Joint estimation of frequency offset and channel parameters for MIMO-OFDM systems with PAPR reduction precoder

Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is very sensitive to the carrier frequency offset (CFO), which not only affects the channel estimation but also the selection of a minimum error probability based precoder for peak-to-average power ratio (PAPR) reduction such that the system performance will degrade. This paper presents the joint scheme of CFO) and channel estimation in the MIMO-OFDM systems with the minimum error probability based precoder for reducing PAPR. First, a minimum error probability based precoding matrix to reduce the PAPR of OFDM signals is designed. The CFO and CIR estimators based on the expectation maximization (EM) algorithm with an iterative scheme are developed to execute the estimations. To reduce computational complexity, a simpler coarse CFO estimator is carried out before the fine estimation so that a more accurate and faster convergent estimate can be attained. Simulation results show that the CFO estimator with a coarse initial estimate not only has an excellent performance at reduced computational complexity, but also makes the CIR estimation achieve almost ideal performance.