Three-Stage Treatment of TX/RX IQ Imbalance and Channel with CFO for SC-FDE Systems

Direct-conversion transceiver obtains increasing attentions due to its low power consumption, but it confronts with serious IQ imbalance. In this paper, a three-stage treatment of transmitter/receiver (TX/RX) IQ imbalance and channel, in the presence of carrier frequency offset (CFO), is proposed for single-carrier-frequency-domain-equalization (SC-FDE) systems. First, RX IQ imbalance and CFO are handled with a repetitive preamble. Second, joint responses of TX IQ imbalance and channel are estimated by designing another preamble via complementary Golay codes. Third, joint compensation of TX IQ imbalance and time-varying channel is conducted using the minimal-mean-square-error criterion. Simulations are presented to verify the proposed method, in terms of normalized mean square error for the estimation and bit error rate for the overall system.