Preamble-based channel estimation in asynchronous FBMC-OQAM distributed MIMO systems

This paper investigates downlink channel estimation in a distributed MIMO context employing Filter Bank-based Multi-Carrier Offset QAM (FBMC-OQAM) modulation. Training preambles are constructed based on two different subcarriers assignment schemes (SAS), with the aim of freeing the estimation procedure from the effects of the multi-stream interference (MSI). The Linear Minimum Mean Squared Error (LMMSE) estimator is considered for computing estimates of the channel frequency responses over the entire frequency band and shown to be robust to ill-conditioning associated with the SAS. The application of the different SAS to FBMC-OQAM is evaluated via simulations in an unsynchronized scenario. The performances are compared with the corresponding fully synchronized CP-OFDM scenario. The results demonstrate the robustness of FBMC-OQAM to asynchronism and reveal the advantages of each SAS in various situations.