A new RAKE receiver structure for the forward-link of W-CDMA systems

We propose a new receiver structure to mitigate interpath interference (IPI) in W-CDMA systems. We model IPI in RAKE combining as intersymbol interference (ISI) and use a two-stage receiver structure. The first stage is a RAKE receiver and the second stage is an equalizer. In cases of multicode transmission; interference among code channels causes extra impairments which can not be modelled as ISI. Under these circumstances, they are estimated by using decisions from the first stage and then subtracted from the input of the equalizer. The residual interference is equivalent to ISI and can be mitigated by the equalizer. Simulation results show that the proposed receiver provides very promising performance in low spreading factor WC CDMA.