Performance Results of Two Iterative Receivers for Distributed MIMO OFDM With Large Doppler Deviations

This paper studies a distributed orthogonal frequency-division multiplexing (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. (2010). This paper presents two iterative receivers, termed as multiuser detection (MUD)-based receivers and single-user detection (SUD)-based receivers. 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. The SUD-based receiver adopts conventional single-user processing modules, but adds a critical step of multiuser interference (MUI) cancellation, where the MUI reconstruction explicitly considers different resampling factors used by different users. Experimental data sets from the 2010 Mobile Acoustic Communications Experiment (MACE10, Martha´s Vineyard, MA) and the 2008 Surface Processes and Acoustic Communications Experiment (SPACE08) are used to emulate a distributed OFDM system with different numbers of users and different numbers of data streams per user. Performance results in different settings validate the effectiveness of the proposed iterative receivers.