To support multiple Service class of different datatransmission rate for multimedia application in wirelesssystems. WCDMA involves orthogonal variable spreadingfactor (OVSF) code technique. Call admission control(CAC) scheme of the system decides regarding admissionof the call. In this paper a new SIR- based CAC schemefor WCDMA system is proposed, so that we can controlaccess of available resource for each service class. A newcall request in the system will be accepted, based on the availability of the codes. CDMA system W-CDMA system suffers from code blocking problem to accommodate high data rate calls. This problem can be eliminated by code reassignment technique, finally Markov analysis is used to evaluate the performance of the proposed scheme, considering blocking probability of hand off and new callas performance measure.