Through analyzing the theoretical spreading principle,it has been proved in this paper that the benefit of pseudo-orthogonal carrier interferometry(PO-CI)spreading code is not supported when complex signal modulation(...Through analyzing the theoretical spreading principle,it has been proved in this paper that the benefit of pseudo-orthogonal carrier interferometry(PO-CI)spreading code is not supported when complex signal modulation(e.g.,quadrature phase-shift keying(QPSK)and quadrature amplitude modulation(QAM))types are employed.On this basis,a novel and feasible structure for this problem is brought forward.Within the structure mentioned,instead of complex modulation patterns,pulse amplitude modulation(PAM)combined with PO-CI spreading code is utilized.This allows us to maintain the throughput increase of a multi-carrier code division multiple access(MC-CDMA)system with minimal loss in performance and no bandwidth expansion.展开更多
We propose a novel iteration-free blind phase noise estimation scheme for coherent optical orthogonal frequency division multiplexing （CO-OFDM） systems. In the new algorithm, the cost function is selected as the sim...We propose a novel iteration-free blind phase noise estimation scheme for coherent optical orthogonal frequency division multiplexing （CO-OFDM） systems. In the new algorithm, the cost function is selected as the similar expression with real and imaginary parts as that in the modified constant modulus algorithm, and the new cost function is derived under some assumptions, where it is infinitely approximated by the sine and cosine functions. By means of the analytical formula of the cost function, the initial coarse common phase error can be obtained with only some samples, where the algorithm avoids computational complexity of conventional blind phase noise compensation scheme. In CO-OFDM systems with high-order modulation format （32 quadrature amplitude modulation） and narrow linewidth lasers, it is proved by the simulation results that the nhase noise can be effectively compensated with the proposed blind estimation method.展开更多
针对高动态场景下多普勒频移问题和缺少定量分析,该文以研究正交调制的多普勒频移响应机理为基点,对多普勒频移对正交调制系统的影响进行了研究,从星座图判决区间的角度推导了多进制数字相位调制信号和多进制正交幅度调制信号在多普勒...针对高动态场景下多普勒频移问题和缺少定量分析,该文以研究正交调制的多普勒频移响应机理为基点,对多普勒频移对正交调制系统的影响进行了研究,从星座图判决区间的角度推导了多进制数字相位调制信号和多进制正交幅度调制信号在多普勒频移下的误符号率公式。理论分析和实验结果表明:多普勒频移对正交调制的影响是星座的旋转,误符号率公式推导结果与实际误符号率基本相同,系统的性能随着调制指数和运动速度的增加而下降。在信噪比为20 d B时,多进制数字相位调制信号的抗多普勒频移能力要强于多进制正交幅度调制信号。展开更多
针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在...针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在载波频偏情况下OFDM/OQAM接收信号的二阶循环平稳特性,在此基础上,提出一种OFDM/OQAM系统载波频率偏差的盲估计算法。理论分析和仿真结果表明由该方法构造的估计器不仅能够有效地抵抗双选信道引起的衰落而且具有很好的抗噪性能,从而可以实现对载波频偏的稳健估计。展开更多
广义空频索引调制(generalized space and frequency index modulation,GSFIM)技术的提出显示了其相比传统多输入多输出正交频分复用技术更优的系统性能。然而,GSFIM有着较复杂的系统结构以及高复杂度的检测器。讨论一种特殊形式的空频...广义空频索引调制(generalized space and frequency index modulation,GSFIM)技术的提出显示了其相比传统多输入多输出正交频分复用技术更优的系统性能。然而,GSFIM有着较复杂的系统结构以及高复杂度的检测器。讨论一种特殊形式的空频索引调制技术,即基于频率正交幅度调制(frequency and quadrature amplitude modulation,FQAM)/频相移键控(frequency and phase shift keying,FPSK)的空间调制(spatial modulation,SM)技术,其大大简化了系统结构。为了进一步提升该系统的频谱效率,提出了结合非正交子载波的FQAM/FPSK-SM。仿真结果表明,在不同的参数配置下,通过调整压缩系数,非正交FQAM/FPSK-SM系统不仅能够带来频谱效率的提升,而且能够在发送速率相同的前提下达到与正交系统基本相同的性能,提高了系统的单位带宽吞吐量。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.60496312).
文摘Through analyzing the theoretical spreading principle,it has been proved in this paper that the benefit of pseudo-orthogonal carrier interferometry(PO-CI)spreading code is not supported when complex signal modulation(e.g.,quadrature phase-shift keying(QPSK)and quadrature amplitude modulation(QAM))types are employed.On this basis,a novel and feasible structure for this problem is brought forward.Within the structure mentioned,instead of complex modulation patterns,pulse amplitude modulation(PAM)combined with PO-CI spreading code is utilized.This allows us to maintain the throughput increase of a multi-carrier code division multiple access(MC-CDMA)system with minimal loss in performance and no bandwidth expansion.
基金supported in part by the China Postdoctoral Science Foundation(No.2013M540361)the National Natural Science Foundation of China(Nos.60907032 and 61275124)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY13F010011)the Zhejiang Youth Science Fund(No.LQ13F050005)
文摘We propose a novel iteration-free blind phase noise estimation scheme for coherent optical orthogonal frequency division multiplexing （CO-OFDM） systems. In the new algorithm, the cost function is selected as the similar expression with real and imaginary parts as that in the modified constant modulus algorithm, and the new cost function is derived under some assumptions, where it is infinitely approximated by the sine and cosine functions. By means of the analytical formula of the cost function, the initial coarse common phase error can be obtained with only some samples, where the algorithm avoids computational complexity of conventional blind phase noise compensation scheme. In CO-OFDM systems with high-order modulation format （32 quadrature amplitude modulation） and narrow linewidth lasers, it is proved by the simulation results that the nhase noise can be effectively compensated with the proposed blind estimation method.
文摘针对高动态场景下多普勒频移问题和缺少定量分析,该文以研究正交调制的多普勒频移响应机理为基点,对多普勒频移对正交调制系统的影响进行了研究,从星座图判决区间的角度推导了多进制数字相位调制信号和多进制正交幅度调制信号在多普勒频移下的误符号率公式。理论分析和实验结果表明:多普勒频移对正交调制的影响是星座的旋转,误符号率公式推导结果与实际误符号率基本相同,系统的性能随着调制指数和运动速度的增加而下降。在信噪比为20 d B时,多进制数字相位调制信号的抗多普勒频移能力要强于多进制正交幅度调制信号。
文摘针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在载波频偏情况下OFDM/OQAM接收信号的二阶循环平稳特性,在此基础上,提出一种OFDM/OQAM系统载波频率偏差的盲估计算法。理论分析和仿真结果表明由该方法构造的估计器不仅能够有效地抵抗双选信道引起的衰落而且具有很好的抗噪性能,从而可以实现对载波频偏的稳健估计。
文摘广义空频索引调制(generalized space and frequency index modulation,GSFIM)技术的提出显示了其相比传统多输入多输出正交频分复用技术更优的系统性能。然而,GSFIM有着较复杂的系统结构以及高复杂度的检测器。讨论一种特殊形式的空频索引调制技术,即基于频率正交幅度调制(frequency and quadrature amplitude modulation,FQAM)/频相移键控(frequency and phase shift keying,FPSK)的空间调制(spatial modulation,SM)技术,其大大简化了系统结构。为了进一步提升该系统的频谱效率,提出了结合非正交子载波的FQAM/FPSK-SM。仿真结果表明,在不同的参数配置下,通过调整压缩系数,非正交FQAM/FPSK-SM系统不仅能够带来频谱效率的提升,而且能够在发送速率相同的前提下达到与正交系统基本相同的性能,提高了系统的单位带宽吞吐量。
