Lattice-Reduction Aided Linear Equalization in Cyclic-Prefix System

Cyclic-prefix (CP) insertion in a single or multi-carrier system transforms the frequency-selective channel into a set of parallel flat channels, thus reducing the equalization complexity considerably. To harness the channel multipath diversity in this parallelized system the use of error control codes and/or linear precoding are proposed in the literature. A more recent result shows that maximum diversity can be achieved by lattice-reduction aided equalization together with precoded OFDM transmission. In this paper, we show that full diversity lattice-reduction is possible {em without} requiring either precoding or error control codes. In earlier work it was shown that some cyclic-prefix systems have a diversity that is rate-dependent; we show that lattice-reduction diversity does not follow the same pattern of behavior. We also explore and expose important distinctions between diagonal and non-diagonal equalization for cyclic prefix systems.