Patent ID: 7826423

Claim:
A handover method between asynchronous and synchronous mobile communication systems for a Dual Band Dual Mode (DBDM) mobile communication terminal in a mobile communication network in which the asynchronous and synchronous mobile communication systems overlap each other, the mobile communication terminal having an asynchronous modem unit and a synchronous modem unit, comprising: the first step of a radio network controller of the asynchronous mobile communication system periodically measuring a wireless environment around the mobile communication terminal; the second step of the radio network controller determining whether handover is required using a blind decision method when wireless environment measurement values are less than predetermined threshold values, and informing an asynchronous mobile switching center of the asynchronous communication system that the handover is required; the third step of the asynchronous mobile switching center requesting handover from a synchronous mobile switching center of the synchronous communication system, and the synchronous mobile switching center assigning a forward channel to the mobile communication terminal; the fourth step of, as the asynchronous mobile switching center directs the mobile communication terminal to perform handover, the mobile communication terminal preparing communication with the synchronous mobile communication system, and causing a backward channel with respect to the synchronous communication system to be assigned to the mobile communication terminal; and the fifth step of the synchronous mobile switching center informing the asynchronous mobile switching center of completion of the handover, thus releasing a connection between the asynchronous mobile switching center and the radio network controller.