A New Time and Frequency Synchronization Scheme for Distributed MIMO-OFDM Systems

In the distributed multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems, different frames from different transmitters are not aligned in the time domain, and have different carrier frequency offsets (CFOs). Estimation of these time offsets and multiple CFOs is a crucial and challenging task. In this contribution, a new preamble structure is proposed, and the corresponding time and frequency offsets estimation algorithms are also presented for distributed MIMO-OFDM systems. The coarse timing synchronization is accomplished by using the symmetric conjugate of the training symbol and the fine timing synchronization is accomplished by moving correlation. The fractional frequency offset is estimated by using the phase difference of the received signal and the integral frequency offset is estimated by utilizing the good autocorrelation of the training symbol in frequency domain. The analysis and the simulation results show that the proposed preamble structure and synchronization scheme have a satisfactory performance in distributed MIMO-OFDM systems.