Semi-blind multi-channel identification in asynchronous multi-user OFDM systems
Hyejung Jung, M.D. Zoltowski · 2005
This paper presents a novel subspace-based semiblind channel identification scheme for asynchronous multiuser orthogonal frequency division multiplexing (OFDM) systems with antenna diversity. The inherent property of asynchronous OFDM signals allows separation of the desired user's channel from the interfering users' channels via subspace decomposition. Moreover, the proposed semiblind channel estimator overcomes practical limitations of the conventional subspace method due to unknown channel lengths and noise-corrupted data by employing pilot symbols. Simulation results demonstrate that the semiblind channel estimator significantly outperforms a pilot-only estimator when most part of the noise subspace is exploited.