Effects of imperfect channel estimation on space-time coding performance

The effect of imperfect channel estimation on the bit error rate (BER) of multiple-input multiple-output communication systems utilising space-time coding is investigated. A multipath channel is considered and a given level for the channel estimation error is assumed. The receiver employs an equaliser to reduce the ISI in the received signal. A closed-form expression for the SNR at the output of the equaliser that employs the results of the channel estimation is derived. The theoretical SNR derived is used as a basis to assess the performance of the system. Results are applicable to any channel estimation technique. Analysis shows that the deterioration of performance in the multiple transmit antenna scheme outweighs the benefits achieved over the single antenna case when the SNR and channel estimation error are large. The degradation in the transmit diversity scheme exceeds 8 dB to achieve a BER of 10^-4 when the channel estimation error is 5% relative to the perfect channel estimation case.