Time Synchronization Issues for Quasi-Orthogonal Space-Time Block Codes

This paper deals with some of the problems arising in multiple-input multiple-output (MIMO) antenna systems, when the receiver´s clock is not synchronized to the modulator. Considering that the spatial diversity is exploited through quasi-orthogonal space-time block codes (QOSTBC), we examine the influence of the remaining timing offset on the performance of the system, after coarse timing acquisition has been carried out at the receiver. Specifically, by utilizing the statistical properties of the channel paths and simulating the time error as a uniformly distributed random variable, we show that the average trace of the diversity gain matrix (DGM) undergoes a decrease with respect to the ideal case of zero intersymbol interference (ISI).