunakan pada steganografi. Teknik yang sederhana yang hanya mengubah nilai LSB pada cover image dengan nilai bit pesan rahasia, atau dengan teknik yang lebih baik lagi yaitu dengan menentukan bit-bit LSB mana yang akan dilakukan pergantian nilai bit. Lain halnya dengan metode Discrete Cosine Transform (DCT), teknik steganografi ini akan menyembunyikan informasi rahasia tergantung dari nilai Koefisien DCT.</p><p class="Abstrak"> </p><p class="Abstrak"><strong>Kata Kunci :</strong> Steganografi, DCT, Citra, JPEG, Pesan Rahasia</p>

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