Linghua Zhang

Researches on echo kernels of audio digital watermarking technology based on echo hiding

Echo hiding is a digital audio watermarking technology which uses the human ears time-domain masking effects. In this paper, we proposed a new echo kernel with several echoes as an alternative to the single echo in conventional echo hiding. The proposed method introduced multiple small echoes instead of a single echo, the total energy of echo pulses will be distributed to each small component of the echo. For every single echo, the magnitude will be reduced, and it carries less energy. But the total energy embedded in increases, with the premise of ensuring the imperceptibility of the original audio. Therefore, the proposed method is more robust to common signal processing operations and resistant to tampering, comparing with the case of conventional echo hiding method. Also, in subjective evaluation the proposed method showed quite good perceptual quality.

Power-Constrained Secrecy Rate Maximization for Joint Relay and Jammer Selection Assisted Wireless Networks

In this paper, we examine the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward protocol is considered. We propose a new joint relay and jammer selection (JRJS) scheme for protecting wireless communications against eavesdropping, where an intermediate node is selected as the relay for the sake of forwarding the source signal to the destination and meanwhile, the remaining intermediate nodes are employed to act as friendly jammers, which broadcast the artificial noise for disturbing the eavesdropper. We further investigate the power allocation among the source, relay and friendly jammers for maximizing the secrecy rate of proposed JRJS scheme, and derive a closed-form sub-optimal solution. Specifically, all the intermediate nodes, which successfully decode the source signal, are considered as relay candidates. For each candidate, we derive the sub-optimal closed-form power allocation solution and obtain the secrecy rate result of the corresponding JRJS scheme. Then, the candidate, which is capable of achieving the highest secrecy rate, is selected as the relay. Two assumptions about the channel state information (CSI), namely the full CSI (FCSI) and partial CSI (PCSI), are considered. Simulation results show that the proposed JRJS scheme outperforms the conventional pure relay selection, pure jamming, and generalized singular-value-decomposition-based beamforming schemes in terms of secrecy rate. Additionally, the proposed FCSI-based power allocation and PCSI-based power allocation schemes both achieve higher secrecy rates than the equal power allocation scheme.

Optimal Power Allocation for Physical-Layer Security Using Joint Relay and Jammer Selection

In this paper, we propose a new joint relay and jammer selection (JRJS) scheme to enhance the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward (DF) protocol is considered. In the proposed JRJS scheme, an ntermediate node is selected as the relay for data transmission, while the others are used to act as friendly jammers for disrupting the eavesdropper by broadcasting artificial noise. We focus on the power allocation between the relay and jammers to maximize the secrecy rate of proposed JRJS scheme under a total transmit power constraint, and derive a closed-form optimal power allocation solution. For the purpose of comparision, the conventional pure relay selection and pure jammer selection schemes are considered as benchmark schemes. Simulation results show the advantage of the proposed JRJS scheme over conventional pure relay selection and pure jammer selection methods in terms of secrecy rate. Additionally, the derived optimal power allocation solution leads to a significantly higher secrecy rate than the equal power allocation scheme.

A digital audio watermarking algorithm based on block encoding

Firstly we introduce Hearing Masking Properties, the principle of cepstrum and backward and forward kernels, and then we propose a new scheme. The proposed scheme improve recovery rate at the expense of lowing the maximum communication rate. Whats more, we compare the conventional system with our proposed system by adding white noise, filtering, re-sampling and also altering attenuation coefficient, the delay time, and the communication rate. We also do experiments on audio quality. Experiments demonstrate that the proposed scheme is suitable in the situation in which we need high the recovery rate.

Optimal power allocation for joint cooperative beamforming and jamming assisted wireless networks

In this paper, we examine the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward (DF) protocol is considered. We propose a new joint cooperative beamforming and jamming (JCBJ) scheme to protect wireless communication against eavesdropping, where the intermediate nodes which successfully decode the source signal are selected as the relays for simultaneously forwarding the source signal by employing a weight vector, and meanwhile, the others are used to act as the friendly jammers for broadcasting artificial noise to disturb the eavesdropper. We further investigate the optimal power allocation among the source, relays and friendly jammers for maximizing the secrecy rate of the proposed JCBJ scheme and derive a closed-form sub-optimal solution. Simulation results show that the proposed JCBJ scheme achieves obviously higher secrecy rate than the conventional generalized singular-value-decomposition (GSVD) based beamforming and pure jamming schemes. Additionally, the proposed optimal power allocation scheme performs much better than the equal power allocation scheme in terms of secrecy rate.

Joint Cooperative Beamforming and Jamming for Physical-Layer Security of Decode-and-Forward Relay Networks

This paper proposes a new joint cooperative beamforming and jamming (JCBJ) scheme for improving the physical layer security of decode-and-forward wireless networks where a source node transmits to its destination with the aid of multiple intermediate nodes in the presence of an eavesdropper. In the proposed JCBJ scheme, we select the intermediate nodes succeeding in source decoding as the relays to forward the source transmission simultaneously by employing a beamforming weight vector, and meanwhile, use the remaining ones as the friendly jammers to disturb the eavesdropper by sending artificial noise. In order to achieve the secrecy rate maximum, we further study on the power allocation among the source, relays, and jammers under two assumptions of the wiretap link’s channel state information. We derive the closed-form optimal solutions by first allocating the transmit power at the source within different ranges to consider all the possible relay selection schemes in which different numbers of relays are employed, and then transforming the multivariable power allocation problem to a set of single-variable optimization sub-problems. Our numerical results show the superiority of the proposed JCBJ scheme and the proposed power allocation strategies.

A pitch state dependent dictionary design method for single-channel speech separation

In this paper, we propose to design a new pitch state dependent dictionary to perform single-channel speech separation. The dictionary is designed in two stages, which are sub-dictionary learning and sub-dictionary concatenation. In sub-dictionary learning, pitch state information is taken into account to learn a set of discriminative sub-dictionaries for each speaker in time-domain. To be specific, each sub-dictionary is generated as a matrix composed of the speakers training frames of similar pitch states as columns. Moreover, we utilize a frequent pattern mining method to further reduce the sub-dictionary size. In sub-dictionary concatenation, we propose to select an appropriate weight pair to match the learned sub-dictionaries to generate a dictionary for separation. Experimental results show that the proposed method achieves better overall performance than two dictionary-based methods and a source-filter-based method also using pitch information.

Compressive sensing based visual tracking using multi-task sparse learning method

In this paper, we propose a compressive sensing based framework for robust visual tracking. As a key part of the tracking framework, a new multi-task sparse learning method is designed to estimate the observation likelihood in order to determine the best target. Compared with the traditional multi-task sparse learning method, our method uses compressed appearance features to achieve multi-task sparse representation. Experimental results show that the proposed visual tracking framework can achieve a better tracking performance than state-of-the-art tracking methods with a significantly reduced computational complexity.

A Chinese speech compensation method for the leakage based on generalized sidelobe canceller in hearing aids

In this paper, the leak of speech caused by generalized sidelobe canceller beamformer algorithm is analyzed from the view of Chinese. A Chinese speech processing technology is proposed to compensate the leak of speech. Amplitude spectrum envelope was modified to improve the similarity between spectrum envelope and the pitch contour with the information of pitch contour. Considering that the speech signal has a great loss in the high frequency range, as a characteristic of the leak information, a consonant amplification method could raising the energy of voiceless consonant, reducing the energy section of the noise and improve speech intelligibility without changing the formant structure. The results show that the signal after the algorithm treatment improved the intelligibility of speech.