A MMSE Joint Feedback Feed-forward Equalizer for FBMC-OQAM Baseband Receiver in the 60 GHz Band

In this paper, a minimum mean square error (MMSE) joint feedback feed-forward equalizer (MJFFE) is proposed to deterministically suppress the inter-symbol interference and inter-carrier interference that arose from the filter bank multi-carrier in a long multipath channel of the 60-GHz indoor wireless transmission. The decision device is discarded in the decision feedback loop to reduce error propagation while at the same time applying the MMSE criterion to prevent over compensation influenced by additive white Gaussian noise. As a result, in an non-line-of-sight (NLOS) channel with 7.65-ns rms delay spread, a 3-tap MJFFE provides 3-dB improvement at the bit error rate (BER) 10−2 crossing and improve error floor effect at the BER 10−3 crossing, as compared with the 1-tap zero-forcing equalizer. Furthermore, the proposed equalizer coefficients calculation based on linear convolution for the MJFFE is also presented. The hardware complexity achieves 50% reduction by using several methods including multiplexing, memory sharing, and computation element sharing.