Joint maximum-likelihood frequency synchronization and channel estimation in MIMO-OFDM systems with timing ambiguity

In this paper, based on two different signal models, two different maximum-likelihood (ML) schemes for joint carrier frequency offset (CFO), timing ambiguity, and channel estimation in multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems have been proposed. The first scheme jointly estimates the timing offset, CFO and MIMO channel coefficients, but the complexity is high due to the need of multi-dimensional searches. The second scheme has a reduced complexity, but its performance slightly degrades compared with the first one. The cramer-rao bounds (CRBs) are also developed to evaluate the performance of the proposed schemes. Simulation results show that the performances of the proposed schemes are quite satisfying.