Advanced transceiver Architectures for downlink MIMO CDMA evolution

This paper investigates the combination of spatial multiplexing and overloading as an evolution of the UMTS-HSDPA (High Speed Downlink Packet Access) toward very high spectral efficiencies in the case of no (or very limited) channel. state information at transmitter. Overloaded spreading is carried out in the time domain only (independent per antenna), transmit space diversity is partially recovered employing Space-Time BICM for each user. A low complexity soft interference cancellation based iterative receiver for channel estimation, space-time chip-equalization and multiuser detection is proposed. Two scenarios are considered for the intracell interference: either the spreading codes and the modulation of the interfering users are known or no-knowledge of the interfering signals is available at the receiver whatsoever.