This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogon...This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogonal Frequency Division Multiplexing （ CI/OFDM） and Pseudo-Orthogonal Carrier lnterferometry OFDM （PO-CI/OFDM）. That can improve the signal processing efficiency of CI/OFDM and PO-CI/OFDM systems by about 2N/log2N and 2N/（ 1 ＋ log2 N） times respectively and dose not make any difference to the system function and performance. Moreover, the effi- ciency benefits will increase with the increase of the number of sub-carriers. In addition to that, we point out that the transmitter of CI/OFDM is actually technically equivalent to that of a single-carrier system with cyclic-prefix and the receiver of CI/OFDM is a typical OFDM receiver with CI despreading. Hence the low Peak-to-Average Power Ratio （PA- PR） property and high anti-fading performance of CI/OFDM system can be well explained .展开更多
针对音频文件可逆信息隐藏算法嵌入容量小、安全性不高的问题,文中提出了一种基于码分复用(Code Division Multiplexing,CDM)的音频文件大容量可逆信息隐藏(Reversible Data Hiding,RDH)算法。所提算法采用正交扩展序列将秘密信息可逆...针对音频文件可逆信息隐藏算法嵌入容量小、安全性不高的问题,文中提出了一种基于码分复用(Code Division Multiplexing,CDM)的音频文件大容量可逆信息隐藏(Reversible Data Hiding,RDH)算法。所提算法采用正交扩展序列将秘密信息可逆地嵌入音频文件中,不但可以保障所嵌入信息的无损提取,而且能够完全恢复原始音频信号;同时,基于嵌入向量的正交特性,将机密信息叠加嵌入到原始载体图像中,在嵌入过程中,不同嵌入向量中的大部分元素相互抵消,使得所提算法在大容量信息嵌入的情况下可取得更高的音频保真能力。而且,接收方只有采用相同的嵌入向量才能实现嵌入信息的正确提取与原始音频信息的无损恢复,有效提升了算法的安全性能。实验结果表明,与其他音频可逆信息隐藏算法相比,基于码分复用(CDM)的音频文件可逆信息隐藏(RDH)算法在相同文件失真情况下具有更大的可逆信息嵌入容量。展开更多
基金Paper supported by the Teaching and Research Award Programfor Outstanding Young Professor in High Education Institute, MOE,P.R.C.
文摘This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogonal Frequency Division Multiplexing （ CI/OFDM） and Pseudo-Orthogonal Carrier lnterferometry OFDM （PO-CI/OFDM）. That can improve the signal processing efficiency of CI/OFDM and PO-CI/OFDM systems by about 2N/log2N and 2N/（ 1 ＋ log2 N） times respectively and dose not make any difference to the system function and performance. Moreover, the effi- ciency benefits will increase with the increase of the number of sub-carriers. In addition to that, we point out that the transmitter of CI/OFDM is actually technically equivalent to that of a single-carrier system with cyclic-prefix and the receiver of CI/OFDM is a typical OFDM receiver with CI despreading. Hence the low Peak-to-Average Power Ratio （PA- PR） property and high anti-fading performance of CI/OFDM system can be well explained .
文摘针对音频文件可逆信息隐藏算法嵌入容量小、安全性不高的问题,文中提出了一种基于码分复用(Code Division Multiplexing,CDM)的音频文件大容量可逆信息隐藏(Reversible Data Hiding,RDH)算法。所提算法采用正交扩展序列将秘密信息可逆地嵌入音频文件中,不但可以保障所嵌入信息的无损提取,而且能够完全恢复原始音频信号;同时,基于嵌入向量的正交特性,将机密信息叠加嵌入到原始载体图像中,在嵌入过程中,不同嵌入向量中的大部分元素相互抵消,使得所提算法在大容量信息嵌入的情况下可取得更高的音频保真能力。而且,接收方只有采用相同的嵌入向量才能实现嵌入信息的正确提取与原始音频信息的无损恢复,有效提升了算法的安全性能。实验结果表明,与其他音频可逆信息隐藏算法相比,基于码分复用(CDM)的音频文件可逆信息隐藏(RDH)算法在相同文件失真情况下具有更大的可逆信息嵌入容量。
