针对LDPC(Low Density Parity Check)码分层(LBP:Layered Belief-Propagation)译码算法计算复杂度高、不易于硬件实现的问题,提出一种改进算法。该算法首先引入函数f(x)使LBP译码算法的计算复杂度大大降低;同时引入具体参数校正因子和...针对LDPC(Low Density Parity Check)码分层(LBP:Layered Belief-Propagation)译码算法计算复杂度高、不易于硬件实现的问题,提出一种改进算法。该算法首先引入函数f(x)使LBP译码算法的计算复杂度大大降低;同时引入具体参数校正因子和偏移因子,提升译码性能。仿真结果表明,改进后的算法相比LBP算法在计算复杂度降低的同时,也提升了译码性能,从而达到了易于硬件实现的目的。展开更多
从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法...从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法中初始似然比值的精确计算方法,并给出了详细的译码过程。理论分析和仿真结果表明,与目前普遍采用的APD近似非对称Gaussian统计模型下的译码性能相比较,在相同的信道条件下,该方法可以获得大约1~2 d B的性能增益。这为进一步提高自由空间光通信系统的性能提供了一定的理论依据。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
文摘针对LDPC(Low Density Parity Check)码分层(LBP:Layered Belief-Propagation)译码算法计算复杂度高、不易于硬件实现的问题,提出一种改进算法。该算法首先引入函数f(x)使LBP译码算法的计算复杂度大大降低;同时引入具体参数校正因子和偏移因子,提升译码性能。仿真结果表明,改进后的算法相比LBP算法在计算复杂度降低的同时,也提升了译码性能,从而达到了易于硬件实现的目的。
文摘从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法中初始似然比值的精确计算方法,并给出了详细的译码过程。理论分析和仿真结果表明,与目前普遍采用的APD近似非对称Gaussian统计模型下的译码性能相比较,在相同的信道条件下,该方法可以获得大约1~2 d B的性能增益。这为进一步提高自由空间光通信系统的性能提供了一定的理论依据。
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.
