Spread Spectrum Method Research Articles

Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System

This paper provides a comparative study on radiation noise reduction methods for inductive power transfer systems using spread spectrum. In the spread spectrum methods, the radiation noise is reduced by continuously changing an output frequency of the inverter according to pseudorandom numbers. The effects of the radiation noise reduction are evaluated with the inductive power transfer (IPT) system with series-parallel compensation and series-series compensation. The results show that the peak values of the radiation noise around the fundamental frequency are reduced by 7.8 and 8.1 dBμA in maximum with the series-series compensation method and the series-parallel compensation method, respectively in comparison with the constant frequency operation. From these results, the proposed methods are effective for both the series-series compensation and series-parallel compensation method. Moreover, the efficiency of the IPT system with spread spectrum method is evaluated. The maximum DC-to-DC efficiency with the spread spectrum is 94.1% and 92.0% with the series-series compensation and the series-parallel compensation, respectively.

SINR Model with Enhanced Direct Sequence Spread Spectrum (EDSSS) Method in LTE-Wi-Fi Integrated Networks

Wireless Fidelity (Wi-Fi) has been introduced in Third Group Partnership Project (3GPP) Release 12 as an alternative solution for offloading high traffic in LTE network. In addition, Wi-Fi has many advantages such as low operation cost, easy-installed systems and it is currently widely implemented in houses and offices. However, a phenomenon called co-channel interference may occur within LTE-Wi-Fi networks because of its low power transmission when compared to the macrocell. Hence, Wi-Fi users may suffer worst network degradation at frequency 2.4GHz due to its collision with LTE band 40. In order to solve this network issue, an interference management is needed as it affects users perceive experiences and services when using LTE-Wi-Fi integrated networks. In this paper, a method known as Pulse-Shaping Algorithm (PSA) has been integrated with Direct Sequence Spread Spectrum (DSSS) which is called Enhanced Direct Sequence Spread Spectrum (EDSSS) to model Signal-to-Interference-Noise Ratio (SINR). The introduction of this method is for reducing the occurrence of co-channel interference. Furthermore, a new coefficient named as a radius fraction (β) has been introduced in order to evaluate the SINR expression for User Equipments (UEs) in LTE-Wi-Fi networks. The simulation results discovered that β-coefficient with value of 0.2 has given the most optimum improvement of SINR for LTE and Wi-Fi users. By modifying the SINR expression with PSA method, the network performances for users have improved significantly.

HVS-based scalable video watermarking

Scalable coding methods are widely considered as promising coding approaches for image/video transmission in heterogeneous environments. To copyright protection of scalable coded videos, scalable video watermarking was introduced which enables reconstructing various scales of watermark from watermarked videos. This paper proposes a novel human vision system-based, spread spectrum method to scalable video watermarking. The host video is decomposed using newly proposed spatio-temporal motion-compensated 3D wavelet decomposition, called k( $$\hbox {t}+2\hbox {D}$$ ) DWT decomposition, to frequency sub-bands. A scalable decomposition of the watermark is inserted into the entire frequency sub-bands of decomposed video. At each frequency sub-band, the watermark data are inserted into the selected coefficients of the sub-band frames in a way that the watermark embedding visual artifact occurs in the highly textured, highly contrasted, and very dark/bright areas of the video frames. The experimental results show that the watermarked test videos are highly transparent and robust against scalable video coding even at very low decoding bit-rates and some other video processing attacks. The proposed approach can guarantee copyright protection for scalable coded videos, especially over heterogeneous networks.

Hidden Data Embedding Method Based on the Image Projections Onto the Eigenvectors of Subinterval Matrices

We consider the new method of hidden data embedding based on the transform of the container-image using the apparatus of subinterval matrices of the cosine transform. The developed method deals with the analysis of the container-image projections onto the eigenvectors of subinterval matrices. A decisive rule for the choice of informative and non-informative image projections subsets based on a given significance level is proposed. The computational experiments results of projections partitioning into informative and non-informative subsets show that it is possible to obtain a different numbers of informative and non-informative projections subsets using different significance levels. It allows to implement a hidden embedding of different data amounts. The embedding data are represented by a binary sequence. In our method we proposed to implement the data embedding on the basis of a relative change of given projections values. To test the workability of the developed method computational experiments were carried out. Their results showed that the developed method allows to perform data recovery without distortion, and causes a slight distortions of the image containing the embedded data. Also we carried out comparative computational experiments to compare the results of the developed method application with the results of Е. Koch and J. Zhao method and spread spectrum method. Their results showed that the developed method causes less distortions of the container-image than other ones.

Study on the structure of an efficient receiver for multi-sensors using direct sequence spread spectrum

In underwater acoustic communication, there has been a lot of interest in detection and acquisition of information about multiple sensors as well as detection of information on a single sensor. However, research on multiple sensors access is lacking. In order to acquire information from each sensor in multiple sensors access underwater communication, we mainly use the spreading method which can obtain information of each sensor individually at the receiving side by multiplying the code with different orthogonal components in the same frequency band. In the case of multiple sensors, successive interference cancellation is used to remove interference from other sensor and apply the RAKE method. However, in a multiple sensor communication environment, if the channel information is not perfect, the performance is reduced. In this paper, we propose a transceiver structure for multiple sensor covert acoustic communication using the spread spectrum method and RAKE method, and propose and effective receiver structure to overcome drawbacks. An actual underwater experiment was conducted to analyze the performance of the covert underwater acoustic communication. The result of experiment indicated that the transmission and receive structure proposed through the actual underwater experiment was well-suited to the communication model for covert multiple accesses. In underwater acoustic communication, there has been a lot of interest in detection and acquisition of information about multiple sensors as well as detection of information on a single sensor. However, research on multiple sensors access is lacking. In order to acquire information from each sensor in multiple sensors access underwater communication, we mainly use the spreading method which can obtain information of each sensor individually at the receiving side by multiplying the code with different orthogonal components in the same frequency band. In the case of multiple sensors, successive interference cancellation is used to remove interference from other sensor and apply the RAKE method. However, in a multiple sensor communication environment, if the channel information is not perfect, the performance is reduced. In this paper, we propose a transceiver structure for multiple sensor covert acoustic communication using the spread spectrum method and RAKE method, and propose and effective receiver struc...

HVS-based scalable image watermarking

This paper proposes a novel human vision system based, spread spectrum method to scalable image watermarking. A scalable decomposition of the watermark is spread into the entire frequency sub-bands of the wavelet decomposed image. At each wavelet sub-band, the watermark data are inserted into the selected coefficients of the sub-band in a manner that the watermark embedding visual artifact occurs in the highly textured, highly contrasted and very dark/bright areas of the image. In the lowest frequency sub-band of wavelet transform, the coefficients are selected by independent analysis of texture, contrast and luminance information. In high frequency sub-bands, the coefficient selection is done by analyzing coefficients amplitude and local entropy. The experimental results show that the watermarked test images are highly transparent and robust against scalable wavelet-based image coding even at very low bit-rate coding. The proposed approach can guarantee content authentication for scalable coded images, especially on heterogeneous networks which different users with different process capabilities and network access bandwidth use unique multimedia sources.

New Binary Code Combined with New Chaotic Map and Gold Code to Ameliorate the Quality of the Transmission

<p>While the private radio communications field has grown in recent years, the communication method known as spread spectrum name has gained much prominence. A spread spectrum method can be combined with multiple access method CDMA for dividing sequences to create multi-user communication systems with very good performance of interference between symbols.The production of the chaotic sequence in scanning system and the information system according to DS-CDMA remains a hot research problem in this study to supervise in the knowledge wireless communication. This fact is still a question in establishing the secret code random spread sequence between the transmitter and the receiver.In DS-SS’s spreading is important to embed security information.It can avoid many problems in the complex calculation of the true circle. Furthermore the pseudo chaotic is reconstructed in the conventional gold to change shape with the logical operator “XOR” the results in simulation result shows in progress.It improves also the computing speed as this can solve the new equation of the problem in the original logistic map.There certainly has a kind in design: spreading chaotic sequence, chaos with gold code; including the number of users.So these are less in number and also limit the security and to can improve the ameliorate the quality of the transmissionand performance in terms of allowable number of users.The Bit error rate (BER) performance of the system is evaluated in multi-user environment under AWGN and reveals that the DS-SS system using new binary code combined with new logistic mapand gold code to ameliorate the quality of the transmission.</p>

Spread-Spectrum Beamforming and Clutter Filtering for Plane-Wave Color Doppler Imaging.

Plane-wave imaging is desirable for its ability to achieve high frame rates, allowing the capture of fast dynamic events and continuous Doppler data. In most implementations of plane-wave imaging, multiple low-resolution images from different plane wave tilt angles are compounded to form a single high-resolution image, thereby reducing the frame rate. Compounding improves the lateral beam profile in the high-resolution image, but it also acts as a low-pass filter in slow time that causes attenuation and aliasing of signals with high Doppler shifts. This paper introduces a spread-spectrum color Doppler imaging method that produces high-resolution images without the use of compounding, thereby eliminating the tradeoff between beam quality, maximum unaliased Doppler frequency, and frame rate. The method uses a long, random sequence of transmit angles rather than a linear sweep of plane wave directions. The random angle sequence randomizes the phase of off-focus (clutter) signals, thereby spreading the clutter power in the Doppler spectrum, while keeping the spectrum of the in-focus signal intact. The ensemble of randomly tilted low-resolution frames also acts as the Doppler ensemble, so it can be much longer than a conventional linear sweep, thereby improving beam formation while also making the slow-time Doppler sampling frequency equal to the pulse repetition frequency. Experiments performed using a carotid artery phantom with constant flow demonstrate that the spread-spectrum method more accurately measures the parabolic flow profile of the vessel and outperforms conventional plane-wave Doppler in both contrast resolution and estimation of high flow velocities. The spread-spectrum method is expected to be valuable for Doppler applications that require measurement of high velocities at high frame rates.

Nested and interleaved direct sequence spread spectrum to enhance CDMA security and bit error rate performance

SummaryTwo new methods, the nested direct sequence spread spectrum and interleaved direct sequence spread spectrum, are introduced in view of the previously investigated spread spectrum methods. In the nested direct sequence method, the security is maintained, and the cross‐correlation between different codes resulting in multi‐user interference that corresponds to BER performance is improved, while in the interleaved direct sequence spread spectrum, the security is improved and BER performance is maintained. Both methods are analysed by mathematical relations as well as computer simulations and are compared with the existing methods. Copyright © 2016 John Wiley & Sons, Ltd.

Covert communications through mobile voice channels

The rapid development and growth of cellular mobile networks in recent years has made voice channels widely available almost everywhere. On the other hand, voice dedicated channels possess properties that make them ideal options for high priority real-time secure communications. Beside these realities, information embedding has gained remarkable attention in recent years due to its potential application in multimedia security. In this regard, this study aims to propose an efficient scheme for data hiding to show the feasibility of exploiting these channels for covert communications. To this end, the authors propose new suboptimal but practical schemes based on additive and multiplicative spread spectrum methods. The analytical evaluations of the proposed techniques along with simulation results show proper efficiency of these schemes. Moreover, it is shown that the proposed scheme based on the M-ary bi-orthogonal general maximum likelihood and M-ary bi-orthogonal generalised embedding of multiplicative watermarks techniques outperform the other proposed schemes in this study. Experimental evaluation confirms that the proposed data hiding scheme benefits from an acceptable level of imperceptibility. Finally, the authors propose a security block which considerably increases the robustness of proposed structures against histogram-based steganalysis.

Chaotic direct sequence spread spectrum for secure underwater acoustic communication

Direct sequence spread spectrum (DSSS) has been widely used in underwater acoustic (UWA) communications. In DSSS communications, spreading sequence’s period and chip rate are important characteristic parameters. However, these characteristic parameters may be detected in hostile environments due to the periodic nature of spreading sequence and their well-known construction process. In this paper, a novel chaotic direct sequence spread spectrum (CD3S) method is proposed for secure UWA communications. In the CD3S communications, chaotic sequences acting as encryption keys are used to encrypt the phases of transmitted signals. Consequently, the application of chaotic sequences disguises these obvious characteristic parameters of spread spectrum (SS) signals. It is difficult for unauthorized users to detect or intercept CD3S signal without knowledge of corresponding chaotic sequences. Hence, CD3S signal has a lower probability of detection and interception. Moreover, CD3S can achieve similar bit error ratio (BER) performance compared with DSSS in actual UWA communications. Also, the receivers that are suitable for DSSS communication can also be applied to CD3S communication. Numerical simulations demonstrate its excellent performance and potential applications in confidential UWA communications.

Perception-based audio watermarking scheme in the compressed bitstream

In this paper, a new perception-based watermarking scheme for MPEG-4 scalable to lossless (SLS) audio is proposed. Under the control of the psychoacoustic model, the significant part of integer modified discrete cosine transform (IntMDCT) coefficients are adaptively modified during MPEG-4 SLS audio compression taking robustness, imperceptibility and security into consideration. The chaotic watermark generated by chaos is simply embedded to ensure security. Moreover, the adaptive spread spectrum method is exploited to further tradeoff robustness and transparency of this scheme. Extensive experimental results confirm that the proposed scheme is robust against common signal processing attacks while the inaudibility of the scheme is preserved.

Spread Spectrum Codes for Continuous-Phase Modulated Systems

We study the theoretical performance of a combined approach to demodulation and decoding of binary continuous-phase modulated signals under repetition-like codes. This technique is motivated by a need to transmit packetized or framed data bursts in high noise regimes where many powerful, short-length codes are ineffective. In channels with strong noise, we mathematically study the asymptotic bit error rates of this combined approach and quantify the performance improvement over performing demodulation and decoding separately as the code rate increases. In this context, we also discuss a simple variant of repetition coding involving pseudorandom code words, based on direct-sequence spread spectrum methods, that preserves the spectral density of the encoded signal in order to maintain resistance to narrowband interference. We describe numerical simulations that demonstrate the advantages of this approach as an inner code which can be used underneath modern coding schemes in high noise environments.

Tamed Spread Spectrum Method Based on Quasi-regular LDPC Code

Tamed Spread Spectrum Method Based on Quasi-regular LDPC Code

Ultrasonic Multiple-Access Ranging System Using Spread Spectrum and MEMS Technology for Indoor Localization

Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

심리음향 분석을 이용한 MP3 저작권 보안을 위한 적응적 워터마킹

본 논문에서는 오디오 컨텐츠 저작권 보안을 위하여 MP3 공격에 강인한 워터마킹 방법을 제안한다. 일반적인 주파수 도메인에서의 워터마킹 방법인 Cox의 스프레드 스펙트럼 방법에서는 DCT후 값이 큰 저주파수의 계수에 순차적으로 워터마크를 삽입하였다. 임의의 주파수 계수에 삽입하는 방법은 효과적이지 못하므로, 본 논문에서는 심리음향 모델을 분석하여 MP3 공격시 손실이 적은 주파수 계수에 적응적인 함수를 적용하여 가중치를 부여한 후 계수에 워터마크를 삽입하는 방법을 제안한다. 다양한 음원에 대하여 실험한 결과, 제안한 방법은 기존의 방법들에 비해 워터마크의 보존하고 원본 음원의 왜곡을 줄이는 두 가지 측면 모두 좋은 결과를 나타내었다. In this paper, we suggest a new audio watermarking method for audio contents copyrights that can efficiently provide protection from MP3 compression attacks. Watermarks were inserted at the coefficients repeatedly from low frequencies to high frequencies after DCT transform in commonly used Cox's spread spectrum method. Because the methods using arbitrary coefficients are not effective, we use the new weight functions that make small losses for the watermark coefficients during attacks, using psychological acoustics. In the results of various sound clips, the suggested method had overall better outcomes than the Cox's method by preserving watermarks and reducing distortions of the original sounds.

Program Aplikasi Steganografi Menggunakan Metode Spread Spectrum pada Perangkat Mobile Berbasis Android

The exchange of traffic information in cyberspace grows fast. In all areas of life utilize technology to exchange information. One of the media owned by many people is mobile device such as mobile phone and tablet computer. In fact many people have been using mobile devices for information exchange function, and expect information to be transmitted quickly, accurately, and safely. The information security sent will be very important when the information is confidential. One way to secure information sent is the concealment of information into a media so that information hidden is beyond recognition by the human senses, which is commonly referred to steganography. This research studied and implemented steganography using spread spectrum Method on Android-based mobile devices. The results showed that the inserted image before and after the message was inserted is not different with PSNR value of about 75.

A robust spread spectrum based image watermarking in ridgelet domain

A new robust method of spread spectrum based image watermarking is proposed in this article. Spread spectrum technique and scrambling are used for increasing robustness and invisibility of the algorithm. Our suggested method is carried out using ridgelet transform as an efficient transform for representing images with line singularities. In embedding part, the host image is partitioned into non-overlapping blocks and ridgelet transform is applied to each single block. In this way, a curved edge is divided into some straight edges so that ridgelet transform shows optimal performance even for complicated images with curve edges. To embed the watermark bits, the best directions of ridgelet coefficients are selected with respect to their variance intensity. In extraction part, a computationally efficient detection method is used for detecting watermark logo blindly from distorted watermarked image. To achieve more robust algorithm firstly, we find the best place to insert the watermark bits and secondly, we encode the scrambled watermark bits by pseudo random sequences with an authentication key. Robustness of our proposed method is tested against different kinds of attacks. According to the experimental results, proposed method shows much improved performance in comparison to other published works.

Scanning electron microscope image enhancement using spread spectrum through dither signal imposition

Noise is a primary issue in obtaining an image in a scanning microscope. This noise needs to be minimized in order to have a clear image of the sample in case of a nanosize level measurement. In this work, we propose a method to improve the image quality by applying dither signal injection to the scanning signal. This method involves minimizing the noise that occurs in scan control circuits, which results in a blurry or distorted image. The collected secondary electrons are first multiplied through a photomultiplier tube and are then converted into digital form using an analog/digital (A/D) converter. We propose a solution for the noise from the scan control circuit that appears on the image by adopting the spread spectrum method.

Watermarking for Multimedia Security Using Complex Wavelets

This paper investigates the application of complex wavelet transforms to the field of digital data hiding. Complex wavelets offer improved directional selectivity and shift invariance over their discretely sampled counterparts allowing for better adaptation of watermark distortions to the host media. Two methods of deriving visual models for the watermarking system are adapted to the complex wavelet transforms and their performances are compared. To produce improved capacity a spread transform embedding algorithm is devised, this combines the robustness of spread spectrum methods with the high capacity of quantization based methods. Using established information theoretic methods, limits of watermark capacity are derived that demonstrate the superiority of complex wavelets over discretely sampled wavelets. Finally results for the algorithm against commonly used attacks demonstrate its robustness and the improved performance offered by complex wavelet transforms.