Multiuser decision-feedback receivers for asynchronous CDMA systems over a mismatched flat Rayleigh fading channel

In this paper, the design of decision-feedback multiuser (DFM) receivers for asynchronous code-division multiple-access (CDMA) systems over a mismatched flat Rayleigh fading channel is studied, and tight upper and lower bounds on the pairwise symbol-error probability, which has been averaged over the channel fading, time delays, and phase angles, are derived for some of the DFM detection schemes. The performance bounds, which are computed by efficient analytic techniques, can serve as reliable references for CDMA system design. It is shown that the proposed system, which takes into account the effect of mismatched fading on the system design, has some gain over the system where the estimation of fading is assumed to be exact.