Impact of time-selective fading on orthogonal space-time block coding

Coherent decoding of orthogonal space-time block codes (OSTBC) takes advantage of transmit/receive diversity to mitigate fading channel effects. Thanks to the orthogonality of OSTBC, a low-complexity linear maximum likelihood (ML) decoding becomes available if the receiver knows the channel state information (CSI). For OSTBC over time-selective channels, we develop an analytical expression of the bit error rate (BER) performance for linear decoding with minimum mean squared error (MMSE) channel estimates in place of the true channel. Based on the expression, we derive a BER performance limit in decision-directed mode where the channel is tracked with Kalman filtering. Numerical examples are provided to see the impact of time-selective fading on the BER performance.