Iterative Equalization Based on Expectation Propagation: A Frequency Domain Approach

A novel single-carrier frequency domain equalization (SC-FDE) scheme is proposed, by extending recent developments in iterative receivers that use expectation propagation (EP), a message passing formalism for approximate Bayesian inference. Applying EP on the family of white multivariate Gaussian distributions allows deriving double-loop frequency domain receivers with single-tap equalizers. This structure enables low computational complexity implementation via Fast-Fourier transforms (FFT). Self-iterations between the equalizer and the demapper and global turbo iterations with the channel decoder provide numerous combinations for the performance and complexity trade-off. Numerical results show that the proposed structure outperforms alternative single-tap FDEs and that its achievable rates reach the channel symmetric information rate.