A New Carrier Frequency Offset Estimation Approach for Distributed Line of Sight Millimeter Wave MIMO Systems

The paper proposed a new carrier frequency offset (CFO) estimation method for distributed line of sight (DLOS) millimeter wave MIMO systems. We assume a DLOS multipath MIMO channel with independent CFOs for both the transmitters and receivers. The proposed method consists of two stages. Firstly, with the assumption that only the target transmitter has CFO, while other transmitters don't have CFOs, the multi-dimensional estimation problem is reduced into one dimensional, based on which the new receiver model is deduced and the coarse CFO (CCFO) estimation algorithm is proposed. The residual CFOs are estimated after the equalizer with a multi-stages phase locked loop (MSPLL) approach. Simulation results show that the proposed method works well in the DLOS millimeter wave MIMO systems. There is nearly no performance loss due to the CFO impairments compared with Cramer-Rao bound at high signal to noise ratio (SNR).