Iterative (TURBO) IQ Imbalance Estimation and Correction in BICM-ID for Flat Fading Channels

TURBO principle has been exploited gainfully to implement many receiver functions. RF front-end impairments are a serious issue in high spectral efficient applications. IQ imbalance is one of these impairments and in this work, we study the issue of IQ imbalance correction using baseband signal processing techniques. In particular, we propose an estimation technique based on EM algorithm. Such a technique is developed rather intuitively for the case of a Bit Interleaved Coded modulation - Iterative Detection (BICM-ID) receiver for burst mode communications. The resulting TURBO IQ Decorrelator is embedded in the BICM-ID loop, is blind in the sense that it does not require any training symbols or tones. Performance is simulated for 64QAM under flat fading channel conditions.