OFDM Narrowband Interference Estimation Using Cyclic Prefix Based Algorithm

OFDM systems experience BER degradation in the presence of narrowband interference (NBI). We propose a novel NBI cancellation algorithm for a wideband OFDM receiver. Modelling the NBI as a single-tone sinusoid, subspace-based (SB) methods can be used to estimate it. However, direct application of SB methods to the received signal yields poor results except when the system is operating at very low SIR. Our algorithm exploits the redundancy inherent in the cyclic prefix of the OFDM system to remove the information bearing component of the received signal prior to the estimation of NBI by using SB methods. We estimate the NBI by applying SB methods to the resulting signal. Simulation results show a significant improvement in performance with the proposed scheme.