Receiver implementation for a MIMO OFDM system

We present preamble and receiver design for a Q transmit L receive multi-input multi-output OFDM system. Tasks performed by the receiver are synchronization in time and frequency domains, followed by channel estimation and noise variance estimation. An algorithm is developed such that only Q OFDM symbols of a generalized length are required to perform functions of the preamble. Coarse time synchronization is performed using inherent periodicity in the preamble. Frequency offset estimation is then performed in the time domain, followed by residual frequency offset estimation in the frequency domain followed by fine time synchronization. The channel estimation algorithm is developed using least squares principle. Simulations are carried out for a broadband fixed wireless access scenario using a preamble with and without zero-padding of tones in the frequency domain.