A Robust Compensation Scheme for IQ Imbalance and Frequency Offset in Direct-Conversion DVB-T Receiver

One of the main challenges in direct-conversion receivers is matching I and Q signal branches. Direct-conversion receivers based on orthogonal frequency division multiplexing are also sensitive to frequency offsets occurring between the transmitter and the receiver. The presence of these two impairments together requires that they be compensated through joint post signal processing, which can become very challenging if the received signal is suffering from multi-path fading. In this paper, a robust compensation scheme for both the IQ imbalance and frequency offset in the presence of multi-path fading is presented. Computer simulations have shown that the proposed scheme is effective in compensating even quite large IQ imbalance errors to yield an acceptable bit error rate of less than 2times10^-4for both the AWGN and Ricean channels