Low-Complexity Realization of a Concatenated DMT–FMT Multiuser Uplink System With Transmit Diversity

We present an efficient realization of a novel wireless uplink transmission scheme. The scheme concatenates an inner filtered multitone (FMT) modulator with transmission over multiple antennas and an outer space-time cyclically prefixed discrete multitone (DMT) modulator. The inner modulator is used to realize frequency-division multiplexing of the users by partitioning the FMT subchannels among them. The outer modulator copes with the residual subchannel intersymbol interference, and it further implements a form of transmit diversity. Frequency and space diversity is exploited via direct-sequence data spreading across the DMT tones. We also propose a multiuser analysis filter bank that significantly lowers the receiver complexity.