Reduction of Inter Carrier Interference using Extended Kalman Filter in OFDM Systems for Different Channel Models

Orthogonal Frequency Division Multiplexing (OFDM) is a multirate data transmission technique. The main drawback of OFDM is, its sensitivity to frequency offset in the channel, which may be caused by Doppler shift in the channel. This introduces loss of Orthogonality of Carrier Signals. Intercarrier Interference (ICI) occurs due to the loss of Orthogonality. The bit error rate (BER) increases rapidly with increasing frequency offsets. This is a main restriction in OFDM systems. The existing approaches to reduce ICI can be categorized as frequency-domain equalization, time windowing and the ICI self cancellation scheme. To reduce ICI Self cancellation method is easy to implement and gives better results for lower modulation. For higher modulation schemes, it does not offer much increase in performance. So we propose Extended Kalman filter (EKF) method to overcome the drawback of self cancellation method. Then, different Modulation Schemes are adopted for the analysis along with EKF.