This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-...This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-8PSK-quasi-semi set partitioning(CE-8PSK-Quasi-SSP).Providing the same average power,the proposed scheme can increase the minimum squared Euclidean distance(MSED)and then improve the receiving performance of BICM-ID compared with conventional symbol mapping schemes.Simultaneously,a modified iteration decoding algorithm is proposed in this paper.In the process of iteration decoding,different proportion of the extrinsic information to the systematic observations results in distinct decoding performance.At high SNR(4~9dB),the observation information plays a more important role than the extrinsic information.Simulation results show that the proportion set at 1.2 is more suitable for the novel mapping in BICM-ID.When the BER is 10^(-4),more than 0.9dB coding gain over Rayleigh channels can be achieved for the improved mapping and decoding scheme.展开更多
Secure computing paradigms impose new architectural challenges for general-purpose processors. Cryptographic processing is needed for secure communications, storage, and computations. We identify two categories of ope...Secure computing paradigms impose new architectural challenges for general-purpose processors. Cryptographic processing is needed for secure communications, storage, and computations. We identify two categories of operations in symmetric-key and public-key cryptographic algorithms that are not common in previous general-purpose workloads： advanced bit operations within a word and multi-word operations. We define MOMR （Multiple Operands Multiple Results） execution or datarich execution as a unified solution to both challenges. It allows arbitrary n-bit permutations to be achieved in one or two cycles, rather than O（n） cycles as in existing RISC processors. It also enables significant acceleration of multiword multiplications needed by public-key ciphers. We propose two implementations of MOMR： one employs only hardware changes while the other uses Instruction Set Architecture （ISA） support. We show that MOMR execution leverages available resources in typical multi-issue processors with minimal additional cost. Multi-issue processors enhanced with MOMR units provide additional speedup over standard multi-issue processors with the same datapath. MOMR is a general architectural solution for word-oriented processor architectures to incorporate datarich operations.展开更多
Aiming at shortage of the SPIHT algorithm, an improved image compression algorithm is proposed, in order to overcome the shortcomings of decoding image quality and coding time, LS9/7 lifting wavelet transform is adopt...Aiming at shortage of the SPIHT algorithm, an improved image compression algorithm is proposed, in order to overcome the shortcomings of decoding image quality and coding time, LS9/7 lifting wavelet transform is adopted. According to the characteristics of the human visual system (HVS), the scanning mode and the method to determine the threshold of algorithm are changed to improve the quality of reconstruction image. On the question of repeating scan of SPIHT algorithm, using maximum list thought, greatly reduce the computation and save operating time. The experimental results have proved that the improved algorithm of image decoding time and the quality of reconstruction images are better than the original algorithm , especially in the case of low bit rate.展开更多
基金Supported by the Key Project of Chinese Ministry of Education(No.106042)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(2007[24])
文摘This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-8PSK-quasi-semi set partitioning(CE-8PSK-Quasi-SSP).Providing the same average power,the proposed scheme can increase the minimum squared Euclidean distance(MSED)and then improve the receiving performance of BICM-ID compared with conventional symbol mapping schemes.Simultaneously,a modified iteration decoding algorithm is proposed in this paper.In the process of iteration decoding,different proportion of the extrinsic information to the systematic observations results in distinct decoding performance.At high SNR(4~9dB),the observation information plays a more important role than the extrinsic information.Simulation results show that the proportion set at 1.2 is more suitable for the novel mapping in BICM-ID.When the BER is 10^(-4),more than 0.9dB coding gain over Rayleigh channels can be achieved for the improved mapping and decoding scheme.
文摘Secure computing paradigms impose new architectural challenges for general-purpose processors. Cryptographic processing is needed for secure communications, storage, and computations. We identify two categories of operations in symmetric-key and public-key cryptographic algorithms that are not common in previous general-purpose workloads： advanced bit operations within a word and multi-word operations. We define MOMR （Multiple Operands Multiple Results） execution or datarich execution as a unified solution to both challenges. It allows arbitrary n-bit permutations to be achieved in one or two cycles, rather than O（n） cycles as in existing RISC processors. It also enables significant acceleration of multiword multiplications needed by public-key ciphers. We propose two implementations of MOMR： one employs only hardware changes while the other uses Instruction Set Architecture （ISA） support. We show that MOMR execution leverages available resources in typical multi-issue processors with minimal additional cost. Multi-issue processors enhanced with MOMR units provide additional speedup over standard multi-issue processors with the same datapath. MOMR is a general architectural solution for word-oriented processor architectures to incorporate datarich operations.
文摘Aiming at shortage of the SPIHT algorithm, an improved image compression algorithm is proposed, in order to overcome the shortcomings of decoding image quality and coding time, LS9/7 lifting wavelet transform is adopted. According to the characteristics of the human visual system (HVS), the scanning mode and the method to determine the threshold of algorithm are changed to improve the quality of reconstruction image. On the question of repeating scan of SPIHT algorithm, using maximum list thought, greatly reduce the computation and save operating time. The experimental results have proved that the improved algorithm of image decoding time and the quality of reconstruction images are better than the original algorithm , especially in the case of low bit rate.
