Narrowband interference mitigation in OFDM systems

The performance of an orthogonal frequency division multiplexing (OFDM) system is degraded in the presence of narrowband interference (NBI). This degradation arises from spectral leakage of the interference power during demodulation, corrupting many subcarriers. The prediction-error filter (PEF) is introduced as a means for mitigating the NBI in the time-domain prior to demodulation. In the uncoded case, the PEF is shown to mitigate the interference, however, the performance is limited by an irreducible error floor due to the data subcarriers that are notched out. In the coded case, the coding provides a way for recovering the removed subcarriers. The PEF is compared with Bayesian erasure insertion over a range of SIRs and it is seen that the PEF performs best for all SIRs. The PEF acts an erasure insertion mechanism by inserting erasures via a notch around the tones closest to the interference, while leaving the surrounding tones unaffected.