FDE-RAKE: a PIC multiuser detector for CDMA downlink

The paper introduces a two stage multiuser detector for CDMA downlink systems. Frequency domain equalization (FDE) is used at the first stage as a single-user detector. A RAKE receiver is then employed at the second stage, following a parallel interference cancellation (PIC) process. The performance of the FDE-RAKE detector is evaluated in a UTRA-TDD system, and compared with the linear multiuser detector. The FDE-RAKE demonstrates a slightly better performance than the linear multiuser detector, while retaining the simplicity of the employed algorithm. It also offers the important advantage that the detection quality of the first stage is significantly better than the detection of the RAKE receiver, which is usually used as the first processing stage in most CDMA multiuser detection strategies. Hence, the second stage of the FDE-RAKE detector can be optionally added if better detection is required.