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最大多普勒扩展作为信道时变性的直接反映,是网格正交频分复用LOFDM(Lattice Orthogonal Frequency Division Multiplexing)系统自适应策略的重要参数之一。准确的最大多普勒扩展估计对于LOFDM系统发送端信号设计以及自适应策略实现十分重要。文章针对LOFDM系统的特殊信号结构以及双散射信道的快时变特性,采用DFT-BEM信道模型近似快时变信道响应,结合快时变信道下LOFDM系统块传输接收方案,利用梳状导频辅助估计多普勒域平均信道频率响应,在此基础上利用信道响应估计值的时间相关函数提出了基于F范数的信道最大多普勒扩展估计算法。理论分析与计算机仿真表明提出的估计算法具有良好的均方误差性能和收敛性能。
The maximum Doppler spread, as a direct reflection of the time-variant channel, is one of the important parameters of the adaptive strategy of the Lattice Orthogonal Frequency Division Multiplexing (LOFDM) system. The accurate maximum Doppler spread estimation is very important for the signal design of LOFDM system and the realization of adaptive strategy. Aiming at the special signal structure of LOFDM system and the fast time-varying characteristics of LOFDM system, the DFT-BEM channel model is used to approximate fast time-varying channel response. Combined with LOFDM block transmission and reception scheme in fast time-varying channel, The average channel frequency response of Doppler domain is estimated. Based on the time correlation function of channel response estimation, a maximum Doppler spread estimation algorithm based on F-norm is proposed. Theoretical analysis and computer simulation show that the proposed estimation algorithm has good mean square error performance and convergence performance.