一种基于周期失配序列的OFDM时变信道估计

摘要

A new approach which using to add periodic mismatched sequence to OFDM signals as training sequence to channel estimation in OFDM systems is proposed. The energy of periodic sequence mainly concentrates in a few pilot points, so after FFT transformation, periodic mismatched sequence is inserted into OFDM signals. To calculate the cross- correlation between the received mismatched sequence in a few pilot points and the circular shifted mismatch filter coefficient solves the channel impulse response. Comparison has been done between the proposed algorithm and the existing algorithm in the time -varying multipath channel. Simulation results show that the new algorithm effectively reduces the value of MSE and BER in low complexity. Especially in the OFDM systems with more sub - carrier number and low SNR, the performance is improved obviously.%提出了一种将周期失配序列插入到OFDM符号中作为训练序列进行信道估计的新方法.由于周期序列的能量主要集中在少数几个导频点上,所以将周期失配序列进行FFT变换后插入到OFDM符号中,对接收到的少数几个导频点上的失配序列进行IFFT变换后与失配滤波器循环移位序列做相关运算,得到信道冲击响应.本文在多径时变信道下,对新算法和已有算法进行了仿真.结果表明,新算法在计算复杂度低的情况下,有效降低了信道的MSE值和BER值,特别是在OFDM系统子载波数多且SNR低的情况下,性能改善更加明显.