Robust joint fine timing synchronization and channel estimation for MIMO systems

This paper proposes a joint timing synchronization and channel estimation scheme for multiple-input single-output or multiple-input multiple-output communication systems. All timing offsets and channel impulse responses (CIR) of different transmit–receive links are obtained based on a well-designed training sequence arrangement. The proposed approach consists of three stages at each receive antenna. First, a coarse timing offset (CTO) estimation algorithm is performed to estimate the CTO and the inter-transmitter delays. Then, relative timing indices and the corresponding CIR estimates of all transmit–receive links at the second stage are obtained using the generalized maximum-likelihood estimation based on a sliding observation vector. Finally, the fine time adjustment based on the minimum mean-squared error criterion is performed. From the simulation results, the proposed approach has excellent timing synchronization performance under several channel models at very low signal-to-noise ratio which is smaller than 1 dB. Also, the channel estimation performance in the proposed scheme approaches to the Cramér–Rao bound.