Showing papers in "Aeu-international Journal of Electronics and Communications in 2014"

A novel blind robust image watermarking in DCT domain using inter-block coefficient correlation

Abstract: This paper presents a novel blind watermarking algorithm in DCT domain using the correlation between two DCT coefficients of adjacent blocks in the same position. One DCT coefficient of each block is modified to bring the difference from the adjacent block coefficient in a specified range. The value used to modify the coefficient is obtained by finding difference between DC and median of a few low frequency AC coefficients and the result is normalized by DC coefficient. The proposed watermarking algorithm is tested for different attacks. It shows very good robustness under JPEG image compression as compared to existing one and also good quality of watermark is extracted by performing other common image processing operations like cropping, rotation, brightening, sharpening, contrast enhancement etc.

Improved algorithm for image encryption based on DNA encoding and multi-chaotic maps

Abstract: New image encryption based on DNA encoding combined with chaotic system is proposed. The algorithm uses chaotic system to disturb the pixel locations and pixel values and then DNA encodings according to quaternary code rules are carried out. The pseudo DNA operations are controlled by the quaternary chaotic sequences. At last the image encryption through DNA decoding is achieved. The theoretical analysis and experimental results show that the algorithm improves the encoding efficiency, enhances the security of the ciphertext, has a large key space and a high key sensitivity, it is able to resist the statistical and exhaustive attacks.

Linear antenna array synthesis using cat swarm optimization

Abstract: Antenna arrays with high directivity and low side lobe levels need to be designed for increasing the efficiency of communication systems. A new evolutionary technique, cat swarm optimization (CSO), is proposed for the synthesis of linear antenna arrays. The CSO is a high performance computational method capable of solving linear and non-linear optimization problems. CSO is applied to optimize the antenna element positions for suppressing side lobe levels and for achieving nulls in desired directions. The steps involved in the problem formulation of the CSO are presented. Various design examples are considered and the obtained CSO based results are validated by comparing with the results obtained using particle swarm optimization (PSO) and ant colony optimization (ACO). The flexibility and ease of implementation of the CSO algorithm is evident from this analysis, showing the algorithm's usefulness in electromagnetic optimization problems.

Positive/negative lossy/lossless grounded inductance simulators employing single VDCC and only two passive elements

Abstract: Actively simulated grounded inductors have been used in several applications ranging from filter to oscillator design as well as cancellation of parasitic inductances. In this paper, new grounded inductance simulators employing only one voltage differencing current conveyor (VDCC) and two passive components are proposed. Two new topologies for realizing positive and negative lossless inductances and four different topologies for realizing lossy inductances are proposed. The aim of this paper is to present new inductance simulators using the minimum number of active and passive components. The proposed inductance simulators can be tuned electronically by changing the biasing current of the VDCC. Moreover, the circuits do not require any conditions of component matching. Finally, using one of the proposed inductance simulators a third-order high-pass filter is constructed. The performance of the proposed filter is verified and simulated by using SPICE.

Chaos-based color image block encryption scheme using S-box

Abstract: A chaos-based color image encryption scheme using bijection is designed. The whole image is diffused by exclusive or (XOR) operation for random rounds, each color component is separated into blocks with the same size. A bijective function f : B → S between block set B and S-box set S , is built. The corresponding 8 × 8 S-box is dynamically generated by the Chen system with variable conditions. The ciphered image can be obtained after substituting each block with the paired S-box. Numerical simulation and security analysis demonstrate that the scheme is practical in image encryption.

A fast and efficient color image enhancement method based on fuzzy-logic and histogram

Abstract: A new fuzzy logic and histogram based algorithm for enhancing low contrast color images has been proposed here. The method is computationally fast compared to conventional and other advanced enhancement techniques. It is based on two important parameters M and K , where M is the average intensity value of the image, calculated from the histogram and K is the contrast intensification parameter. The given RGB image is converted into HSV color space to preserve the chromatic information contained in the original image. To enhance the image, only the V component is stretched under the control of the parameters M and K . The proposed method has been compared with conventional contrast enhancement techniques as well as with advanced algorithms. All the above techniques were based on the principle of transforming the skewed histogram of the original image into a uniform histogram. The performance of the different contrast enhancement algorithms are evaluated based on the visual quality, Tenengrad, CII and the computational time. The inter comparison of different techniques was carried out on different low contrast color images. Based on the performance analysis, we advocate that our proposed Fuzzy Logic method is well suited for contrast enhancement of low contrast color images.

Bulk-driven floating-gate and bulk-driven quasi-floating-gate techniques for low-voltage low-power analog circuits design

Abstract: In this paper, novel non-conventional techniques, 1 named by the author of this paper “bulk-driven floating-gate (BD-FG)” MOS transistor (MOST) and “bulk-driven quasi-floating-gate (BD-QFG) MOST” for low-voltage (LV) low-power (LP) analog circuit design are presented. These novel techniques appear as a good solution to merge the advantages of floating-gate (FG) and quasi-floating-gate (QFG) with the advantages of bulk-driven (BD) technique and suppress their disadvantages. Consequently, the transconductance and transient frequency of BD-FG and BD-QFG MOSTs approach the conventional gate driven (GD) MOST values. Furthermore, a novel LV LP class AB second generation current conveyor based on BD-FG MOST is presented in this paper as an example. The supply voltage is only ±0.4 V with a rail-to-rail voltage swing capability and total power consumption of mere 10 μW. PSpice simulation results using the 0.18 μm P-well CMOS technology are included to confirm the attractive properties of these new techniques.

Self-adaptive permutation and combined global diffusion for chaotic color image encryption

Abstract: As to color image encryption, most of the previous algorithms are to encrypt its R, G, B components, respectively, which neglected the correlations among R, G, B components. To overcome this problem, a type of chaotic color encryption scheme was proposed by Wang et al. based on combined permutation and combined diffusion. Unfortunately, there are some drawbacks in the scheme and it has been cryptanalyzed soon. To strength the security performance, a new scheme based on coupled logistic map, self-adaptive permutation, S8 S-boxes transform and combined global diffusion is proposed in this paper. Simulation results and analyses show that our cryptosystem is immune to some well-known attacks and has high security for practical color image encryption applications.

CMOS ring oscillator with combined delay stages

Abstract: Full transistor voltage control oscillators by delay stages are studied in this paper. First we describe the general conditions of oscillators and after introducing some common inverters, calculating their delay times, we analyze the dependence of delay time to variation of power supply voltage. The analyzing results show that the delay of basic type inverter varies in the opposite direction as that of current starved inverter, therefore to achieve better frequency stability versus voltage power supply changing, some combined structures of inverters are presented. The results of simulation by 0.18 CMOS technology library of HSPICE approve the analysis results.

Design and analysis of DC gain and transconductance boosted recycling folded cascode OTA

Abstract: A new technique for improving the transconductance and low frequency output impedance of recycling folded cascode (RFC) amplifiers is presented. This enhancement was achieved by using a positive feedback and upgrading the recycling structure. The new structure profits from better transconductance, slew rate, and DC gain in comparison with conventional folded cascode (FC) amplifier. Moreover, the input referred noise is reduced and the phase-margin improved. The enhanced amplifier, simulated in 0.18 μm CMOS technology, exhibits a DC gain enhancement of 16.3 dB as well as 115.5 MHz increase in gain bandwidth compared to conventional FC configuration. The amplifier consumes 360 μW @ 1.2 V which makes it suitable for low-voltage applications.

Image fusion based on shearlet transform and regional features

Abstract: In this paper, a new image fusion method is proposed based on the shearlet transform. In this method, to make the best use of the regional characteristics of the low frequency coefficients, the low frequency sub-band coefficients from different images are fused according to a rule based on regional energy. As for the high frequency sub-band coefficients, they are fused according to a novel rule upon comprehensive consideration of multiple regional features, such as regional variance, regional average gradient, regional spatial frequency. Experimental results show that the proposed algorithm for image fusion outperforms traditional ones.

Analysis and design of wide band Microstrip-line-fed antenna with defected ground structure for Ku band applications

Abstract: A wide band Microstrip antenna is proposed for Ku band applications with defected ground structure. A circular shape defect is integrated in the ground plane. A novel equivalent circuit model is proposed for Microstrip patch antenna with defected ground structure. Accurate design equations are presented for the wideband Microstrip antenna and theoretical analysis is done for the proposed structure. The proposed antenna has an impedance bandwidth of 56.67% ranging from 9.8 GHz to 17.55 GHz, which covers Ku-band and partially X-band. The antenna shows good radiation characteristics within the entire band, and has a gain ranging from 5 dBi to 12.08 dBi. Minimum isolation between co-polar and cross-polarization level of 20 dB and 15 dB is achieved in H-plane and E-plane respectively. The simulation of the proposed antenna is done on HFSS v.14, and measured results of fabricated antenna are in good agreement with the theoretical and simulated results.

Lossless grounded inductance simulator employing single VDBA and its experimental band-pass filter application

Abstract: Actively simulated grounded inductors have been used in several applications ranging from filter to oscillator design as well as cancelation of parasitic inductances. In this paper, new lossless grounded inductance simulator employing only one voltage differencing buffer amplifier (VDBA) and two passive components is proposed. The aim of this paper is to present new inductance simulator using the minimum number of active and passive components. The proposed inductance simulator can be tuned electronically by changing the transconductance of the VDBA. Finally, using the proposed inductance simulator a band-pass filter is constructed. The performance of the filter is simulated by using PSPICE and simulation results are verified experimentally.

Image denoising and quality measurements by using filtering and wavelet based techniques

Abstract: An image is often corrupted by noise in its acquisition and transmission by various kinds of noises. Image denoising using thresholding methods find appropriate values (threshold) which separates noise values to actual image values without affecting the significant features of the image. Wavelet transform represents image energy in compact form and representation helps in determining threshold between noisy features and important image feature. In this paper we have worked with denoising of salt–pepper and Gaussian noise. The work is organized in four steps as follows: (1) image is denoised by filtering method, (2) image is denoised by wavelet based techniques using thresholding, (3) hard thresholding and filtering method applied simultaneously on noisy image, (4) results of PSNR (peak signal to noise ratio) and MSE (mean square error) are calculated by comparing all cases.

Pointing error effects on performance of free-space optical communication systems using SC-QAM signals over atmospheric turbulence channels

Abstract: In this paper, we theoretically analyze pointing error effects on performance of free-space optical (FSO) communication systems using subcarrier intensity quadrature amplitude modulation (SC-QAM) signals over atmospheric turbulence channels. Unlike previous studies, we take into account both atmospheric turbulence channels and the pointing error effect. In order to model atmospheric turbulence channels, we employ a log-normal distribution for weak-to-moderate turbulent condition and a gamma–gamma distribution for strong turbulent condition. Moreover, we study the pointing error effect by taking into account the influence of beamwidth, aperture size and jitter variance. In addition, we use a combination of these models to analyze the combined effect of atmospheric turbulence and pointing error to FSO/SC-QAM systems. Finally, we derive analytical expressions to evaluate the average symbol error rate (ASER) performance of such systems. Numerical results present the impact of pointing error on the performance of FSO/SC-QAM systems and how we use proper values of aperture size and beamwidth to improve the performance of such systems. In addition, simulation results of FSO/SC-QAM performance over strong atmospheric turbulence and pointing errors show that the closed-form expression can provide a precision for evaluating ASER of such systems.

Design and analysis of implantable CPW fed bowtie antenna for ISM band applications

Abstract: A novel implantable coplanar waveguide (CPW) fed crossed bowtie antenna is proposed for short-range biomedical applications. The antenna is designed to resonate at 2.45 GHz, one of the industrial-scientific-medical (ISM) bands. It is investigated by use of the method of moments design equations and its simulation software (IE3D version 15). The size of the antenna is 371.8 mm 3 (26 mm × 22 mm × 0.65 mm). The simulated and analyzed return losses are −23 and −25 dB at the resonant frequency of 2.45 GHz. We have analyzed some more performances of the proposed antenna and the results show that the proposed antenna is a perfect candidate for implantation. The proposed antenna has substantial merits like low profile, miniaturization, lower return loss and better impedance matching with high gain over other implanted antennas.

A low power current controllable single-input three-output current-mode filter using MOS transistors only

Abstract: A novel circuit configuration for the realization of low power single-input three-output (SITO) current mode (CM) filters employing only MOS transistors are presented. The proposed circuit can realize low-pass (LP), band-pass (BP) and high-pass (HP) filter functions simultaneously at three high impedance outputs without changing configuration. Despite the other previously reported works, the proposed circuit is free from resistors and passive capacitors. Instead of passive capacitors; the gate-source capacitor of MOS transistor is used making the proposed circuit ideally suitable for integration. Compared to other works, the proposed filter has also the lowest number of transistors and lowest power consumption. The proposed circuit exhibits low-input and high-output impedances, which is highly desirable for cascading in CM signal processing. Moreover, it is center frequency can be electronically adjusted using a control current without a significant effect on quality factor (Q) granting it the highly desirable capability of electronic tunability. Transfer functions of the LP, BP and HP outputs are derived and the performance of the proposed circuit is proved through pre layout and post layout simulations at supply voltage of 1.8 V and using 0.18 μm CMOS process parameters. The power consumption and the required chip area are only 0.5 mW and 77.4 μm × 70.2 μm, respectively.

Craziness based particle swarm optimization algorithm for IIR system identification problem

Abstract: In this paper a variant of particle swarm optimization (PSO), called craziness based particle swarm optimization (CRPSO) technique is applied to the infinite impulse response (IIR) system identification problem. A modified version of PSO, called CRPSO adopts a number of random variables for having better and faster exploration and exploitation in multidimensional search space. Incorporation of craziness factor in the basic velocity expression of PSO not only brings diversity in particles but also ensures convergence to optimal solution. The proposed CRPSO based system identification approach has alleviated from the inherent drawbacks of premature convergence and stagnation, unlike real coded genetic algorithm (RGA), particle swarm optimization (PSO) and differential evolution (DE). The simulation results obtained for some well known benchmark examples justify the efficacy of the proposed system identification approach using CRPSO over RGA, PSO and DE in terms of convergence speed, unknown plant coefficients and mean square error (MSE) values produced for both the same order and reduced order models of adaptive IIR filters.

Fast switching based median–mean filter for high density salt and pepper noise removal

Abstract: This paper proposes a fast switching based median–mean filter for high density salt and pepper noise in images. The extreme minimum value and extreme maximum value of the noisy image are used to identify the noise pixels. In the filtering stage, the corrupted pixel is replaced either by median value or mean value based on the number of noise free pixels in the filtering window. The qualitative and quantitative results show that the proposed filter outperforms the other switching based filters namely ACWMF, PSMF, AMF, DBA and MDBUTMF in terms of noise removal and edge preservation for noise densities varying from 10% to 90%.

Security analyses of the watermarking scheme based on redundant discrete wavelet transform and singular value decomposition

Abstract: This study analyzes the recent image watermarking schemes based on redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD), and shows that in fact they are insecure and cannot be used for protecting the rightful ownership. The RDWT-SVD watermarking directly embeds a grayscale watermark image of the same size with the host image into the singular value matrix of the RDWT-transformed host image, then produces the left and right orthogonal matrices as side information which is later used in the watermark extraction stage. The RDWT-SVD approach enjoys the advantage of the RDWT redundancy to achieve a high embedding capacity, and preserves the watermark imperceptibility by exploiting the SVD stability properties. It is claimed that RDWT-SVD watermarking is robust against several common image processing and geometrical attacks, yet a fundamental flaw in the RDWT-SVD scheme is found, which leads to severe the false positive issue. Three vulnerable attacks should be considered in the RDWT-SVD scheme: (1) An attacker can easily claim the owner watermarked image; (2) the owner has the ambiguity because of the wrong side information usage, and (3) the owner can extract the correct watermark from arbitrary image. Thus, it is important to highlight these attacks when implementing the RDWT-SVD watermarking scheme.

CCII based more tunable voltage-mode all-pass filters and their quadrature oscillator applications

Abstract: In this paper, two new voltage-mode (VM) first-order all-pass filters using single active element namely second-generation current conveyor (CCII) and a grounding capacitor are proposed. The first proposed filter employs a dual output CCII (DO-CCII) and the other one uses a modified minus type CCII (MCCII−). One of the main advantages of both configurations is their high input impedances; thus, both can be easily cascaded with other VM circuits. Additionally, the use of a grounded capacitor in both circuits provides suitability for integrated circuit (IC) fabrication process. However, both of the proposed circuits need a single passive component matching constraint. Non-ideality analysis is performed for the proposed circuits. Moreover, two quadrature oscillator applications of the proposed filters are given. The behavior of the filters is verified by SPICE simulations. Also, experimental tests using commercially available ICs (AD844s) are achieved for the second proposed configuration.

Cooperative spectrum sensing for cognitive radio networks in the presence of smart malicious users

Abstract: Cognitive radio (CR) signaling imposes some threats to the network. One of these common threats is commonly referred to as primary user emulation attack, where some malicious users try to mimic the primary signal and deceive secondary users to prevent them from accessing vacant frequency bands. In this paper, we introduce a smart primary user emulation attacker (PUEA) that sends fake signals similar to the primary signal. We assume a smart attacker, in the sense that it is aware of its radio environment and may choose different transmission strategies and then, we compare it to an always present attacker. In the proposed smart attacker strategy, the occurrence of fake signal is adjusted according to the primary user activity. First, we investigate the received signal at the CR users under such attackers. Then, we formulate and derive cooperative spectrum sensing (CSS) rules for a cognitive network operating in the presence of a PUEA and propose a new spectrum sensing scheme based on energy detection. Simulation results show that our proposed method can mitigate the destructive effect of PUEA in spectrum sensing, compared to conventional energy detection spectrum sensing.

Design and analysis of UW-OFDM signals.

Abstract: Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error ratio (BER) performance of UW-OFDM, as well as comparisons to competing concepts have already extensively been discussed in previous papers. This work focuses on the different possibilities on how to generate UW-OFDM signals. The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, we present a heuristic algorithm that allows a fast numerical optimization of the redundant subcarrier positions, and we show that our original intuitive approach of spreading the redundant subcarriers in systematically encoded UW-OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions. Finally, we derive closed form approximations of the statistical symbol distributions on individual subcarriers as well as the redundant energy distribution and compare them with numerically found results.

An improved recursive and adaptive median filter for high density impulse noise

Abstract: An improved recursive and adaptive median filter (RAMF) for the restoration of images corrupted with high density impulse noise is proposed in the present paper. Adaptive operation of the filter is justified with the variation in size of working window which is centered at noisy pixels. Based on the presence of noise-free pixel(s), the size of working window changes. The noisy pixels are filtered through the replacement of their values using both noise-free pixels of the current working window and previously processed noisy pixels of that window. These processed noisy pixels are obtained recursively. The combined effort thus provides an improved platform for filtering high density impulse noise of images. Experimental results with several real-time noisy images show that the proposed RAMF outperforms other state-of-the-art filters quantitatively in terms of peak signal to noise ratio (PSNR) and image enhancement factor (IEF). The superiority of the filter is also justified qualitatively through visual interpretation.

Electronically tunable DXCCII-based grounded capacitance multiplier

Abstract: In this paper a new grounded capacitance multiplier based on DXCCII suitable for operation at low and moderate frequencies is presented. The proposed circuit employs only a single dual-X second-generation current conveyor (DXCCII) active device, used as a voltage amplifier with two NMOS transistors operating in triode region, cooperating with a floating capacitor. The realized equivalent capacitance obtained from Miller multiplication of the reference capacitor and its multiplication factor is electronically tunable. Simulation results using AMS 0.35 μm CMOS process technology parameters are included. Functionality of the proposed circuit is verified through its application in a G m -C second-order low-pass filter.

Reversible data hiding based on prediction-error histogram shifting and EMD mechanism

Abstract: This paper proposes a reversible data hiding scheme for gray-level images. The scheme exploits the similarity among adjacent pixels and uses the side-match predictors to obtain prediction-error histogram. Then secret bits are embedded by using histogram shifting method. To achieve high capacity, nonary Exploiting Modification Direction (EMD) algorithm and multi-layer embedding mechanism are used when embedding the secret bits. Additionally, we improve the method of preventing overflow and underflow problems which enhances the compression ability of location map. In the extraction process, we use the same predictors to generate the error histogram, then we can extract the secret bits and recover the original cover image. Experimental results show that our algorithm can achieve better performance compared with the previous related algorithms.

Robust semi-blind video watermarking based on frame-patch matching

Abstract: In this paper, we present a frame-patch matching based robust semi-blind video watermarking using KAZE feature. The KAZE feature is employed for matching the feature points of frame-patch with those of all frames in video for detecting the embedding and extracting regions. In our method, the watermark information is embedded in Discrete Cosine Transform (DCT) domain of randomly generated blocks in the matched region. In the extraction process, we synchronize the embedded region from the distorted video by using KAZE feature matching. Based on the matched KAZE feature points, RST (rotation, scaling, translation) parameters are estimated and the watermark information can be successfully extracted. Experimental results show that our proposed method is robust against geometrical attacks, video processing attacks, temporal attacks, and so on.

Trigonometrical approach to design a simple wideband comb compensator

Abstract: This paper presents a trigonometrical approach to design a simple second order wideband compensator of a comb decimation filter. The method is based on the similarity of the inverse passband comb characteristic and the squared sine function. The design parameter B, which is the amplitude of the squared sine function, depends only on the number K of the cascaded comb filters. Considering that the parameter B can be expressed in terms of only addition and shift operations, we may obtain a multiplierless filter. The proposed filter performs wideband compensation efficiently using a maximum of four additions/subtractions, and for a given K, can be applied to any value of the decimation factor M.

How to reconstruct end-to-end traffic based on time-frequency analysis and artificial neural network

Abstract: End-to-end traffic, which describes the inherent characteristics and end-to-end behaviors of communication networks, is the crucial input parameter of network management and network traffic engineering. This paper proposes a new reconstruction algorithm to develop the research on reconstruction of end-to-end traffic in large-scale communication networks. We firstly conduct the time-frequency analysis on end-to-end traffic, and then localize its features to gain its time-frequency properties before decomposing it into the low-frequency and high-frequency components. We find that if decomposing appropriately, the low-frequency component of end-to-end traffic can accurately reflect its change trend, while its high-frequency component can well show the burst and fluctuation nature. This motivates us to find a reasonable time-frequency decomposition strategy to extract the low-frequency and high-frequency components of end-to-end traffic. Moreover, this further inspires us to use the regressive model to model the low-frequency part, exploit artificial neural network to characterize the high-frequency component, and then combine these two parts according to the regressive model and artificial neural network to precisely reconstruct end-to-end traffic. Simulation results show that in contrast to previous methods our algorithm is much more effective and promising.

A new training strategy for neural network using shuffled frog-leaping algorithm and application to channel equalization

Abstract: This paper makes use of shuffled frog-leaping algorithm (SFLA) as a training algorithm to train multi-layer artificial neural network (ANN). Next, The SFLA ANNs are used for channel equalization. We, in this paper, also introduce SFLA for channel equalization that is formulated as an optimization problem. In short, this paper introduces a novel strategy for training of ANN and also proposes two novel approaches for channel equalization problem using shuffled frog-leaping algorithm (SFLA). The proposed strategies are tested both in time-invariant and time varying channels and interestingly yield better performance than contemporary approaches as evidenced by simulation results.