On CDMA transmission over mismatched fading channels employing MMSE-receivers and successive cancellation

A closed solution to the capacity of synchronous CDMA for fading channels supposing exact channel knowledge at the receiver and infinite spreading factor, i.e., N→∞ has been derived by Shamai and Verdu (see IEEE Trans. on IT, 1999). On the other hand, considering imperfect channel state information Evans and Tse (see IEEE Trans. on IT, 1999) derived analytical solutions to the signal to noise ratio provided by linear multiuser receivers and could also give results for the error variance resulting from linear channel estimation. Here, lower and upper bounds on the users SIR reachable by means of a nonlinear MMSE-receiver applying successive cancellation while assuming a certain channel estimation accuracy are given. Note that due to imperfect channel estimation the interference from previously decoded users cannot be cancelled completely even if no decoding errors occur