A new decision feedback equalization method for digital microwave radio

A novel equalization method using the decision feedback equalizer with a variable reference position (VR-DFE) is proposed. The VR-DFE is composed of a forward equalizer, whose reference position is variable depending on the channel response, and a backward equalizer. The VR-DFE employs an adaptation algorithm which enables the reference position to vary according to the change in fading from minimum phase to nonminimum phase and vice versa. The VR-DRE has great advantages in nonminimum-phase fade compared with an ordinary DFE. Computer simulations for 16 quadrature amplitude modulation (QAM) digital radio show that the VR-DRE copes well with the rapid transition to the nonminimum phase 40-dB fade in 7000 symbol time slots without producing a decision error