双选择信道下OFDM系统中一种基于新Kalman滤波估计的Turbo均衡

Turbo Equalization Based on a New Kalman Filter for OFDM over Doubly-Selective Channels

在OFDM系统中,信道的快速时变性破坏了子载波间的正交性,从而导致子载波间干扰(ICI),降低了系统性能。该文针对双选择信道的时变特性,提出了一种新的Kalman滤波信道估计算法,将其应用于过采样的复指数基扩展模型(OCE-BEM),从而将一个OFDM符号周期内信道参数时变的问题转化为参数时不变问题,同时,将这种新的Kalman滤波器与基于ICI抑制的低复杂度LMMSE Turbo均衡器相结合,并辅以循环冗余码校验(CRC)控制算法迭代次数,从而不需要更多的导频符号,在保证算法性能的基础上,减小算法的计算时延和复杂度。理论分析和仿真结果表明,该文给出的方法在双选择信道下能够有效地跟踪信道变化并抑制ICI影响。

In OFDM systems, the channel fast variations destroy the orthogonality among sub-carriers, resulting in inter-carrier interference （ICI） which degrades the system performance. Aiming at time-varying characteristic of doubly-selective channels, a channel estimation algorithm is proposed by a new Kalman filter, and is applied to the Oversampled Complex Exponential Basis Expansion Model （OCE-BEM）, changing the variable channel parameters in the period of one OFDM symbol into invariable ones. Meanwhile, this new Kalman filter is combined with the low complexity LMMSE ~lrbo equalizer based on ICI suppression, and CRC checkout is used to control the iteration times of the algorithm, so it need not many pilot symbols in practice, still can ensure the algorithm performance and reduce the time-delay and complexity of this algorithm.