We investigate detection structures for a DS-CDMA. multiuser uplink using codes with a period of several symbols, named long codes. We first propose a multirate description of the uplink. Then based on this formalism we revisit a number of popular receiver structures: RAKE receivers, minimum mean square error linear and decision feedback fractionally spaced detectors.
Vandendorpe, L., Horlin, F., & Sartenaer, T. (2001). FSLE and FSDF joint detectors for long code DS-CDMA. 2001 IEEE International Conference on Acoustics, Speech, and SignalProcessing. Proceedings (Cat. No.01CH37221), Vol. 4, p. 2261-2264. https://doi.org/10.1109/ICASSP.2001.940449