All-Digital Self-Interference Cancellation in Zero-IF Full-Duplex Transceivers

In this paper,a general scheme in digital self-interference cancellation at baseband for zero-IF full-duplex transceivers is presented. We model the self-interference signals specifically with only the nonlinear distortion signals falling in receiving band considered. A joint estimation algorithm is proposed for compensating the time delay and frequency offset taking into account the IQ amplitude and phase imbalances from mixers. The memory effect and nonlinear distortion are adaptively estimated by the de-correlated normalized least mean square(DNLMS) algorithm. Numerical simulation results demonstrate that the proposed self-interference cancellation scheme can efficiently compensate the self-interference and outperform the existing traditional solutions.

Direction-of-arrival estimation based on direct data domain (D3) method

A direction-of-arrival （DOA） estimation algorithm based on direct data domain （D3） approach is presented. This method can accuracy estimate DOA using one snapshot modified data, called the temporal and spatial two-dimensional vector reconstruction （TSR） method. The key idea is to apply the D3 approach which can extract the signal of given frequency but null out other frequency signals in temporal domain. Then the spatial vector reconstruction processing is used to estimate the angle of the spatial coherent signal source based on extract signal data. Compared with the common temporal and spatial processing approach, the TSR method has a lower computational load, higher real-time performance, robustness and angular accuracy of DOA. The proposed algorithm can be directly applied to the phased array radar of coherent pulses. Simulation results demonstrate the performance of the proposed technique.

A block-based secure and robust watermarking scheme for color images based on multi-resolution decomposition and de-correlation

This paper presents a block-based secure and robust watermarking technique for color images based on multi-resolution decomposition and de-correlation.The principal objective of the presented scheme is to simultaneously meet all the four requirements(robustness,security,imperceptibility,and capacity)of a good watermarking scheme.The contribution of this study is to basically achieve the four contradictory requirements that a good watermarking scheme must meet.To do so,different approaches are combined in a way that the four requirements are achieved.For instance,to obtain imperceptibility,the three color channels(red,green,and blue)are de-correlated using principal component analysis,and the first principal component(de-correlated red channel)is chosen for watermark embedding.Afterwards,to achieve robustness,the de-correlated channel is decomposed using a discrete wavelet transform(DWT),and the approximate band(the other three bands are kept intact to preserve the edge information)is further decomposed into distinct blocks.The random blocks are chosen based on a random generated key.The random selected blocks are further broken down into singular values and vectors.Based on the mutual dependency on singular values and vectors’matrices,the values are modified depending on the watermarking bits,and their locations are saved and used as another key,required when the watermark is to be extracted.Consequently,two-level authentication levels ensure the security,and using both singular values and vectors increases the capacity of the presented scheme.Moreover,the involvement of both left and right singular vectors along with singular values in the watermarking embedding process strengthens the robustness of the proposed scheme.Finally,to compare the presented scheme with the state-of-the-art schemes in terms of imperceptibility(peak signal-to-noise ratio and structural similarity index),security(with numerous fake keys),robustness(normalized correlation and bit error rate),and capacity,the Gonzalez and Kodak datasets are used.The comparison shows significant improvement of the proposed scheme over existing schemes.