Packet switched radio telecommunication system supporting hard handover and method for hard handover

1. A packet switched radio telecommunication system, comprising:

a support packet data serving node (PDSN) to assign a temporary Internet Protocol (IP) address to a mobile terminal in its service area, to maintain a direct link to a neighboring PDSN, and to transmit handover data and the temporary IP address assigned by the support PDSN to the neighboring PDSN via the direct link; and

a target PDSN to register the temporary IP address in an IP pool in response to a request from the mobile terminal moved into a service area of the target PDSN,

wherein the target PDSN receives down-link frame data from the support PDSN via the direct link, the down-link frame data being transmitted to the mobile terminal at the temporary IP address, and

wherein the neighboring PDSN is the target PDSN, and the target PDSN compares a temporary IP address identified by the mobile terminal with the temporary IP address transmitted from the support PDSN, and if they are identical, registers the temporary IP address in the IP pool.

2. The packet switched radio telecommunication system of claim 1 , wherein the mobile terminal gives back the temporary IP address to the support PDSN after moving to the service area of the target PDSN, and is assigned with a new temporary IP address corresponding to an IP address from the IP pool.

3. The packet switched radio telecommunication system of claim 2 , wherein the mobile terminal gives back the temporary IP address to the support PDSN after data transmission or reception is complete.

4. The packet switched radio telecommunication system of claim 2 , wherein the mobile terminal gives back the temporary IP address to the support PDSN if the mobile terminal enters a dormant state.

5. A method for handing over a mobile terminal from a support packet data serving node (PDSN) to a target PDSN, the method comprising:

assigning a temporary IP address to the mobile terminal in a service area of the support PDSN;

configuring a direct link between the support PDSN and the target PDSN and maintaining a protocol configuration;

transmitting handover data and a temporary IP address of the mobile terminal from the support PDSN to the target PDSN via the direct link;

requesting registration of the temporary IP address to the target PDSN;

registering the temporary IP address of the mobile terminal in an IP pool of the target PDSN;

transmitting down-link frame data transmitted from a core network from the support PDSN to the target PDSN via the direct link; and

transmitting the down-link frame data to the mobile terminal in a service area of the target PDSN at the temporary IP address,

wherein registering the temporary IP address comprises comparing by the target PDSN a temporary IP address identified by the mobile terminal with the temporary IP address transmitted from the support PDSN, and registering the temporary IP address in the IP pool of the target PDSN if they are identical.

6. The method of claim 5 , further comprising:

giving back the temporary IP address to the support PDSN; and

assigning the mobile terminal with a new temporary IP address through a Point to Point Protocol (PPP) connection to the target PDSN, and registering the new temporary IP address in the core network.

7. The method of claim 6 , wherein the core network comprises a home agent of the mobile terminal.

8. The method of claim 6 , wherein the new temporary IP address corresponds to an IP address from an IP pool in the target PDSN.

9. The method of claim 6 , wherein the mobile terminal gives back the temporary IP address to the support PDSN after data transmission or reception is complete at the mobile terminal.

10. The method of claim 6 , wherein the mobile terminal gives back the temporary IP address to the support PDSN if the mobile terminal enters a dormant state.