A blind channel identification algorithm for OFDM systems

Abstract

SUMMARYIn this letter, we proposed a new blind channel estimation method for orthogonal frequency division multiplexing (OFDM) systems. The algorithm is based on the subspace approach and makes use of cyclic prefix (CP) redundancy. It does not require any modification of the transmitter and therefore applies to most existing OFDM systems. We also take consideration of the presence of null subcarriers in standardized OFDM systems. Compared with some existing methods, this approach has the following attractive properties: it has a lower computational complexity; it can estimate channels for OFDM systems with insufficient CP; it performs well at low SNR; it performs well no matter where the channels' zero locations are and is robust to channel order overestimation. Theoretical analysis and simulation results are provided to verify the above facts.

A simplified MAP channel estimator for OFDM systems under Rayleigh fading

“…There have been many papers dealing with channel estimation for OFDM systems under fading, which are based on maximum likelihood (ML) or Maximum A Posteriori (MAP) techniques, and [1][2][3][4][5][6][7][8][9][10][11] provide a good sample of the results obtained in this area. The ML-based estimators have acceptable complexity, but since they ignore the correlation between subchannels they suffer from a high mean-square error (MSE), especially if the system operates with low signal-to-noise ratios (SNR) [6].…”