基于多普勒辅助迭代的高速OFDM系统信道估计方法

摘要

For high mobility OFDM systems, fast time-variation of fading channel destroys the orthogonality between sub-carriers of OFDM and lead to serious inter-carrier interference. A Doppler-assisted iterative channel estimation method is proposed for the systems. In the method, pilot tone symbols are interpolated to proper position of OFDM symbols, channel coefficients at pilot position are obtained through iterative estimation using least mean square, and then the channel coefficients of numerical symbols position are obtained through a weighted time-domain interpolation. The interpolation weight coefficients are pertinent to Doppler frequency shift, and are calculated by the mobile velocity of the receiver. During the process of pilot channel coefficients iterative estimation, the detected data symbols are fed back as new pilots to pilot channel estimation module to carry out iterative estimation. Simulation analyses show that the proposed algorithm performs stable and does affected by Doppler shift when the receiver moving at a speed up to 300km/h, it can give channel estimation results in condition of the precision approaching the best channel.%在高速移动环境下,衰落信道的快时变性破坏OFDM子载波间的正交性并产生严重的载波间干扰,由此提出一种多普勒辅助迭代的信道估计方法.该方法在OFDM符号的适当位置插入导频符号,通过最小均方法迭代估计获得导频位置的信道信息,再由加权的时域插值获得数据符号位置的信道信息.插值加权系数与多普勒频移相关,由接收端的移动速度计算得出.在导频信道信息的迭代估计过程中,将检测到的数据符号作为新的导频信息反馈到导频信道估计模块进行迭代估计.仿真分析表明:在接收机移动速度达到300km/h时,该方法的性能稳定,不受多普勒频移影响,可以给出精确度逼近最佳信道条件下的信道估计结果.