Bloom filter(BF)is a space-and-time efficient probabilistic technique that helps answermembership queries.However,BF faces several issues.The problems with traditional BF are generally two.Firstly,a large number of fa...Bloom filter(BF)is a space-and-time efficient probabilistic technique that helps answermembership queries.However,BF faces several issues.The problems with traditional BF are generally two.Firstly,a large number of false positives can return wrong content when the data is queried.Secondly,the large size of BF is a bottleneck in the speed of querying and thus uses large memory.In order to solve the above two issues,in this article,we propose the check bits concept.From the implementation perspective,in the check bits approach,before saving the content value in the BF,we obtain the binary representation of the content value.Then,we take some bits of the content value,we call these the check bits.These bits are stored in a separate array such that they point to the same location as the BF.Finally,the content value(data)is stored in the BF based on the hash function values.Before retrieval of data from BF,the reverse process of the steps ensures that even if the same hash functions output has been generated for the content,the check bits make sure that the retrieval does not depend on the hash output alone.This thus helps in the reduction of false positives.In the experimental evaluation,we are able to reduce more than 50%of false positives.In our proposed approach,the false positives can still occur,however,false positives can only occur if the hash functions and check bits generate the same value for a particular content.The chances of such scenarios are less,therefore,we get a reduction of approximately more than 50%false positives in all cases.We believe that the proposed approach adds to the state of the art and opens new directions as such.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
以信息节点的幅度和作为校验方程的可靠度信息,提出两种简单高效的低密度奇偶效验(low density parity check,LDPC)码的加权比特翻转(weighted bit flipping,WBF)译码算法。仿真结果表明,在加性高斯白噪声信道下,误比特率为10-5时,相比...以信息节点的幅度和作为校验方程的可靠度信息,提出两种简单高效的低密度奇偶效验(low density parity check,LDPC)码的加权比特翻转(weighted bit flipping,WBF)译码算法。仿真结果表明,在加性高斯白噪声信道下,误比特率为10-5时,相比于传统的WBF和改进型WBF(modified WBF,MWBF)算法,提出的一种算法可分别获得约1.65dB和1.31dB的增益。同时,平均迭代次数也大大降低。展开更多
为了研究Polar码在编码调制(CM)系统中的性能,提出了一种基于Polar码的比特交织编码调制(BICM)系统.分析了高斯白噪声(AWGN)信道中不同调制方式对系统误比特率(BER)性能的影响,并将所提系统的BER性能与基于低密度奇偶校验(LDPC)码的BIC...为了研究Polar码在编码调制(CM)系统中的性能,提出了一种基于Polar码的比特交织编码调制(BICM)系统.分析了高斯白噪声(AWGN)信道中不同调制方式对系统误比特率(BER)性能的影响,并将所提系统的BER性能与基于低密度奇偶校验(LDPC)码的BICM系统性能进行了对比.仿真结果表明,在QPSK调制下,基于Polar码的BICM系统与基于Polar码的无编码调制系统的BER曲线几乎完全重合;而在16QAM调制下,当码长较大时,基于Polar码的BICM系统较基于Polar码的无编码调制系统最大节省0.8 d B的比特信噪比.当信道编码码长为1 024、码率为0.5时,在中高比特信噪比区域上,基于Polar码的BICM系统可比基于LDPC码的BICM系统获得至少2 d B的比特信噪比增益.展开更多
结构化低密度奇偶校验码可通过基矩阵和扩展因子描述,具有较低的编译码复杂度和优异的译码性能。相比卫星导航系统IS-GPS-800协议中的非规则LDPC码,在校验位采用双对角和"a-0-a"连接关系的结构化LDPC码,同样可以达到线性复杂...结构化低密度奇偶校验码可通过基矩阵和扩展因子描述,具有较低的编译码复杂度和优异的译码性能。相比卫星导航系统IS-GPS-800协议中的非规则LDPC码,在校验位采用双对角和"a-0-a"连接关系的结构化LDPC码,同样可以达到线性复杂度编码。除此以外,通过设置不同的扩展因子和修剪操作,结构化LDPC码可以灵活支持不同多种长度的自适应传输,其中修剪操作的打孔/截短图案可以通过外信息转移(Extrinsic Informa-tion Transfer Charts,EXIT)分析方法优化。结合圈长分布和外信息度数谱联合优化设计方法,提出单个基矩阵的编码方案,通过配置不同的扩展因子和修剪方案,实现多种传输码长配置。译码仿真结果显示经过优化打孔/截短图案修剪的结构化LDPC码的译码性能要略优于IS-GPS-800协议中的非规则LDPC码。展开更多
基金The authors would like to thank the chair of Prince Faisal binMishaal Al Saud for Artificial Intelligent research for funding this research work through the project number QU-CPFAI-2-7-4Also would like to extend their appreciation to the Deputyship for Research&Innovation,Ministry of Education,and the Deanship of Scientific Research,Qassim University,for their support of this research.
文摘Bloom filter(BF)is a space-and-time efficient probabilistic technique that helps answermembership queries.However,BF faces several issues.The problems with traditional BF are generally two.Firstly,a large number of false positives can return wrong content when the data is queried.Secondly,the large size of BF is a bottleneck in the speed of querying and thus uses large memory.In order to solve the above two issues,in this article,we propose the check bits concept.From the implementation perspective,in the check bits approach,before saving the content value in the BF,we obtain the binary representation of the content value.Then,we take some bits of the content value,we call these the check bits.These bits are stored in a separate array such that they point to the same location as the BF.Finally,the content value(data)is stored in the BF based on the hash function values.Before retrieval of data from BF,the reverse process of the steps ensures that even if the same hash functions output has been generated for the content,the check bits make sure that the retrieval does not depend on the hash output alone.This thus helps in the reduction of false positives.In the experimental evaluation,we are able to reduce more than 50%of false positives.In our proposed approach,the false positives can still occur,however,false positives can only occur if the hash functions and check bits generate the same value for a particular content.The chances of such scenarios are less,therefore,we get a reduction of approximately more than 50%false positives in all cases.We believe that the proposed approach adds to the state of the art and opens new directions as such.
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.
文摘以信息节点的幅度和作为校验方程的可靠度信息,提出两种简单高效的低密度奇偶效验(low density parity check,LDPC)码的加权比特翻转(weighted bit flipping,WBF)译码算法。仿真结果表明,在加性高斯白噪声信道下,误比特率为10-5时,相比于传统的WBF和改进型WBF(modified WBF,MWBF)算法,提出的一种算法可分别获得约1.65dB和1.31dB的增益。同时,平均迭代次数也大大降低。
文摘为了研究Polar码在编码调制(CM)系统中的性能,提出了一种基于Polar码的比特交织编码调制(BICM)系统.分析了高斯白噪声(AWGN)信道中不同调制方式对系统误比特率(BER)性能的影响,并将所提系统的BER性能与基于低密度奇偶校验(LDPC)码的BICM系统性能进行了对比.仿真结果表明,在QPSK调制下,基于Polar码的BICM系统与基于Polar码的无编码调制系统的BER曲线几乎完全重合;而在16QAM调制下,当码长较大时,基于Polar码的BICM系统较基于Polar码的无编码调制系统最大节省0.8 d B的比特信噪比.当信道编码码长为1 024、码率为0.5时,在中高比特信噪比区域上,基于Polar码的BICM系统可比基于LDPC码的BICM系统获得至少2 d B的比特信噪比增益.
文摘结构化低密度奇偶校验码可通过基矩阵和扩展因子描述,具有较低的编译码复杂度和优异的译码性能。相比卫星导航系统IS-GPS-800协议中的非规则LDPC码,在校验位采用双对角和"a-0-a"连接关系的结构化LDPC码,同样可以达到线性复杂度编码。除此以外,通过设置不同的扩展因子和修剪操作,结构化LDPC码可以灵活支持不同多种长度的自适应传输,其中修剪操作的打孔/截短图案可以通过外信息转移(Extrinsic Informa-tion Transfer Charts,EXIT)分析方法优化。结合圈长分布和外信息度数谱联合优化设计方法,提出单个基矩阵的编码方案,通过配置不同的扩展因子和修剪方案,实现多种传输码长配置。译码仿真结果显示经过优化打孔/截短图案修剪的结构化LDPC码的译码性能要略优于IS-GPS-800协议中的非规则LDPC码。
