Date Added: Nov 2012
This paper studies a distributed OFDM system with multiple quasi-synchronous users, where different users may transmit different numbers of parallel data streams. The distinction from most existing work is that the multipath channels for different users have significantly different Doppler scales. Such a setting with two single-transmitter users was first studied in a recent publication by Tu et al. This paper presents two iterative receivers, termed as Multi-User Detection (MUD)-based and Single-User Detection (SUD)-based receivers, respectively. The MUD-based receiver adopts a frequency-domain-oversampling front end on each receive element, then performs joint channel estimation and multiuser data detection iteratively.