Analytical performance evaluation of space time coded MIMO OFDM systems impaired by timing jitter

An analytical approach is presented to determine the impact of time selective fading, timing jitter and AWGN on the bit error rate performance of an OFDM system with DQPSK and QPSK modulation. The expression for the conditional BER conditioned on a given timing error and fading, is derived and the average BER is evaluated. The BER performance results are evaluated for different values of fading and jitter variances. The performance of the OFDM system in Rayleigh and Rician fading channels is also compared. Analytical approach is also developed to evaluate the BER performance of a quasi-orthogonal space-time block coded (STBC) OFDM system having multiple transmitting and single receiving antennas. The analysis is extended for a MIMO-OFDM system using the ldquoselection methodrdquo for combining multiple receiving antennas, which offers significant improvement in the system performance. The effects of increase in number of OFDM subcarriers and increase in Doppler frequency are also investigated.