On the Narrowband Interference Cancellation Scheme in OFDM Communication Systems in Frequency Selective Fading Channels

A common impairment in both wireless and wireline orthogonal frequency division multiplexing (OFDM) schemes is narrowband interference (NBI). NBI has the detrimental effect of making the tones on which the NBI falls and in some cases neighboring tones unusable, thus reducing the effective signal-to-noise ratio (SNR) of the system. Some examples of mechanisms that generate NBI are switched mode power supplies and legacy communication systems [1]. Recently, a novel method for minimizing the SNR degradation due to NBI was proposed in [2], [3] which required knowledge of only the NBI frequencies. The method notches only one tone per interferer. In this paper, we analyze how the above algorithm performs in frequency selective channels. Theoretical SNR bounds are derived as a function of the number of interferers, channel gains and noise power and validated via numerical simulations. The bounds show that under the assumption of an idealized front-end and ideal NBI frequency estimation, the performance of the algorithm does not depend on the NBI power or phase. A sensitivity analysis of the algorithm due to NBI frequency estimation errors is also performed and the theoretical results are validated via numerical simulations.