Practical Frequency-Domain Decision Feedback Equalization based on Expectation Propagation
Abstract
This work tackles the problem of implementing frequency-domain (FD) Decision Feedback Equalization (DFE) algorithms derived from the Expectation Propagation (EP) framework under strict computational complexity and latency constraints. The EP soft-symbol feedback reliability estimation can be advantageously replaced by an offline pre-calculated function, which not only lowers the complexity of the EP-based FD DFE but also increases its robustness under challenging channels. Secondly, a substantial complexity reduction is obtained by approximating the input-output transfer functions of the EP soft mapper with linear piece-wise functions. The overall performance of the proposed practical receiver has a negligible loss with respect to the original EP-based DFE proposal.