MMSE Equalization for Zero Padded Multicarrier Systems with Insufficient Guard Length

We derive a block linear MMSE equalizer suitable for zero padded multicarrier systems with insufficient guard length. The proposed equalizer is not limited to systems using the IFFT/FFT pair (like in DMT or OFDM), but to any multicarrier system that can be modelled as a pair of perfect reconstruction filter banks. As the computational complexity of the equalizer can be high, an efficient implementation based on the Cholesky factorization is developed. Compared to the traditional zero-forcing approach, experiments show that in the presence of interblock interference (IBI), the proposed equalizer performs significantly better, regardless of the signal-to-noise ratio (SNR). In the absence of IBI (i.e. when the guard interval is sufficiently long), improvements have also been observed at low SNR