This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increas...This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increase the spectrum efficiency,an improved preamble structure without guard symbols is derived at first. On this basis, instead of deriving the log likelihood function of power spectral density, joint estimation of the symbol timing offset and carrier frequency offset based on the preamble proposed is formulated into a bivariate optimization problem. After that, an improved genetic algorithm is used to find its global optimum solution. Conclusions can be drawn from simulation results that the proposed method has advantages in the joint estimation of synchronization.展开更多
电力电子变换器通过功率与数据信息的复合调制,可使其在电能变换传输的同时进行数据信息的传输,从而实现能量信息一体化。该文以交错并联DC-DC变换器为研究对象,提出基于正交频分复用-多进制正交幅度调制(OFDM-MQAM)的能量信息一体化方...电力电子变换器通过功率与数据信息的复合调制,可使其在电能变换传输的同时进行数据信息的传输,从而实现能量信息一体化。该文以交错并联DC-DC变换器为研究对象,提出基于正交频分复用-多进制正交幅度调制(OFDM-MQAM)的能量信息一体化方法,并详细介绍变换器进行OFDM-MQAM的原理和具体实现方式,使能量信息一体化传输中的通信速率得到提升。建立变换器传输电能和信息的数学模型,在模型基础上计算分析输出电压纹波与数据信息传输的关系,并以此提出带有码元组合补零环节的OFDM-MQAM,大幅优化通信所引起的电压纹波。此外,针对多路载波引起的相位延时,通过所设计的解调环节避免OFDM系统的信道间和符号间干扰。最后通过一台交错并联的5 V/10 V Boost变换器完成了技术方法的实验验证。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
基金supported by the National Natural Science Foundation of China(61671468)。
文摘This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increase the spectrum efficiency,an improved preamble structure without guard symbols is derived at first. On this basis, instead of deriving the log likelihood function of power spectral density, joint estimation of the symbol timing offset and carrier frequency offset based on the preamble proposed is formulated into a bivariate optimization problem. After that, an improved genetic algorithm is used to find its global optimum solution. Conclusions can be drawn from simulation results that the proposed method has advantages in the joint estimation of synchronization.
文摘电力电子变换器通过功率与数据信息的复合调制,可使其在电能变换传输的同时进行数据信息的传输,从而实现能量信息一体化。该文以交错并联DC-DC变换器为研究对象,提出基于正交频分复用-多进制正交幅度调制(OFDM-MQAM)的能量信息一体化方法,并详细介绍变换器进行OFDM-MQAM的原理和具体实现方式,使能量信息一体化传输中的通信速率得到提升。建立变换器传输电能和信息的数学模型,在模型基础上计算分析输出电压纹波与数据信息传输的关系,并以此提出带有码元组合补零环节的OFDM-MQAM,大幅优化通信所引起的电压纹波。此外,针对多路载波引起的相位延时,通过所设计的解调环节避免OFDM系统的信道间和符号间干扰。最后通过一台交错并联的5 V/10 V Boost变换器完成了技术方法的实验验证。
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。
