To achieve the copyright protection in digital images, watermarking is identified as a major technology to protect digital images from illegal manipulation and geometric distortions. In this paper we discuss a digital image watermarking algorithm based on Discrete Wavelet TransformDiscrete Cosine Transform -Singular Value Decomposition (DWT-DCT-SVD). Here in this paper we examined and compared various wavelet families such as Haar, Daubechies, Biorthogonal and Coiflets for the watermarking algorithm. The difference in this method, from other traditional methods is that the watermark is embedded in high frequency band. Traditionally it is assumed that for having good robustness, a watermark should be embedded in low or mid frequency.DWT provides scalability, DCT provides compression and SVD offers minimum or no distortion. Choice of wavelets depends on the choice of wavelet function as DWT can be composed of any function that satisfies requirements of multiresolution analysis. In each of these wavelet families we analyzed effects of wavelets on image quality. The simulation results show good performance with respect to robustness against various image processing operations.
Performance of selection combining (SC) receiver has been derived over two-wave diffused power (TWDP) fading channels with arbitrary and non-identical fading parameters. An expression of cumulative distribution function (CDF) of signalto-noise ratio (SNR) for TWDP fading channel has been derived, which is used to obtain the probability density function (PDF) of SNR at the output of SC receiver. The PDF of output SNR has been used to derive expressions of outage probability and average bit error rate for coherent and non-coherent modulation schemes. Effect of total number of branches M and the fading parameters K and Δ on the system performance has been studied. The obtained results are verified with the special case results available in literature and by Monte Carlo simulation.
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