On optimization of spread spectrum watermarking with variable embedding rate

This paper proposes an improved detection algorithm for spread spectrum watermark through the realization of an efficient group combined interference cancelation (GCIC) technique. First, each watermark bit is spread over N-mutually distinct points of the cover signal and the decision variable at the decoder is formed from the weighted average of N-decision statistics. Attack channel is modeled as Rayleigh distribution followed by AWGN (additive white gaussian noise). Diversity technique is then applied to form the resultant watermarked image from the weighted average of multiple copies in order to improve detection performance where WSIR (watermark signal to interference ratio) is used as weight factor to achieve low BER (bit error rate). Genetic Algorithms (GA) is used to partition embedded bits into multiple groups, namely very strong, strong, weak and very weak based on the normalized magnitudes of their decision variables. Performance of the GA based multiple group combined interference cancelation (MGCIC) for four, three and two groups with conventional interference cancelation (IC) are then reported. A significant improvement in detection performance and capacity is seen with GA based group combined interference cancelation (GCIC) relative to conventional interference cancelation (IC) at the cost of slight increase in computation complexity. Simulation results show that bit error rate (BER) for watermark decoding is reduced as the embedded bits are divided into more number of groups and optimal partitioning of these groups are made through the use of GA.

In this paper, we propose a new digital watermarking algorithm named spatial unified key insertion (SUKI) for few-color images. By performing the adaptive threshold halftoning and contour shaping and modification, we can embed a binary logo into a digital image with superior JPEG compression resistance ability. The bit error rate (BER) of JPEG attack is equal to zero for all testing images with quality factor≥80. The BER is much lower than the traditional watermarking algorithms, such as spread spectrum watermarking and quantization index modulation watermarking. The payload is considerably high and there are no "salt-and-peppers" artifacts in the watermarked images. No additional color is introduced and the palette keeps unchanged after watermark embedding. The proposed algorithm can be applied to natural images with distinct boundaries by segmenting the images into different parts.

In this paper, we use eight transmitter antennas and eight receiver antennas as the circle antenna arrays. Shooting and bouncing ray/image(SBR/Image)techniques combining with antenna pattern are used to calculate the impulse response in indoor wireless environment. Beamforming techniques are employed to reduce the multi-path effect of the channel and bit error rate (BER). We adjust the excitation amplitude and feed length of each array element to synthesize the pattern of the antenna array by using the genetic algorithms (GA) and self-adaptive dynamic differential evolution (SADDE). Numerical results show that SADDE algorithm outperforms GA algorithm in terms of bit error rate performance and convergence speed.

We present an authentication device allowing for the validation of wireless transmissions by means of a watermark signal applied at the physical layer, and demonstrate how the method may be applied to digital broadcast television signals. The novel watermarking approach presented conveys the authentication signal through explicit emulation of innocuous channel responses, further preventing Primary User Emulation attacks in Dynamic Spectrum Access theaters. The undesirable effects of the watermark signal design are removed by the receiver by traditional channel equalization practices, resulting in nearly zero impact to the bit error rate (BER) of the primary signal received. The proposed mechanism may be implemented without modification to existing Digital Television (DTV) transmission equipment using a retrofitting approach, and does not require the modification of existing receivers or protocols. A key benefit of the proposed method is that the authentication signal may be received at a BER much lower than the primary-signal, all within original transmission power and bandwidth constraints. We discuss physical layer details of the new watermarking method, and demonstrate how proven cryptographic authentication measures may be applied to the problem.

In this paper, a new perceptual spread spectrum audio watermarking scheme is discussed. The watermark embedding process is performed in the Empirical Mode Decomposition (EMD) domain, and the hybrid watermark extraction process is based on the combination of EMD and ISA (Independent Subspace Analysis) techniques, followed by the generic detection system, i.e. inverse perceptual filter, predictor filter and correlation based detector. Since the EMD decomposes the audio signal into several oscillating components---the intrinsic mode functions (IMF)---the watermark information can be inserted in more than one IMF, using spread spectrum modulation, allowing hence the increase of the insertion capacity. The imperceptibility of the inserted data is ensured by the use of a psychoacoustical model. The blind extraction of the watermark signal, from the received watermarked audio, consists in the separation of the watermark from the IMFs of the received audio signal. The separation is achieved by a new proposed under-determined ISA method, here referred to as UISA. The proposed hybrid watermarking system was applied to the SQAM (Sound Quality Assessment Material) audio database (Available at http://sound.media.mit.edu/mpeg4/audio/sqam/ ) and proved to have efficient detection performances in terms of Bit Error Rate (BER) compared to a generic perceptual spread spectrum watermarking system. The perceptual quality of the watermarked audio was objectively assessed using the PEMO-Q (Tool for objective perceptual assessment of audio quality) algorithm. Also, using our technique, we can extract the different watermarks without using any information of original signal or the inserted watermark. Experimental results exhibit that the transparency and high robustness of the watermarked audio can be achieved simultaneously with a substantial increase of the amount of information transmitted. A reliability of 1.8 10Â?Â?Â?4 (against 1.5 10Â?Â?Â?2 for the generic system), for a bit rate of 400 bits/s, can be achieved when the channel is not disturbed.

This article presents a new estrategy to assign wavelengths in a optical link considering the four wave mixing effect in the optical fiber. The four wave mixing effect in taken into account by using a formulation that calculates the fiber noise figure for each wavelenght. We analyze the assignments when there are additions and droppings of wavelengths, considering the best and satisfactory assignments using the exhaustive and genetic algorithms, respectively. We obtain the distributions o wavelengthms from a genetic algorithm, which considers the quality of service criterion based on bit error rate. We show that our strategy is capable of determining assignments of wavelength, the maximum number of wavelengths and their positions in the grid to minimize the impact of the four wave mixing effect.

The relation between the digital watermarking and spread-spectrum is analyzed in this paper at the beginning. Then, a spread-spectrum adaptive digital watermarking scheme based on the wavelet transform is proposed and the system for this digital watermarking algorithm based on DSP is realized. Finally, a testing on the image digital watermarking processing system by DSP is conducted. The result from the testing approves that the system is flexible and can accomplish watermark embedding and detecting.

Spread spectrum watermarking (SSW) is one of the most promising watermarking techniques. While SSW is very robust against the additive noise, it suffers from an inherent noise. The noise is resulted from host interference on detection of the embedded hidden information. The host interference is one of the main reasons of relatively low embedding rate in SSW and its reduction is important. In this paper, a new method for SSW detector is proposed to reduce the host interference. The proposed method is based on the law of large numbers and symbol detection of embedded information, instead of bit detection. Since the method is based on the detection of symbols longer than 1 bit, the detector can employ PN sequences with larger length, resulting in decrease of the interference. Symbol error rate using this algorithm is calculated employing maximum a posterior criterion. Comparison of bit error rates between the modified SSW algorithm and conventional bit detection shows that the modified algorithm is much more robust against the host interference.

In terms of bit error rate (BER) and synchronization performances, Markovian codes are superior to i.i.d. codes in asynchronous mode, for the single-user case. Their BER performance is better than i.i.d. codes also in the case of multiuser detection (MUD). The paper shows that a simple code acquisition scheme based on the statistical properties of spread spectrum (SS) codes efficiently makes the performance of Markov codes superior to i.i.d. codes in asynchronous MUD systems. Hence, Markov codes are a strong candidate for being SS codes in the MUD case as well. Furthermore, the proposed code acquisition scheme significantly outperforms conventional schemes.

A novel genetic algorithm (GA) assisted minimum bit error rate (MBER) beamforming technique is introduced. The performance of the proposed GAs is characterised by the probability density function (PDF) and the mean value of the achievable bit error rate (BER) at the beamformer's output. The results are also compared to the theoretical bounds. It is shown that GAs are suitable for MBER beamforming and that a trade-off between the complexity of the GA and its robustness against system parameter variations can be found.

The carrier of the digital watermark expands from audio signals to radio frequency (RF) signals. Unlike audio signals, RF signals, such as the watermark transmission carrier, must be correctly demodulated with the watermark signals so that the distortion of the digital carrier embedded with the watermark is associated with the change in bit error rate. Based on the spread spectrum watermarking scheme, the distortion of the digital carrier signal is redefined, and the channel capacity expression of the watermarking scheme is derived. In addition, the optimal parameters to achieve the maximal channel capacity are discussed, and the constraint relation between the channel capacity and the allowable distortion is investigated.

In this research work, we have developed a communication system (transmitter / receiver) to control peak to average power (PAPR) with small bit error rate (BER) for a 4G system called multicode code division multiple access (MCCDMA). Proposed communication system works on modified Reed Muller encoded data (MRMED) string. In MRMED data is first encoded with Reed Muller (RM) code. Thereafter, encoded RM message is XORed with optimal binary string, which results lower Peak to Average Power ratio (PAPR). A well-known fact is that, bit error rate (BER) is the best performance measurement tool for a communication system. To check the integrity of our communication system, we have run the simulation for monitoring BER using MRMED sequence. Simulation work conducted, with multipath Rayleigh fading, Minimum Shift Keying (MSK) modulation and several orders of RM codes. Our results show that implementing MRMED sequences of the suggested MCCDMA communication structure, returns noticeable lower BER. For instance, in case of RM(1,4), that has error improvement proficiency of 3 (three) errors , returns BER = 8.2x10−5 adopting MSK, at SNR = 12dB. Similarly, for RM(2,3), which has error improvement efficiency of 0 error and shows distinct BER of 4.9x10−4 at 12dB (SNR).In addition to using simulation for checking BER performance of our communication system, we have also shown in our results that, as the error improvement capability of different RM codes surges, correspondingly we get a lower BER.

In this paper, an analytical and simulated approach has been developed for evaluating the performance of Bit Error Rate (BER) of Direct Sequence Spread Spectrum (DSSS). It is also demonstrated in this paper that how BER can be minimised using Rate Transition techniques. The work uses effective spreading sequence to achieve variable data rate transmission. In this research work, blind detection of the user signal has been considered assuming the receiver has prior knowledge of the user’s spreading code and is synchronised by using increased matched filter gain. Thus, it is not required to control the information to be transmitted along with the user signal. An attempt has also been made to show that how bandwidth utilisation has been halved using multirate techniques. This innovative research findings make use of implementing an efficient DSSS with reduced BER.

In this paper, a proposed method for hiding secret data in audio file (.WAV) is introduced.Genetic algorithm has been hybridized with conjugate gradient algorithm which is one of the methods for solving nonlinear unconstrained minimization problem, the hybrid genetic algorithm is used to determine the optimum positions for Least significant bit (LSB) by substituting the least significant bit of each sampling point with a binary message.Numerical results for the proposed hybrid genetic algorithm on three test function were reported and compared with the results of genetic algorithm, also two measures were used such as BER (Bit Error Rate) and MSE (Mean Square Error) in order to access the performance of the proposed steganography method.(.Wav) Least Significant Bit (LSB) . Mean Square Error ( MSE )Error Rate (BER), .

Multicarrier transmission techniques like multicarrier code division multiple access (MC-CDMA) is the strongest contender for the future generation wireless networks which is supposed to cater to the need of very high data rate with mobility and at the same time combat multipath and intersymbol interference in a spectrally efficient manner. To enhance the spectral efficiency further, some form of adaptive modulation is being proposed (Wasantha et al. (2002)). In this paper, first of all, we simulate the performance of various single-h continuous phase modulation (CPM) schemes in an MC-CDMA system by varying the two CPM parameters - size of symbol alphabet (M) and modulation index (h). The parameter sets considered are {M=2, h=0.5}, {M=2, h=0.875}, {M=4, h=0.5} and {M=4, h=0.875}. Simulation results show that the higher order modulation schemes (M=4) need better channel conditions than the lower order schemes (M=2) for a given bit error rate (BER). Moreover, as expected (Xiong (2000)), h=0.875 (approximate optimum value) gives a better BER performance than h=0.5 for a given BER. Based on these simulation results, we then design two adaptive modulation based systems, one considering h=0.5 and the other with h=0.875, each with M=2 and 4. Results of the adaptive systems clearly indicate that the adaptive switching of the modulation formats in each of these two systems increases the system capacity per given bandwidth (spectrum efficiency) effectively without sacrificing the expected BER performance. Also, it is seen that the adaptive system with h=0.875 is superior to the h=0. 5 system, both in terms of BER performance and the number of simultaneous users, but obviously at the cost of reduced bandwidth efficiency as higher the value of h, the higher bandwidth it requires.