Abstract: In order to solve the problem of multiuser detection(MUD)judgment error diffusion of single successive interference cancellation(SIC)and parallel interference cancellation(PIC)algorithm，the interference cancellation algorithm of direct sequence spread spectrum code division multiple access(DSCDMA)system was studied under condition of strong multiple access interference(MAI). A KAIC cascade structure algorithm which combined with adaptive Kalman algorithm was proposed for the fading channel. The timevarying channel could be fully tracked by the proposed algorithm， and the detection error diffusion in detection process was able to be avoided. In addition， the purpose of MAI suppression was achieved. Simulation results showed that the proposed algorithm is of better convergence， dynamic tracking ability and algorithm precision， therefore， it is an effective interference cancellation MUD algorithm.

Key words: CDMA(code division multiple access), SIC(successive interference cancellation), PIC(parallel interference cancellation), MUD(multiuser detection), Kalman filter, MAI(multiple access interference)