check,check on 和 check up on 都包含“检查”、“核对”的意义。例如:1.checkI have checked your answers and none of them are correct.我检查了你的答案,没有一个正确。When I checked my shopping list I found I’d forgotten ...check,check on 和 check up on 都包含“检查”、“核对”的意义。例如:1.checkI have checked your answers and none of them are correct.我检查了你的答案,没有一个正确。When I checked my shopping list I found I’d forgotten to buy eggs.我核对购物单时发现忘记买蛋了。展开更多
Low-Density Parity-Check （LDPC） codes are powerful error correcting codes adopted by recent communication standards. LDPC decoders are based on belief propagation algorithms, which make use of a Tanner graph and ver...Low-Density Parity-Check （LDPC） codes are powerful error correcting codes adopted by recent communication standards. LDPC decoders are based on belief propagation algorithms, which make use of a Tanner graph and very intensive message-passing computation, and usually require hardware-based dedicated solutions. With the exponential increase of the computational power of commodity graphics processing units （GPUs）, new opportunities have arisen to develop general purpose processing on GPUs. This paper proposes the use of GPUs for implementing flexible and programmable LDPC decoders. A new stream-based approach is proposed, based on compact data structures to represent the Tanner graph. It is shown that such a challenging application for stream-based computing, because of irregular memory access patterns, memory bandwidth and recursive flow control constraints, can be efficiently implemented on GPUs. The proposal was experimentally evaluated by programming LDPC decoders on GPUs using the Caravela platform, a generic interface tool for managing the kernels＇ execution regardless of the GPU manufacturer and operating system. Moreover, to relatively assess the obtained results, we have also implemented LDPC decoders on general purpose processors with Streaming Single Instruction Multiple Data （SIMD） Extensions. Experimental results show that the solution proposed here efficiently decodes several codewords simultaneously, reducing the processing time by one order of magnitude.展开更多
针对基于无线信道特征的密钥提取技术中获得的信道特征不完全一致的问题,提出一种自适应的低密度奇偶校验码(low density parity check code,LDPC)纠正通信双方密钥不一致位的方案。测量无线信道的统计信道特征,对比密钥协商中的信道特...针对基于无线信道特征的密钥提取技术中获得的信道特征不完全一致的问题,提出一种自适应的低密度奇偶校验码(low density parity check code,LDPC)纠正通信双方密钥不一致位的方案。测量无线信道的统计信道特征,对比密钥协商中的信道特征与统计信道特征,估计信道特征的初始错误率,根据初始错误率的不同自适应地选择LPDC码的码率,可以利用统计信道特征提前对信道特征初始错误率做出判断,确定LDPC码的码率。仿真结果表明,在各个参数基本相同的情况下,使用自适应的LDPC方案可以获得更高的纠错成功率和协商效率。展开更多
QLC（Quad-Level Cell） NAND flash will be one of the future technologies for next generation memory chip after three-dimensional（3D） TLC（Triple-Level Cell） stacked NAND flash. In QLC device, data errors will easil...QLC（Quad-Level Cell） NAND flash will be one of the future technologies for next generation memory chip after three-dimensional（3D） TLC（Triple-Level Cell） stacked NAND flash. In QLC device, data errors will easily occur because of 2~4 data levels in the limited voltage range. This paper studies QLC NAND technology which is 4 bits per cell. QLC programming methods based on 16 voltage levels and reading method based on ＂half-change＂ Gray coding are researched. Because of the probable error impact of QLC NAND cell＇s voltage change, the solution of generating the soft information after XOR（exclusive OR） the soft bits by internal read mechanism is presented for Low-Density Parity-Check（LDPC） Belief Propagation（BP） decoding in QLC design for its system level application.展开更多
The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel c...The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel class of quantum Low Density Parity Check (LDPC) codes constructed from cyclic classes of lines in Euclidean Geometry (EG). The corresponding constructed parity check matrix has quasi-cyclic structure that can be encoded flexibility, and satisfies the requirement of dual-containing quantum code. Taking the advantage of quasi-cyclic structure, we use a structured approach to construct Generalized Parity Check Matrix (GPCM). This new class of quantum codes has higher code rate, more sparse check matrix, and exactly one four-cycle in each pair of two rows. Ex-perimental results show that the proposed quantum codes, such as EG(2,q)II-QECC, EG(3,q)II-QECC, have better performance than that of other methods based on EG, over the depolarizing channel and decoded with iterative decoding based on the sum-product decoding algorithm.展开更多
文摘check,check on 和 check up on 都包含“检查”、“核对”的意义。例如:1.checkI have checked your answers and none of them are correct.我检查了你的答案,没有一个正确。When I checked my shopping list I found I’d forgotten to buy eggs.我核对购物单时发现忘记买蛋了。
基金Supported by the Portuguese Foundation for Science and Technology,through the FEDER program,and also under Grant No.SFRH/BD/37495/2007
文摘Low-Density Parity-Check （LDPC） codes are powerful error correcting codes adopted by recent communication standards. LDPC decoders are based on belief propagation algorithms, which make use of a Tanner graph and very intensive message-passing computation, and usually require hardware-based dedicated solutions. With the exponential increase of the computational power of commodity graphics processing units （GPUs）, new opportunities have arisen to develop general purpose processing on GPUs. This paper proposes the use of GPUs for implementing flexible and programmable LDPC decoders. A new stream-based approach is proposed, based on compact data structures to represent the Tanner graph. It is shown that such a challenging application for stream-based computing, because of irregular memory access patterns, memory bandwidth and recursive flow control constraints, can be efficiently implemented on GPUs. The proposal was experimentally evaluated by programming LDPC decoders on GPUs using the Caravela platform, a generic interface tool for managing the kernels＇ execution regardless of the GPU manufacturer and operating system. Moreover, to relatively assess the obtained results, we have also implemented LDPC decoders on general purpose processors with Streaming Single Instruction Multiple Data （SIMD） Extensions. Experimental results show that the solution proposed here efficiently decodes several codewords simultaneously, reducing the processing time by one order of magnitude.
文摘针对基于无线信道特征的密钥提取技术中获得的信道特征不完全一致的问题,提出一种自适应的低密度奇偶校验码(low density parity check code,LDPC)纠正通信双方密钥不一致位的方案。测量无线信道的统计信道特征,对比密钥协商中的信道特征与统计信道特征,估计信道特征的初始错误率,根据初始错误率的不同自适应地选择LPDC码的码率,可以利用统计信道特征提前对信道特征初始错误率做出判断,确定LDPC码的码率。仿真结果表明,在各个参数基本相同的情况下,使用自适应的LDPC方案可以获得更高的纠错成功率和协商效率。
文摘QLC（Quad-Level Cell） NAND flash will be one of the future technologies for next generation memory chip after three-dimensional（3D） TLC（Triple-Level Cell） stacked NAND flash. In QLC device, data errors will easily occur because of 2~4 data levels in the limited voltage range. This paper studies QLC NAND technology which is 4 bits per cell. QLC programming methods based on 16 voltage levels and reading method based on ＂half-change＂ Gray coding are researched. Because of the probable error impact of QLC NAND cell＇s voltage change, the solution of generating the soft information after XOR（exclusive OR） the soft bits by internal read mechanism is presented for Low-Density Parity-Check（LDPC） Belief Propagation（BP） decoding in QLC design for its system level application.
基金Supported by the National Natural Science Foundation ofChina (No. 61071145,41074090)the Specialized Research Fund for the Doctoral Program of Higher Education (200802880014)
文摘The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel class of quantum Low Density Parity Check (LDPC) codes constructed from cyclic classes of lines in Euclidean Geometry (EG). The corresponding constructed parity check matrix has quasi-cyclic structure that can be encoded flexibility, and satisfies the requirement of dual-containing quantum code. Taking the advantage of quasi-cyclic structure, we use a structured approach to construct Generalized Parity Check Matrix (GPCM). This new class of quantum codes has higher code rate, more sparse check matrix, and exactly one four-cycle in each pair of two rows. Ex-perimental results show that the proposed quantum codes, such as EG(2,q)II-QECC, EG(3,q)II-QECC, have better performance than that of other methods based on EG, over the depolarizing channel and decoded with iterative decoding based on the sum-product decoding algorithm.
