Analytical performance of OFDM radio link under RX I/Q imbalance and frequency-selective Rayleigh fading channel

In this paper, we study the impact of an important RF impairment inside direct-conversion receiver, namely the I/Q imbalance, on the performance of OFDM radio link over frequency-selective Rayleigh fading channel. Closed-form expressions for link performance, in terms of detection error rate, ergodic capacity and outage capacity, under both frequency-selective RX I/Q imbalance and noisy frequency-selective fading channel are obtained as functions of image rejection ratios (IRRs) of the receiver front-end, average channel power delay profile as well as received SNR. The analysis results are then verified using extensive computer simulations. In general, the analysis shows that the performance of OFDM radio link under RX I/Q imbalance not only depends on the property of impairment itself but also depends on the correlation property of transmission channel. In this context, the proposed analysis provides fundamental understanding and very efficient tools for both circuit and system designers to accurately evaluate the I/Q imbalance effects in the OFDM radio link.