In this paper, we propose a new differential space-time-frequency （DSTF） modulation for MIMOOFDM system with four transmit-antennas and arbitrary receive-antennas, which can improve the transmission rate since it ca...In this paper, we propose a new differential space-time-frequency （DSTF） modulation for MIMOOFDM system with four transmit-antennas and arbitrary receive-antennas, which can improve the transmission rate since it can adopt high order quadrature amplitude modulation （QAM） modulation. Our proposed DSTF scheme embeds some full diversity full rate （FDFR） quasi-orthogonal space-time codes （QOSTBC） with QAM modulation into the frequency intervals and adopts the differential modulation in both time and frequency domains. The simulation results demonstrate that the proposed DSTF scheme can improve transmission rate greatly. Compared with the conventional differential unitary space-time modulation （DUSTM）, it can get better transmission performance in high transmission rate for MIMO-OFDM system.展开更多
Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting c...Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting code in this paper to investigate the improvements against partial-band jamming over AWGN channel. The performance of Fountain coded DFH is theoretically analyzed and numerically simulated. The total frequency of hopping in the simulation is 16, and results show that, on one hand, when exact jamming state information （JSI） is available, and the number of jamming frequency is n= 16, the bit error rate （BER） of 10~3 is achieved with the signal to interference ratio （SIR） approximately 7.5 dB over AWGN channel, and the performance improves about 1-1.5dB compared with the no-coded system. When the number of jamming frequency is n=2, the performance increases 15-17dB. On the other hand, when JSI is unavailable, a joint JSI estimation and decoding algorithm is proposed. The BER of 10 3 is achieved with jamming-frequency n 16, SIR=8dB and signal noise ratio （SNR） 10dB over AWGN channel. It＇s proved that this algorithm provides robust anti-jamming pertbrmance even without JSI. The anti-jamming performance of Fountain coded DFH systems is obviously superior to no-coded DFH systems.展开更多
基于球谐函数,实现区域电离层建模,并对区域差分码偏差(differential code bias,DCB)与总电子含量(total electron content,TEC)进行解算。对于格网处垂直总电子含量(vertical total electron content,VTEC)出现的异常值,提出一种序列...基于球谐函数,实现区域电离层建模,并对区域差分码偏差(differential code bias,DCB)与总电子含量(total electron content,TEC)进行解算。对于格网处垂直总电子含量(vertical total electron content,VTEC)出现的异常值,提出一种序列无约束最小化技术(sequential unconstrained minimization technique,SUMT)修正法进行修正,利用国际全球导航卫星系统服务(International GNSS Service,IGS)网络的6个测站双频观测数据,建立了电离层VTEC区域模型,并估算了31天的卫星频间DCB,将估算值与电离层分析中心中国科学院(Chinese Academy of Sciences,CAS)发布的产品进行对比分析,结果显示:所有的卫星差值都在0.42 ns以内,其中87.5%的卫星差值在0.4 ns以内,78.1%的卫星差值在0.2 ns以内,频间DCB的平均偏差基本小于0.4 ns。此外,估算的全球定位系统(global positioning system,GPS)卫星DCB序列的标准差(standard deviation,STD)值小于0.1 ns。建立了经纬度范围为5°E~25°E、40°N~60°N的电离层区域模型,将VTEC建模结果与CAS发布的全球电离层地图(global ionospheric map,GIM)产品做差比较,结果显示整体时间点的差值均处于4 TECU以内,且超过90%的区域差值在2 TECU以内,表明估算的结果与CAS产品具有良好的一致性。展开更多
This paper proposes a high-throughput short reference differential chaos shift keying cooperative communication system with the aid of code index modulation,referred to as CIM-SR-DCSK-CC system.In the proposed CIM-SR-...This paper proposes a high-throughput short reference differential chaos shift keying cooperative communication system with the aid of code index modulation,referred to as CIM-SR-DCSK-CC system.In the proposed CIM-SR-DCSK-CC system,the source transmits information bits to both the relay and destination in the first time slot,while the relay not only forwards the source information bits but also sends new information bits to the destination in the second time slot.To be specific,the relay employs an N-order Walsh code to carry additional log_(2)N information bits,which are superimposed onto the SRDCSK signal carrying the decoded source information bits.Subsequently,the superimposed signal carrying both the source and relay information bits is transmitted to the destination.Moreover,the theoretical bit error rate(BER)expressions of the proposed CIMSR-DCSK-CC system are derived over additive white Gaussian noise(AWGN)and multipath Rayleigh fading channels.Compared with the conventional DCSKCC system and SR-DCSK-CC system,the proposed CIM-SR-DCSK-CC system can significantly improve the throughput without deteriorating any BER performance.As a consequence,the proposed system is very promising for the applications of the 6G-enabled lowpower and high-rate communication.展开更多
We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characterist...We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.展开更多
通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务...通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务的UPPP模型,分析了DCB对UPPP定位、收敛时间、对流层、钟差及斜向电离层解算的影响。在非组合模型下,采用北斗三号PPP-B2b实时精密单点定位(Real-Time Precise Point Positioning B2b,RTPPP-B2b)软件对接收机实测数据进行实验分析。实验结果表明:载波与伪距观测值权比为103∶1时,DCB对定位精度和收敛时间影响均较小,载波与伪距观测值权比为102∶1时,无DCB校正的UPPP定位误差收敛时间会变长;DCB对解算对流层天顶总延迟的影响可以忽略,对接收机钟差影响在亚纳秒级别;在使用UPPP提取斜向电离层过程中,DCB主要影响斜向电离层的计算精度。展开更多
基金This work was supported in part by the National Natural Science Foundation of China under grant No. 60572117the Natural Science Foundation of Hubei Province under grant No. 2005ABA244.
文摘In this paper, we propose a new differential space-time-frequency （DSTF） modulation for MIMOOFDM system with four transmit-antennas and arbitrary receive-antennas, which can improve the transmission rate since it can adopt high order quadrature amplitude modulation （QAM） modulation. Our proposed DSTF scheme embeds some full diversity full rate （FDFR） quasi-orthogonal space-time codes （QOSTBC） with QAM modulation into the frequency intervals and adopts the differential modulation in both time and frequency domains. The simulation results demonstrate that the proposed DSTF scheme can improve transmission rate greatly. Compared with the conventional differential unitary space-time modulation （DUSTM）, it can get better transmission performance in high transmission rate for MIMO-OFDM system.
基金the National Natural Science Foundation of China under Grant 61371125
文摘Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting code in this paper to investigate the improvements against partial-band jamming over AWGN channel. The performance of Fountain coded DFH is theoretically analyzed and numerically simulated. The total frequency of hopping in the simulation is 16, and results show that, on one hand, when exact jamming state information （JSI） is available, and the number of jamming frequency is n= 16, the bit error rate （BER） of 10~3 is achieved with the signal to interference ratio （SIR） approximately 7.5 dB over AWGN channel, and the performance improves about 1-1.5dB compared with the no-coded system. When the number of jamming frequency is n=2, the performance increases 15-17dB. On the other hand, when JSI is unavailable, a joint JSI estimation and decoding algorithm is proposed. The BER of 10 3 is achieved with jamming-frequency n 16, SIR=8dB and signal noise ratio （SNR） 10dB over AWGN channel. It＇s proved that this algorithm provides robust anti-jamming pertbrmance even without JSI. The anti-jamming performance of Fountain coded DFH systems is obviously superior to no-coded DFH systems.
基金supported in part by the NSF of China under Grant 62322106,62071131 and 62171135the Guangdong Basic and Applied Basic Research Foundation under Grant 2022B1515020086+2 种基金the NSF of Guangdong Province under Grant 2019A1515011465the International Collaborative Research Program of Guangdong Science and Technology Department under Grant 2022A0505050070the Industrial R&D Project of Haoyang Electronic Co.,Ltd.under Grant 2022440002001494.
文摘This paper proposes a high-throughput short reference differential chaos shift keying cooperative communication system with the aid of code index modulation,referred to as CIM-SR-DCSK-CC system.In the proposed CIM-SR-DCSK-CC system,the source transmits information bits to both the relay and destination in the first time slot,while the relay not only forwards the source information bits but also sends new information bits to the destination in the second time slot.To be specific,the relay employs an N-order Walsh code to carry additional log_(2)N information bits,which are superimposed onto the SRDCSK signal carrying the decoded source information bits.Subsequently,the superimposed signal carrying both the source and relay information bits is transmitted to the destination.Moreover,the theoretical bit error rate(BER)expressions of the proposed CIMSR-DCSK-CC system are derived over additive white Gaussian noise(AWGN)and multipath Rayleigh fading channels.Compared with the conventional DCSKCC system and SR-DCSK-CC system,the proposed CIM-SR-DCSK-CC system can significantly improve the throughput without deteriorating any BER performance.As a consequence,the proposed system is very promising for the applications of the 6G-enabled lowpower and high-rate communication.
文摘We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.
文摘通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务的UPPP模型,分析了DCB对UPPP定位、收敛时间、对流层、钟差及斜向电离层解算的影响。在非组合模型下,采用北斗三号PPP-B2b实时精密单点定位(Real-Time Precise Point Positioning B2b,RTPPP-B2b)软件对接收机实测数据进行实验分析。实验结果表明:载波与伪距观测值权比为103∶1时,DCB对定位精度和收敛时间影响均较小,载波与伪距观测值权比为102∶1时,无DCB校正的UPPP定位误差收敛时间会变长;DCB对解算对流层天顶总延迟的影响可以忽略,对接收机钟差影响在亚纳秒级别;在使用UPPP提取斜向电离层过程中,DCB主要影响斜向电离层的计算精度。
