Impact of synchronization errors on Alamouti-STBC-based cooperative MIMO schemes

The effect of synchronization errors on the performance of a cooperative MIMO scheme that uses the Alamouti space-time code is studied in this paper. The focus is on finding a lower bound of the received Signal to Interference and Noise Ratio (SINR). The synchronization error, caused by the distributed nature of the scheme, is considered as inaccurate channel state information, which is modeled as an additive deterministic norm-bounded inaccuracy matrix. A closed-form expression is derived for the SINR. Using this, a closed-form expression of the Bit Error Rate (BER) in the high SNR regime for the worst case error vector is also derived. This worst case performance is of interest to system designers as it helps them to design the system with specific guarantees about the outage behavior. One interesting observation from the presented results is that the larger the synchronization error gets, the quicker we reach the interference limited high SNR region, in which the `MIMO benefits' are absent.