초록 ▼

A hard handoff method between asynchronous CDMA (code division multiple access) system and synchronous CDMA system is provided. A hard handoff method between asynchronous CDMA (code division multiple access) system and synchronous CDMA system in accordance with an embodiment of the present inventio

A hard handoff method between asynchronous CDMA (code division multiple access) system and synchronous CDMA system is provided. A hard handoff method between asynchronous CDMA (code division multiple access) system and synchronous CDMA system in accordance with an embodiment of the present invention includes following steps. First step is to transmit asynchronous CDMA channels from synchronous CDMA base stations with a purpose of synchronizing handoff time at synchronous CDMA base station and code used at synchronous CDMA base station. The transmission is done by a mobile terminal that is in communication with an asynchronous CDMA base station. The transmission is a part of handoff process and the mobile terminal performs hard handoff to synchronous CDMA base station. Second step is to report measured result to the asynchronous CDMA base station on the basis of intensity of asynchronous CDMA pilot channel received from an adjacent synchronous CDMA base station. The reporting is done by the mobile terminal. Third step is to transmit handoff request message to the synchronous CDMA base station on the basis of the measured result. The transmission is done by the asynchronous CDMA base station. Fourth step is to transmit information necessary for handoff to the asynchronous CDMA base station. The transmission is done by the synchronous CDMA base station that receives the handoff request message. Fifth step is to perform hard handoff to the synchronous CDMA base station. The hard handoff is performed by the mobile terminal that receives the information through a traffic channel from the asynchronous CDMA base station.

대표청구항 ▼

We claim: 1. A hard handoff method from an asynchronous CDMA base station to a synchronous CDMA base station, comprising: a first step of, at the synchronous CDMA base station, transmitting asynchronous CDMA channels including an asynchronous CDMA synchronization channel and an asynchronous CDMA co

We claim: 1. A hard handoff method from an asynchronous CDMA base station to a synchronous CDMA base station, comprising: a first step of, at the synchronous CDMA base station, transmitting asynchronous CDMA channels including an asynchronous CDMA synchronization channel and an asynchronous CDMA common pilot channel to a mobile terminal communicated with the asynchronous CDMA base station for synchronizing a handoff time at the synchronous CDMA base station, wherein the synchronous CDMA base station further transmits synchronous CDMA channels to another mobile terminal; a second step of, at the mobile terminal, measuring each intensity of the asynchronous CDMA common pilot channels outputted from the synchronous CDMA base station and the asynchronous CDMA base station to report the measured result to the asynchronous CDMA base station; a third step of, at the asynchronous CDMA base station, transmitting a handoff request message to the synchronous CDMA base station on the basis of the result reported from the mobile terminal; a fourth step of, at the synchronous CDMA base station which receives the handoff request message, transmitting an information to the asynchronous CDMA base station, wherein the information is necessary to perform the hard handoff; and a fifth step of, at the mobile terminal, performing the hard handoff from the asynchronous CDMA base station to the synchronous CDMA base station in response to the information received from the asynchronous CDMA base station through a traffic channel. 2. The hard handoff method of claim 1, wherein the first step comprises: transmitting the asynchronous CDMA synchronization channel and the asynchronous CDMA common pilot channel; and synchronizing the asynchronous CDMA synchronization channel and the asynchronous CDMA common pilot channel with a starting point of a synchronous pilot channel transmitted from the synchronous CDMA base station. 3. The hard handoff method of claim 1, wherein the second step comprises: measuring an intensity of signals received from the asynchronous CDMA base station and the synchronous CDMA base station using the asynchronous CDMA synchronization channel and the asynchronous CDMA common pilot channel; reporting the intensity of signals and an information regarding the synchronous CDMA base station if the intensity of signals received from the synchronous CDMA base station is bigger than an intensity of signals received from the asynchronous CDMA base station by a predetermined value; and returning to the measuring step if the intensity of signals received from the synchronous CDMA base station is not bigger than the intensity of signals received from the asynchronous CDMA base station by the predetermined value. 4. The hard handoff method of claim 1, wherein the information necessary to perform the handoff includes a starting point of the hard handoff, a long code state at the starting point of the hard handoff, an offset index of a pilot PN (pseudo noise) sequence, a code channel index used in a forward traffic channel, and an offset value regarding the traffic channel. 5. The hard handoff method of claim 1, wherein the fifth step comprises: receiving the information from the asynchronous CDMA base station through the traffic channel; releasing the traffic channel established with the asynchronous CDMA base station and establishing a traffic channel with the synchronous CDMA base station; exchanging an available frame between the mobile terminal and the synchronous CDMA base station through the established traffic channel and confirming a handoff completion; and releasing resources between the asynchronous CDMA base station and a switch, the synchronous CDMA base station reporting the handoff completion to the switch. 6. The hard handoff method of claim 5, wherein the traffic channel between the mobile terminal and the synchronous CDMA base station is established using the starting point of the hard handoff, the long code state at the starting point of the hard handoff, the offset index of the pilot PN sequence, the code channel index used in the forward traffic channel, and the offset value regarding the traffic channel. 7. The hard handoff method of claim 6, wherein the starting point of the hard handoff is determined by calculating how many frames of the common pilot channel have passed at the asynchronous CDMA base station from the moment when the mobile terminal receives the information. 8. A mobile terminal capable of performing a hard handoff from an asynchronous CDMA base station to a synchronous CDMA base station, comprising: circuit configured to receive asynchronous CDMA channels including an asynchronous CDMA synchronization channel and an asynchronous CDMA common pilot channel from the synchronous CDMA base station, while being in communication with the asynchronous CDMA base station; circuit configured to report a measured result to the asynchronous CDMA base station on the basis of each intensity of the asynchronous CDMA channels received from the synchronous CDMA base station and the asynchronous CDMA base station, wherein the measured result is used in order for the asynchronous CDMA base station to transmit a handoff request message to the synchronous CDMA base station which subsequently transmits a handoff information to the asynchronous CDMA base station; and circuit configured to perform the hard handoff to the synchronous CDMA base station by using the handoff information which is received from the asynchronous CDMA base station through a traffic channel. 9. In a dual mode mobile terminal which selectively operates in a synchronous CDMA or an asynchronous CDMA, a hard handoff method from an asynchronous CDMA base station to a synchronous CDMA base station, comprising: measuring an intensity of an asynchronous CDMA common pilot signal generated from the synchronous CDMA base station to be handed off and an intensity of an asynchronous common pilot signal generated from the communicated with asynchronous CDMA base station; and sending the measured intensity of the asynchronous CDMA common pilot channel to an asynchronous CDMA base station that is in communication with the mobile terminal for deciding a handoff to the synchronous CDMA base station. 10. A CDMA telecommunication system having synchronous and asynchronous systems, the CDMA telecommunication system comprising: an asynchronous CDMA base station operating in a 3G asynchronous CDMA network; and a synchronous CDMA base station operating in a 2G asynchronous CDMA network, wherein the synchronous CDMA base station; a) transmits asynchronous CDMA channels including an asynchronous CDMA synchronization channel and an asynchronous CDMA common pilot channel to the mobile terminal communicated with the asynchronous CDMA base station for synchronizing a handoff time at the synchronous CDMA base station, wherein the synchronous CDMA base station further transmits synchronous CDMA channels to other mobile terminal; and b) transmits an information to the asynchronous CDMA base station when the synchronous CDMA base station which receives the handoff request message from the asynchronous CDMA base station. 11. A synchronous CDMA base station operating in a 2G asynchronous CDMA network, wherein the synchronous CDMA base station: a) transmits asynchronous CDMA channels including an asynchronous CDMA synchronization channel and an asynchronous CDMA common pilot channel to the mobile terminal communicated with the asynchronous CDMA base station for synchronizing a handoff time at the synchronous CDMA base station, wherein the synchronous CDMA base station further transmits synchronous CDMA channels to other mobile terminal; and b) transmits an information to an asynchronous CDMA base station when the synchronous CDMA base station which receives a handoff request message from the asynchronous CDMA base station.