Method of providing packet data service

1 . A method for providing a packet data service, comprising:

receiving a request message for a session connection from a mobile terminal;

deciding presence or non-presence of a validity of the request message for the session connection; and

transferring a connection deny message or allocating a traffic channel according to a result of the deciding step.

2 . The method of claim 1 , wherein the connection deny message is transferred when non-presence of the validity is decided.

3 . The method of claim 1 , further comprising:

assigning a terminal identifier to a mobile terminal, said assigning including:

receiving a terminal identifier request message;

generating a timestamp; and

transferring the timestamp to the mobile terminal.

4 . The method of claim 3 , further comprising:

receiving a terminal identifier assignment complete message.

5 . The method of claim 3 , wherein the request message for the session connection includes the terminal identifier and the timestamp therein.

6 . The method of claim 5 , wherein the timestamp includes a system time of the network at a time point of assigning the user identifier.

7 . The method of claim 1 , wherein in the deciding step, an access network compares a stored timestamp to a timestamp included in the request message to decide the presence of the validity if the stored timestamp is identical to the timestamp included in the request message.

8 . The method of claim 1 , wherein the connection deny message includes a DenyReason field indicating ‘unsuitable session’.

9 . The method of claim 1 , wherein the network and the mobile terminal are an access network and an access terminal, respectively.

10 . A method for providing a packet data service, comprising:

transferring a session close message from a mobile terminal to a network;

deciding presence or non-presence of a validity of the session close message; and

maintaining or releasing session information according to a result of the deciding step.

11 . The method of claim 10 , wherein the transferred session close message includes a terminal identifier and a timestamp therein.

12 . The method of claim 11 , the deciding step comprises:

comparing a timestamp stored in the network to the timestamp included in the session close message; and

deciding the presence of the validity if the stored timestamp is identical to the timestamp included in the session close message.

13 . The packet data service providing method of claim 10 , wherein if the session close message is valid as a result of the deciding step, a session is closed.

14 . The method of claim 13 , further comprising:

transferring the session close message to the mobile terminal.

15 . The method of claim 10 , wherein the network and the mobile terminal are an access network and an access terminal, respectively.

16 . A method for providing a packet data service, comprising:

requesting a terminal identifier assignment to a network;

receiving the terminal identifier and a timestamp from the network;

transferring a connection request message including the terminal identifier and the timestamp to the network;

allocating a connection deny message or a traffic channel according to a validity test result from the network; and

releasing session information if the terminal receives the connection deny message.

17 . The method of claim 16 , wherein the timestamp is a system time of the network at a time point of assigning the user identifier.

18 . A method for providing a packet data service, comprising:

transferring a first session close message including a terminal identifier and a timestamp to a network;

receiving a second session close message according to a validity test result of the first session close message in the network; and

closing a session information if the second session close message is received.

19 . The method of claim 18 , wherein the validity test result is decided by:

comparing a timestamp stored in the network to the timestamp included in the first session close message: and

deciding a presence of validity if the stored timestamp is identical to the timestamp included in the first session close message.

20 . A method for providing a packet data service, comprising:

requesting a terminal identifier assignment to a network;

transferring the terminal identifier and a timestamp to a mobile terminal;

transferring a connection request message including the terminal identifier and the timestamp to the network;

checking a validity of a corresponding connection request in the network; and

transferring a connection deny message or allocating a traffic channel according to a result of the checking step.