Blind channel estimation for multicarrier systems with narrowband interference suppression

We present herein a novel blind channel estimator for multicarrier (MC) systems in the presence of unmodeled narrowband interference. A generalized multichannel minimum variance principle is invoked to design an equalizing filterbank that preserves desired signal components and suppresses the overall interference. While a channel estimate may be obtained by directly maximizing the filterbank output power through multidimensional nonlinear searches, such an approach is computationally prohibitive and suffers local convergence. To overcome this difficulty, we derive an asymptotically (in SNR) tight lower bound of the filterbank output power and use it for channel estimation, which reduces the problem to a quadratic minimization. Numerical examples show that the proposed scheme compares favorably with a subspace blind channel estimator in the presence of unknown narrowband interference.