Joint Channel Estimation And Equalization Scheme In Ofdm System

In the next B3G/4G mobile communication systems, OFDM will become a key technology. It can suppress multipath fading, and it has highly spectral efficiency. For suppress fading, the channel estimation and equalization is very important for OFDM systems.The channel estimation method can be classified into blind methods and non-blind methods. The non-blind methods need to use pilot, especially in frequency selectivity channels, a large number of pilot will decrease the spectral efficiency. Therefore, the blind method becomes a new research focus.A novel joint blind channel estimation and turbo equalization algorithm is proposed for orthogonal frequency-division multiplexing (OFDM) system in this paper. It has been proved that, blind channel estimation based on linear precoding can obtain channel information exactly. However, the precoding will cause inter-symbol interference (ISI). With the existence of ISI, the bit error rate (BER) performance of OFDM will be degraded seriously. In our proposed algorithm, we plan to combine this blind channel estimation algorithm with turbo equalization. On the one hand, turbo equalization can eliminate the ISI and improve system's performance; On the other hand, the priori information provided by channel decoder conversely can be employed to boost the accuracy of blind channel estimation. Simulation results show that, compared with existing methods, our proposed algorithm can achieve better channel estimation accuracy and BER performance.