MMSE-based groupwise successive interference cancellation scheme for multirate CDMA systems

In this work, group-wise successive interference cancellation (GSIC) scheme for multi-rate CDMA systems is proposed. A multi-rate CDMA system is a CDMA system that can support voice users together with data users which may have different data rates. In the proposed group-wise detection, users with the same information rate are grouped and detected together. Users with the highest information rate are detected first, neglecting the presence of the other users in the system. Interference between the groups is cancelled in a successive order. The proposed scheme is based on the minimum mean square error (MMSE) criterion. We also studied the decision feedback interference cancellation for multi-rate CDMA systems. The performance of the proposed detection scheme is compared with that of conventional detector, the decorrelating detector, and the linear MMSE detector for multi-rate CDMA systems. The proposed scheme achieves better performance than the above-mentioned detectors. The proposed scheme also provides significantly high spectral efficiency under certain conditions. The algorithms in the proposed scheme are suitable for both terrestrial and satellite applications of multi-rate CDMA systems.