Unified spatio-temporal frequency domain equalization for multi- and single-carrier CDMA systems
Lars Brühl, Bernhard Rembold · 2003
Single carrier (SC-) and multi carrier (MC-) CDMA transmission are compared. Spreading and pulse shaping processes are shown to be identical in both systems. Based on this equality, a unified frequency domain system model is derived for a multiuser system with multiple base station antennas. The system model includes the effects of spreading, oversampling, pulse shaping, the MIMO (multiple input multiple output) channel and selection filter. Linear spatio-temporal joint detection is proposed for the uplink and an appropriate predistortion for the downlink. Predistortion offers efficient downlink transmission with spatial diversity and uses a signal processing very similar to the joint detection. Similarities of uplink and downlink processing of SC and MC-CDMA argues for a unified hardware implementation. This idea is discussed and some implementation issues like variable FFT sizes, conflicts in resource sharing, different resolution requirements and computational complexity are addressed.