针对基于路径分裂策略辅助极化码串行抵消列表(Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List,PSS-SS-SCL)译码算法性能的不足,提出了一种利用增强型奇偶校验码改进PSSSS-SCL译码算法...针对基于路径分裂策略辅助极化码串行抵消列表(Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List,PSS-SS-SCL)译码算法性能的不足,提出了一种利用增强型奇偶校验码改进PSSSS-SCL译码算法的EPC-MS-SCL(Enhanced Parity Check and Monte Carlo Segment aided Successive Cancellation List)译码算法.该算法在极化码编码阶段对信息序列做分段处理,在每段末尾添加增强型奇偶校验码,译码器仅在译码搜索集内元素时进行路径分裂,其余元素直接执行硬判决译码,并在译码完一段序列后立即对该段进行校验,仅保留通过校验的路径,从而减少了错误路径对正确路径的竞争,使正确路径保留到译码结束的概率增加,改善了译码性能,同时减少了译码列表数,使得译码复杂度更低.仿真结果表明,与PSS-SS-SCL译码算法相比较,所提出算法能在一定程度上改善其性能增益且具有更低的译码复杂度.展开更多
A new concatenated code of RS(255,239)+BCH(2 040,1 930) code to be suitable for WDM optical transmission systems is proposed. The simulation results show that this new concatenated code, compared with the RS(255,239)+...A new concatenated code of RS(255,239)+BCH(2 040,1 930) code to be suitable for WDM optical transmission systems is proposed. The simulation results show that this new concatenated code, compared with the RS(255,239)+CSOC(k0/n0=6/7, J=8) code in ITU-T G.75.1, has a lower redundancy and better error-correction performance, furthermore, its net coding gain(NCG) is respectively 0.46 dB, 0.43 dB more than that of RS(255,239)+CSOC(k0/n0 =6/7, J=8) code and BCH(3 860,3 824)+BCH(2 040,1 930) code in ITU-T G.75.1 at the third iteration for the bit error rate(BER) of 10-12. Therefore, the new super forward error correction(Super-FEC) concatenated code can be better used in ultra long-haul, ultra large-capacity and ultra high-speed WDM optical communication systems.展开更多
目的了解北京市通州区319例尘肺病患者的健康寿命损失年(years lived with disability,YLD)情况,为该地区今后的尘肺病防治工作提供一定的数据支持。方法以截止到2021年7月31日通过“职业病及健康危害因素监测信息系统”平台获得的北京...目的了解北京市通州区319例尘肺病患者的健康寿命损失年(years lived with disability,YLD)情况,为该地区今后的尘肺病防治工作提供一定的数据支持。方法以截止到2021年7月31日通过“职业病及健康危害因素监测信息系统”平台获得的北京市通州区319例尘肺病个案资料作为分析对象,描述尘肺病患者的一般情况、YLD情况,分析YLD在不同分层情况下的数据对比情况。结果319例尘肺病患者的年龄分布在30~86岁,平均(52.41±11.75)岁。319例尘肺病患者的YLD合计为2704.66年,M(P_(25),P_(75))为8.41(2.03,15.62)年。<40岁年龄段患者的YLD高于其他年龄段患者(H=124.553,χ^(2)=23.112、18.212、17.257、40.357,均P<0.05),尘肺Ⅰ期患者的YLD高于其他分期的患者(H=88.634,χ^(2)=25.331、38.112,均P<0.05),石棉肺患者的YLD高于其他尘肺类型患者(H=136.520,χ^(2)=24.368、37.258、24.125,均P<0.05),伤残等级数值较高患者的YLD高于其他伤残等级数值较低的患者(H=87.632,χ^(2)=32.358、31.256、29.994,均P<0.05),私有经济企业患者的YLD高于其他经济类型的患者(H=99.657,χ^(2)=39.945、42.309,均P<0.05),微型以及小型企业患者的YLD高于其他企业规模的患者(H=162.58,χ^(2)=77.425、61.258、80.354、48.369、62.007、72.358,均P<0.05),不同居住街道尘肺病患者的YLD数据比较,差异无统计学意义(H=1.023,P>0.05)。结论尘肺病会给患者个体带来较为沉重的健康寿命损失,尤其对于<50岁的职业人群的健康监测需要重度关注。另外,需要有关部门对微小型私有企业进行严格的监管,降低尘肺病的发病率,推迟发病时间,有效减轻尘肺病的健康负担。展开更多
Aiming at the problem that quasi-cyclic low density parity check(QC-LDPC) codes may have the error floor in the high signal to noise ratio(SNR) region, a new construction method of the QC-LDPC codes with the low error...Aiming at the problem that quasi-cyclic low density parity check(QC-LDPC) codes may have the error floor in the high signal to noise ratio(SNR) region, a new construction method of the QC-LDPC codes with the low error floor is proposed. The basic matrix of the method is based on the progressive edge growth(PEG) algorithm and the improved eliminate elementary trapping sets(EETS) algorithm so as to eliminate the elementary trapping sets in the basic matrix,then the Zig-Zag method is used to construct the cyclic shift matrix which is used to extend the basic matrix in order to construct the parity check matrix. The method not only can improve the error floor in the high SNR region, but also can flexibly design the code length and code rate. The simulation results show that at the bit error rate of 10-6, the PEG-trapping-Zig-Zag(PTZZ)-QC-LDPC(3024,1512) codes with the code rate of 0.5, compared with the PEG-Zig-Zag(PZZ)-QC-LDPC(3024,1512) codes and the PEG-QC-LDPC(3024,1512) codes, can respectively improve the net coding gain of 0.1 dB and 0.16 dB. The difference among the bit error rate performance curves will become better with the increase of the SNR. In addition, the PTZZ-QC-LDPC(3024,1512) codes have no error floor above the SNR of 2.2 dB.展开更多
A novel phase noise(PN)compensation algorithm based on the decision feedback(DF)algorithm and the linear combination self cancellation(LCSC)algorithm is proposed to improve the system performance degradation caused by...A novel phase noise(PN)compensation algorithm based on the decision feedback(DF)algorithm and the linear combination self cancellation(LCSC)algorithm is proposed to improve the system performance degradation caused by laser linewidth in coherent optical orthogonal frequency division multiplexing(CO-OFDM)systems.In this proposed LCSC-DF algorithm,the LCSC algorithm is used to precode the subcarrier information at the transmitter and decode the demodulation information and inter-carrier interference(ICI)related information at the receiver.And then the pilot information is used to obtain the final compensation signal by the improved DF algorithm.The simulation results show that the PN compensation performance of the proposed LCSC-DF algorithm is better than that of the DF algorithm.Furthermore,with the increase of the signal to noise ratio(SNR),its bit error rate(BER)performance approaches to that of the SC-DF algorithm at the larger PN linewidth.The subcarriers utilization ratio of the proposed algorithm is higher than that of the SC-DF algorithm.As a result,the proposed algorithm can effectively improve the performance of the system.展开更多
文摘针对基于路径分裂策略辅助极化码串行抵消列表(Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List,PSS-SS-SCL)译码算法性能的不足,提出了一种利用增强型奇偶校验码改进PSSSS-SCL译码算法的EPC-MS-SCL(Enhanced Parity Check and Monte Carlo Segment aided Successive Cancellation List)译码算法.该算法在极化码编码阶段对信息序列做分段处理,在每段末尾添加增强型奇偶校验码,译码器仅在译码搜索集内元素时进行路径分裂,其余元素直接执行硬判决译码,并在译码完一段序列后立即对该段进行校验,仅保留通过校验的路径,从而减少了错误路径对正确路径的竞争,使正确路径保留到译码结束的概率增加,改善了译码性能,同时减少了译码列表数,使得译码复杂度更低.仿真结果表明,与PSS-SS-SCL译码算法相比较,所提出算法能在一定程度上改善其性能增益且具有更低的译码复杂度.
基金National High Technology Development Program(863) of China (2005AA123730) Natural Science Foundation of Chongqing University of Posts & Telecommunications(A2006 -53)
文摘A new concatenated code of RS(255,239)+BCH(2 040,1 930) code to be suitable for WDM optical transmission systems is proposed. The simulation results show that this new concatenated code, compared with the RS(255,239)+CSOC(k0/n0=6/7, J=8) code in ITU-T G.75.1, has a lower redundancy and better error-correction performance, furthermore, its net coding gain(NCG) is respectively 0.46 dB, 0.43 dB more than that of RS(255,239)+CSOC(k0/n0 =6/7, J=8) code and BCH(3 860,3 824)+BCH(2 040,1 930) code in ITU-T G.75.1 at the third iteration for the bit error rate(BER) of 10-12. Therefore, the new super forward error correction(Super-FEC) concatenated code can be better used in ultra long-haul, ultra large-capacity and ultra high-speed WDM optical communication systems.
文摘目的了解北京市通州区319例尘肺病患者的健康寿命损失年(years lived with disability,YLD)情况,为该地区今后的尘肺病防治工作提供一定的数据支持。方法以截止到2021年7月31日通过“职业病及健康危害因素监测信息系统”平台获得的北京市通州区319例尘肺病个案资料作为分析对象,描述尘肺病患者的一般情况、YLD情况,分析YLD在不同分层情况下的数据对比情况。结果319例尘肺病患者的年龄分布在30~86岁,平均(52.41±11.75)岁。319例尘肺病患者的YLD合计为2704.66年,M(P_(25),P_(75))为8.41(2.03,15.62)年。<40岁年龄段患者的YLD高于其他年龄段患者(H=124.553,χ^(2)=23.112、18.212、17.257、40.357,均P<0.05),尘肺Ⅰ期患者的YLD高于其他分期的患者(H=88.634,χ^(2)=25.331、38.112,均P<0.05),石棉肺患者的YLD高于其他尘肺类型患者(H=136.520,χ^(2)=24.368、37.258、24.125,均P<0.05),伤残等级数值较高患者的YLD高于其他伤残等级数值较低的患者(H=87.632,χ^(2)=32.358、31.256、29.994,均P<0.05),私有经济企业患者的YLD高于其他经济类型的患者(H=99.657,χ^(2)=39.945、42.309,均P<0.05),微型以及小型企业患者的YLD高于其他企业规模的患者(H=162.58,χ^(2)=77.425、61.258、80.354、48.369、62.007、72.358,均P<0.05),不同居住街道尘肺病患者的YLD数据比较,差异无统计学意义(H=1.023,P>0.05)。结论尘肺病会给患者个体带来较为沉重的健康寿命损失,尤其对于<50岁的职业人群的健康监测需要重度关注。另外,需要有关部门对微小型私有企业进行严格的监管,降低尘肺病的发病率,推迟发病时间,有效减轻尘肺病的健康负担。
基金financially supported by the National Natural Science Foundation of China(No.61471075)the Program for Postgraduate Science Research and Innovation of Chongqing University of Posts and Telecommunications(Chongqing Municipal Education Commission)(No.CYS17241)the Undergraduate Science Research Training Project for Chongqing University of Posts and Telecommunication(No.201901013)
文摘Aiming at the problem that quasi-cyclic low density parity check(QC-LDPC) codes may have the error floor in the high signal to noise ratio(SNR) region, a new construction method of the QC-LDPC codes with the low error floor is proposed. The basic matrix of the method is based on the progressive edge growth(PEG) algorithm and the improved eliminate elementary trapping sets(EETS) algorithm so as to eliminate the elementary trapping sets in the basic matrix,then the Zig-Zag method is used to construct the cyclic shift matrix which is used to extend the basic matrix in order to construct the parity check matrix. The method not only can improve the error floor in the high SNR region, but also can flexibly design the code length and code rate. The simulation results show that at the bit error rate of 10-6, the PEG-trapping-Zig-Zag(PTZZ)-QC-LDPC(3024,1512) codes with the code rate of 0.5, compared with the PEG-Zig-Zag(PZZ)-QC-LDPC(3024,1512) codes and the PEG-QC-LDPC(3024,1512) codes, can respectively improve the net coding gain of 0.1 dB and 0.16 dB. The difference among the bit error rate performance curves will become better with the increase of the SNR. In addition, the PTZZ-QC-LDPC(3024,1512) codes have no error floor above the SNR of 2.2 dB.
基金This work has been supported by the National Natural Science Foundation of China(Nos.61971079 and 61671091)the Natural Science Foundation of Chongqing Science and Technology Commission(No.csts2017jcyjAX0427).
文摘A novel phase noise(PN)compensation algorithm based on the decision feedback(DF)algorithm and the linear combination self cancellation(LCSC)algorithm is proposed to improve the system performance degradation caused by laser linewidth in coherent optical orthogonal frequency division multiplexing(CO-OFDM)systems.In this proposed LCSC-DF algorithm,the LCSC algorithm is used to precode the subcarrier information at the transmitter and decode the demodulation information and inter-carrier interference(ICI)related information at the receiver.And then the pilot information is used to obtain the final compensation signal by the improved DF algorithm.The simulation results show that the PN compensation performance of the proposed LCSC-DF algorithm is better than that of the DF algorithm.Furthermore,with the increase of the signal to noise ratio(SNR),its bit error rate(BER)performance approaches to that of the SC-DF algorithm at the larger PN linewidth.The subcarriers utilization ratio of the proposed algorithm is higher than that of the SC-DF algorithm.As a result,the proposed algorithm can effectively improve the performance of the system.