频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽...频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽。用于同步的训练序列还可用于信道估计和均衡,这将提高系统的数据传输效率。 此算法同步精度达到了Schmidl提出的Cramer-Rao bound,有效性在AWGN和Rayleigh多径信道下得到了验证。展开更多
为了解决MIMO-OFDM系统的多时延问题,提出了一种改进的基于恒包络零自相关(Constant Amplitude Zero Auto Correlation,CAZAC)序列的MIMO-OFDM时间同步算法。该算法利用不同根值的CAZAC序列,区分不同天线间的时延,利用CAZAC序列良好的...为了解决MIMO-OFDM系统的多时延问题,提出了一种改进的基于恒包络零自相关(Constant Amplitude Zero Auto Correlation,CAZAC)序列的MIMO-OFDM时间同步算法。该算法利用不同根值的CAZAC序列,区分不同天线间的时延,利用CAZAC序列良好的自相关性,得到各天线间的准确定时位置。仿真结果表明,该算法性能良好,能够准确估计出MIMO-OFDM系统各个天线的时延。展开更多
利用CAZAC(Constant Amplitude Zero Auto Correlation)序列良好的特性,通过改变IEEE 802.11a系统标准前导结构,重新设计了用于分组检测的短训练序列,并提出新的分组检测算法。新算法避免了分组检测训练序列与结构中的其他重复短训练之...利用CAZAC(Constant Amplitude Zero Auto Correlation)序列良好的特性,通过改变IEEE 802.11a系统标准前导结构,重新设计了用于分组检测的短训练序列,并提出新的分组检测算法。新算法避免了分组检测训练序列与结构中的其他重复短训练之间的相关干扰,同时增加了用于粗频率同步的短训练序列的个数,因此增加了粗频率同步的准确度,但不改变整个前导符号序列的个数,也没有增加算法的复杂度。在突发模式下,使用瑞利时延多径衰减信道进行仿真,与传统方法比较能得到4dB的增益。展开更多
提出了一种基于CAZAC(Constant Amplitude Zero Auto Correlation)的改进帧同步检测方案。首先,利用CAZAC序列作为短训练序列来改变IEEE802.11a系统标准前导结构,并增加用于粗频偏估计的短训练序列个数;其次,在使用延时相关帧检测的基础...提出了一种基于CAZAC(Constant Amplitude Zero Auto Correlation)的改进帧同步检测方案。首先,利用CAZAC序列作为短训练序列来改变IEEE802.11a系统标准前导结构,并增加用于粗频偏估计的短训练序列个数;其次,在使用延时相关帧检测的基础上,结合短训练序列的互相关信息共同完成帧同步检测。由于CAZAC序列良好的自身特性以及互相关信息的辅助,使得帧同步检测更加准确,粗频偏估计的性能也有所提高,大频偏下仍得到稳定的性能。仿真结果显示,在多径时延为100ns,频偏为200kHz时,与传统方法比较能得到约2dB的增益。展开更多
针对水声信道时变、频变、强噪声及可用频带资源有限的特点,提出一种水下多用户通信方法。通过分析研究恒包络零自相关(Const Amplitude Zero Auto-Corelation,CAZAC)序列信号、双曲调频(Hyperbolic Frequency Modulated,HFM)信号在水...针对水声信道时变、频变、强噪声及可用频带资源有限的特点,提出一种水下多用户通信方法。通过分析研究恒包络零自相关(Const Amplitude Zero Auto-Corelation,CAZAC)序列信号、双曲调频(Hyperbolic Frequency Modulated,HFM)信号在水声信道下的扩展特性,设计一种采用CAZAC序列调制HFM信号的多用户水声通信方法。该方法不需前导信号,在同一频带内可实现对多个水声通信用户的识别及通信,且接收端通过相关检测处理具有优良的抗多途、抗多普勒频移特性。对8个用户在典型的水声信道多途模型下进行了仿真,结果表明该方法在水下平台相对运动3 m·s^(-1)、信噪比5 dB的条件下能够实现对多个用户的可靠水声通信。展开更多
To meet the requirements of Occupied Channel Bandwidth(OCB)of unlicensed spectrum,in NR-based Access to Unlicensed Spectrum(NR-U)of 5G New Radio(NR)system,the channels of PRACH and PUCCH have to employ some frequency ...To meet the requirements of Occupied Channel Bandwidth(OCB)of unlicensed spectrum,in NR-based Access to Unlicensed Spectrum(NR-U)of 5G New Radio(NR)system,the channels of PRACH and PUCCH have to employ some frequency domain sequence repetition schemes.These repeti-tion schemes cause serious Cubic Metric(CM)prob-lems for these channels,although these two types of channels are composed of Constant Amplitude Zero Auto-correlation(CAZAC)sequences.Considering the properties of CAZAC sequences,which are used for PRACH and PUCCH(refer to PUCCH format 0 and format 1)in 5G NR system,in this paper,we pro-pose some new schemes of CM reduction for these two channels taking into account the design princi-ples to ensure the sequence performance of the auto-correlation and cross-correlation.Then the recom-mended CM reduction schemes are evaluated and the optimized parameters are further provided considering both CM performance and the complexity.展开更多
In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlatio...In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.展开更多
A novel symbol timing synchronization algorithm based on constant amplitude zero auto correlation(CAZAC) sequences is proposed for coherent optical orthogonal frequency division multiplexing(CO-OFDM) systems. The trai...A novel symbol timing synchronization algorithm based on constant amplitude zero auto correlation(CAZAC) sequences is proposed for coherent optical orthogonal frequency division multiplexing(CO-OFDM) systems. The training symbol of the proposed algorithm is comprised of four different parts, utilizing even symmetry property of each part to accomplish timing synchronization. The performance of the proposed algorithm is demonstrated by means of simulations in OFDM and CO-OFDM systems. The proposed algorithm is shown to eliminate the timing sidelobes of Park's algorithm and has a more accurate timing estimation. In the condition of chromatic dispersion(CD), the timing metric of the proposed method still maintains its peak value at the correct timing point, while the values are almost 0 at all the other positions. Meanwhile, the timing mean square error(MSE) of the proposed algorithm remains around 10^(-6).展开更多
文摘频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽。用于同步的训练序列还可用于信道估计和均衡,这将提高系统的数据传输效率。 此算法同步精度达到了Schmidl提出的Cramer-Rao bound,有效性在AWGN和Rayleigh多径信道下得到了验证。
文摘为了解决MIMO-OFDM系统的多时延问题,提出了一种改进的基于恒包络零自相关(Constant Amplitude Zero Auto Correlation,CAZAC)序列的MIMO-OFDM时间同步算法。该算法利用不同根值的CAZAC序列,区分不同天线间的时延,利用CAZAC序列良好的自相关性,得到各天线间的准确定时位置。仿真结果表明,该算法性能良好,能够准确估计出MIMO-OFDM系统各个天线的时延。
文摘利用CAZAC(Constant Amplitude Zero Auto Correlation)序列良好的特性,通过改变IEEE 802.11a系统标准前导结构,重新设计了用于分组检测的短训练序列,并提出新的分组检测算法。新算法避免了分组检测训练序列与结构中的其他重复短训练之间的相关干扰,同时增加了用于粗频率同步的短训练序列的个数,因此增加了粗频率同步的准确度,但不改变整个前导符号序列的个数,也没有增加算法的复杂度。在突发模式下,使用瑞利时延多径衰减信道进行仿真,与传统方法比较能得到4dB的增益。
文摘提出了一种基于CAZAC(Constant Amplitude Zero Auto Correlation)的改进帧同步检测方案。首先,利用CAZAC序列作为短训练序列来改变IEEE802.11a系统标准前导结构,并增加用于粗频偏估计的短训练序列个数;其次,在使用延时相关帧检测的基础上,结合短训练序列的互相关信息共同完成帧同步检测。由于CAZAC序列良好的自身特性以及互相关信息的辅助,使得帧同步检测更加准确,粗频偏估计的性能也有所提高,大频偏下仍得到稳定的性能。仿真结果显示,在多径时延为100ns,频偏为200kHz时,与传统方法比较能得到约2dB的增益。
文摘针对水声信道时变、频变、强噪声及可用频带资源有限的特点,提出一种水下多用户通信方法。通过分析研究恒包络零自相关(Const Amplitude Zero Auto-Corelation,CAZAC)序列信号、双曲调频(Hyperbolic Frequency Modulated,HFM)信号在水声信道下的扩展特性,设计一种采用CAZAC序列调制HFM信号的多用户水声通信方法。该方法不需前导信号,在同一频带内可实现对多个水声通信用户的识别及通信,且接收端通过相关检测处理具有优良的抗多途、抗多普勒频移特性。对8个用户在典型的水声信道多途模型下进行了仿真,结果表明该方法在水下平台相对运动3 m·s^(-1)、信噪比5 dB的条件下能够实现对多个用户的可靠水声通信。
文摘To meet the requirements of Occupied Channel Bandwidth(OCB)of unlicensed spectrum,in NR-based Access to Unlicensed Spectrum(NR-U)of 5G New Radio(NR)system,the channels of PRACH and PUCCH have to employ some frequency domain sequence repetition schemes.These repeti-tion schemes cause serious Cubic Metric(CM)prob-lems for these channels,although these two types of channels are composed of Constant Amplitude Zero Auto-correlation(CAZAC)sequences.Considering the properties of CAZAC sequences,which are used for PRACH and PUCCH(refer to PUCCH format 0 and format 1)in 5G NR system,in this paper,we pro-pose some new schemes of CM reduction for these two channels taking into account the design princi-ples to ensure the sequence performance of the auto-correlation and cross-correlation.Then the recom-mended CM reduction schemes are evaluated and the optimized parameters are further provided considering both CM performance and the complexity.
基金supported by the Scientific Research Foundation for the Doctor′s Degree,Beijing University of Technology(No.X0002012200903)the State Key Laboratory of Integrated Services Networks(Xidian University),China(No.ISN10-02)
文摘In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.
文摘A novel symbol timing synchronization algorithm based on constant amplitude zero auto correlation(CAZAC) sequences is proposed for coherent optical orthogonal frequency division multiplexing(CO-OFDM) systems. The training symbol of the proposed algorithm is comprised of four different parts, utilizing even symmetry property of each part to accomplish timing synchronization. The performance of the proposed algorithm is demonstrated by means of simulations in OFDM and CO-OFDM systems. The proposed algorithm is shown to eliminate the timing sidelobes of Park's algorithm and has a more accurate timing estimation. In the condition of chromatic dispersion(CD), the timing metric of the proposed method still maintains its peak value at the correct timing point, while the values are almost 0 at all the other positions. Meanwhile, the timing mean square error(MSE) of the proposed algorithm remains around 10^(-6).
