Sequential LSQR-based ICI equalization and decision-feedback ISI cancellation in pulse-shaped multicarrier systems

We propose a frequency-domain method for equalizing intercarrier interference (ICI) and intersymbol interference (ISI) in multicarrier transmissions over rapidly time-varying and strongly delay-spread channels. Postcursor ISI is cancelled by a decision-feedback structure, and ICI is equalized by a sequential version of the recently proposed LSQR equalizer, based on a band approximation for the frequency-domain channel matrix. The sequential LSQR equalizer uses an interference cancellation scheme with reliability-based sorting of sets of subcarriers. This approach is shown to yield excellent performance at moderate complexity. A pulse-shaped multicarrier system is considered because of its generality and advantages. This framework includes cyclic-prefix OFDM as a special case.