Patent ID: 7242708

Claim:
A method of detecting a spread spectrum composite signal (r) comprising plural user signals (b 1 ,b 2 , . . . ,b K ) that have been spread with spreading codes to minimize multiple access interference, comprising: a) receiving the composite signal (r) at a rake receiver; b) obtaining a rake receiver output z Rake =A H S H r; c) producing first hard-decision values b Rake =sgn(z Rake ) based on the rake receiver output z Rake ; d) producing first parallel interference cancellation values z Rake −Fb Rake based on b Rake ; e) producing second hard-decision values b PIC =sgn(z Rake −Fb Rake ) based on the first parallel interference cancellation values; f) producing first combination values {circumflex over (b)} by combining the hard-decision values b Rake and b PIC ; g) producing second parallel interference cancellation values z Rake −F{circumflex over (b)} based on the first combination values {circumflex over (b)}; and h) producing third hard-decision values {circumflex over (b)} EPIC (1)=sgn(z Rake −F{circumflex over (b)}) based on the second parallel interference cancellation values such that multiple access interference is minimized, said {circumflex over (b)} EPIC (1) being an output of an equalized parallel interference cancellation (EPIC) detector at a first stage; wherein: S=spreading code matrix; A=channel coefficient matrix; ( ) H =conjugate transpose operation; and F=off-diagonal cross-correlation matrix.