定时估计是准确实现OFDM(orthogonal frequency division multiplexing)系统同步的关键技术之一.实际应用中,为了提高系统对多径时延扩展的抵抗能力,还应尽量减少符号的定时同步误差.为了提高符号定时部分的估计精度,提出了改进算法.算...定时估计是准确实现OFDM(orthogonal frequency division multiplexing)系统同步的关键技术之一.实际应用中,为了提高系统对多径时延扩展的抵抗能力,还应尽量减少符号的定时同步误差.为了提高符号定时部分的估计精度,提出了改进算法.算法中设计了一种具有良好自相关特性的新训练序列,结合新序列的数据结构,算法由粗估计和细估计2部分完成.Matlab仿真表明,与传统算法相比,在高斯噪声和多径信道的影响下,所提出的算法具有较小的均方误差,抗干扰能力强的特点,并为频率偏移估计打下了良好的基础.展开更多
The 3780-point FFT is a main component of the time domain synchronous OFDM (TDS-OFDM) system and the key technology in the Chinese Digital Multimedia/TV Broadcasting-Terrestrial (DMB-T) national standard.Since 3780 is...The 3780-point FFT is a main component of the time domain synchronous OFDM (TDS-OFDM) system and the key technology in the Chinese Digital Multimedia/TV Broadcasting-Terrestrial (DMB-T) national standard.Since 3780 is not a power of 2,the classical radix-2 or radix-4 FFT algorithm cannot be applied directly.Hence,the Winograd Fourier transform algorithm (WFTA) and the Good-Thomas prime factor algorithm (PFA) are used to implement the 3780-point FFT processor.However,the structure based on WFTA and PFA has a large computational complexity and requires many DSPs in hardware implementation.In this paper,a novel 3780-point FFT processor scheme is proposed,in which a 60 63 iterative WFTA architecture with different mapping methods is imported to replace the PFA architecture,and an optimized CoOrdinate Rotation DIgital Computer (CORDIC) module is used for the twiddle factor multiplications.Compared to the traditional scheme,our proposed 3780-point FFT processor scheme reduces the number of multiplications by 45% at the cost of 1% increase in the number of additions.All DSPs are replaced by the optimized CORDIC module and ROM.Simulation results show that the proposed 3780-point FFT processing scheme satisfies the requirement of the DMB-T standard,and is an efficient architecture for the TDS-OFDM system.展开更多
文摘定时估计是准确实现OFDM(orthogonal frequency division multiplexing)系统同步的关键技术之一.实际应用中,为了提高系统对多径时延扩展的抵抗能力,还应尽量减少符号的定时同步误差.为了提高符号定时部分的估计精度,提出了改进算法.算法中设计了一种具有良好自相关特性的新训练序列,结合新序列的数据结构,算法由粗估计和细估计2部分完成.Matlab仿真表明,与传统算法相比,在高斯噪声和多径信道的影响下,所提出的算法具有较小的均方误差,抗干扰能力强的特点,并为频率偏移估计打下了良好的基础.
基金Project supported by the National Natural Science Foundation of China (No.61071129)the Science and Technology Department of Zhejiang Province,China (Nos.2008C21088,2011R10035,and 2011R09003-06)
文摘The 3780-point FFT is a main component of the time domain synchronous OFDM (TDS-OFDM) system and the key technology in the Chinese Digital Multimedia/TV Broadcasting-Terrestrial (DMB-T) national standard.Since 3780 is not a power of 2,the classical radix-2 or radix-4 FFT algorithm cannot be applied directly.Hence,the Winograd Fourier transform algorithm (WFTA) and the Good-Thomas prime factor algorithm (PFA) are used to implement the 3780-point FFT processor.However,the structure based on WFTA and PFA has a large computational complexity and requires many DSPs in hardware implementation.In this paper,a novel 3780-point FFT processor scheme is proposed,in which a 60 63 iterative WFTA architecture with different mapping methods is imported to replace the PFA architecture,and an optimized CoOrdinate Rotation DIgital Computer (CORDIC) module is used for the twiddle factor multiplications.Compared to the traditional scheme,our proposed 3780-point FFT processor scheme reduces the number of multiplications by 45% at the cost of 1% increase in the number of additions.All DSPs are replaced by the optimized CORDIC module and ROM.Simulation results show that the proposed 3780-point FFT processing scheme satisfies the requirement of the DMB-T standard,and is an efficient architecture for the TDS-OFDM system.
