Bit error rate calculation for OFDM direct conversion receivers with synchronization and channel estimation imperfections

In this paper we present an analytical approach to evaluate the M-QAM bit error rate (BER) of OFDM direct conversion receivers subject to carrier frequency offset (CFO), channel estimation error, outdated channel state information and flat receiver I/Q imbalance in Rayleigh time and frequency selective fading channels. Based on correct modeling of the correlation between channel estimates and received signals with carrier frequency offset and receiver I/Q imbalance, the bit error rate can be numerically evaluated by averaging bit error rates on different subcarriers using an analytical expression of triple integrals. The results illustrate that the analysis can approximate the simulative performance very accurately if the power delay profile of fading channels, the receiver I/Q imbalance parameters and carrier frequency offset are known.