Noise Cancellation in OFDM Systems Using Adaptive Complex Narrowband IIR Filtering

In this paper a very low sensitivity fourth-order complex band-pass filter section with independent tuning of the central frequency and the bandwidth is developed. A narrowband adaptive filter structure is formed around this section, using LMS algorithm to adapt the central frequency. The developed filter structure is providing a low computational complexity and a very fast convergence. We use this adaptive complex filter for noise cancellation in an OFDM transmission scheme and show that under certain conditions SNR gain and better bit error rate (BER) performance can be achieved.