为解决高速移动环境下时变信道的估计问题,提出1种适用于高速铁路环境的WiFi时频结合信道估计算法.该算法将基于导频的方法、基于中导码的方法和Kalman滤波的方法进行有效结合,实现了时频域的信道估计.将利用中导码估计出的信道估计值作为初始信道状态值,利用导频估计Kalman滤波参数,根据Kalman滤波方程,不断修正信道的状态值,最后得到所有符号处的信道估计值.研究表明:这种时频结合的中导码插入信道估计算法,比仅用前导码或中导码的方法有较明显的优势;随着移动速度的提高,为得到相同的估计性能,中导码的插入间隔应相应减少.%To estimate time-varying channel estimation in the high-speed mobile scenario,a time-frequency combination channel estimation algorithm in WiFi applicable to high-speed railway environment was proposed. The algorithm effectively combined pilot-based method, midamble-based method and Kalman filter-based method to achieve the channel estimation in time-frequency domain.The estimation value achieved by midam-bles served as the initial channel state value to estimate the Kalman filter parameters using pilot.The complete channel state values were obtained by continually refreshing the channel state value through Kalman filter equa-tion.The simulation results showed that the time-frequency midamble-inserted channel estimation algorithm was superior to the estimation algorithm using preamble or midamble alone.With the increase of speed,the in-sertion interval between midambles should be shortened accordingly so as to guarantee estimation accuracy.
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