Iterative frequency-domain equalization for single-carrier systems in doubly-dispersive channels

Abstract

Frequency-domain equalization (FDE) offers an attractive alternative to time-domain equalization in systems that communicate over large-delay-spread channels. Traditionally, FDE leverages the fact that time-domain convolution is equivalent to frequency-domain multiplication and the fact that time/frequency conversion is efficiently handled by the fast Fourier transform (FFT). In doubly dispersive channels, i.e., quickly varying large-delay-spread channels, the traditional FDE methods fail due to the time-varying property of the channel. Here we present a new FDE that is based on Doppler channel shortening, soft iterative interference cancellation and block decision feedback. Numerical simulations show that the proposed technique outperforms the well-known FIR-MMSE-DFE in both performance and complexity.