METHOD FOR IMPLEMENTING A VOICE PRIVACY FUNCTION IN HANDOFF IN A CDMA SYSTEM, PARTICULARLY FOR PERFORMING A HANDOFF FUNCTION BETWEEN A VOICE PRIVACY-SUPPORTING BASE STATION AND A BASE STATION NOT SUPPORTING THE VOICE PRIVACY BY PROVIDING A CALL FLOW

摘要

PURPOSE: A method for implementing a voice privacy function in handoff in a CDMA system is provided to perform handoff regardless of whether a base station supports a voice privacy or not and strengthen security of a system. CONSTITUTION: A CCP(Call Control Processor)(500) informs a TSB(Transcoder and Selector Bank)(400) about soft add handoff(S101). Upon receiving a handoff assign message from the CCP(500), the TSB transmits a time synchronous packet to a target BTS(Base Transceiver Subsystem)(300)(S102) and the target BTS(300) responds by a time synchronous packet(S103). The TSB(400) transmits a public request message requesting release of voice privacy to an MS(Mobile Station)(S104). The MS(100) responds by a public response message informing of release of the voice privacy(S105). The TBS(400) transmits a control message requesting release of the voice privacy to a serving BTS(200)(S106). The serving BTS(200) informs the TSB(400) whether or not the voice privacy has been successfully released(S107), Informed that the voice privacy has been successfully released, the TSB(400) transmits a handoff direction message to the MS(100)(S108). The target BTS(300) informs the TSB(400) that the MS has been acquired(S109). The TSB(400) transmits an ACK to the target BTS(300)(S110). The MS(100) informs the TSB(400) that handoff has been successfully completed(S111). The TSB(400) informs the CCP(500) of completion of handoff(S112).