Iterative MMSE Detection and Interference Cancellation for Uplink SC-FDMA MIMO Using HARQ
For high-speed packet access, Hybrid Automatic Repeat reQuest (HARQ) and Multiple-Input Multiple-Output (MIMO) multiplexing are indispensable techniques. As the multiple-access technique, Single Carrier (SC)-Frequency-Division Multiple-Access (FDMA) using transmit filtering is promising. The use of square-root Nyquist transmit filter reduces Peak-to-Average Power Ratio (PAPR) of the transmit SC-FDMA signal and increases the frequency diversity gain. However, if the carrier-frequency separation among multiple-access users is kept the same as in the case of the transmit filter's roll-off factor ?=0 (i.e., brick wall filter), the adjacent users' signal spectra overlap and the Multi-User Interference (MUI) is produced.