A Blind Post-FFT User-by-user Beamforming Algorithm for Multiuser OFDM Systems

Abstract-Recently, Peng and Chi et al. proposed a block-by-block blind post-FFT multistage beamforming algorithm (MSBFA) based on subcarrier averaging for a multiuser orthogonal frequency division multiplexing (OFDM) system, which works well under multipath block fading channels even in the presence of correlated paths. However, the MSBFA is a sequential path-by-path detection algorithm, thereby resulting in long detection latency as the total number of paths of all the active users is large. In this paper, a blind multistage user-by-user beamforming algorithm (UUBFA) is proposed, which, in contrast to the MSBFA, detects all the path signals for one individual user and meanwhile achieves the maximum diversity gain through a blind maximum ratio combining processing at each stage. In addition to achieving the same performance as the MSBFA, the parallel signal processing structure of the proposed UUBFA is well suited to software and hardware implementations. I