Reduced rank equalization for precoded OFDM systems

In precoded OFDM systems, zero-forcing (ZF) equalizers suffer from noise enhancement and error spreading problems. A minimum mean square error (MMSE) equalizer can mitigate the problems and improve system performance, however, it has relatively higher complexity and is sensitive to the estimation accuracy of noise variance. In this paper, based on the principle of reduced-rank signal processing, we propose reduced-rank equalizers for precoded OFDM systems. These equalizers can achieve performance close to MMSE equalizers while with complexity similar to ZF equalizers.