Apparatus, system, and methods for handling attach procedure in mobile communication system

1. A user equipment, handling an attach procedure with a service network, comprising:

a wireless module transmitting an attach request message to the service network and receiving an attach accept message replied to the attach request message from the service network; and

a controller determining whether to accept the attach accept message, sending an attach complete message, via the wireless module, to the service network in response to the attach accept message being accepted, and resending the attach request message, via the wireless module, to the service network in response to the attach accept message not being accepted.

2. The user equipment of claim 1 , further comprising a retry counter, wherein the retry counter is initialized to 0 before starting the attach procedure, increased upon resending the attach request message, and reset when the attach procedure ends.

3. The user equipment of claim 2 , wherein the attach request message is resent with a resent cause when the retry counter is less than a predetermined number.

4. The user equipment of claim 3 , wherein the controller further determines whether the retry counter is less than the predetermined number, and sends a detach request message, via the wireless module, to the service network in response of that the retry counter is greater than or equal to the predetermined number.

5. A method for a user equipment to handle an attach procedure with a service network, comprising:

sending an attach request message to the service network;

receiving an attach accept message replied to the attach request message from the service network;

determining whether to accept the attach accept message;

sending an attach complete message to the service network in response to the attach accept message being accepted; and

resending the attach request message to the service network in response to the attach accept message not being accepted.

6. The method of claim 5 , further comprises initializing a retry counter to 0 before starting the attach procedure, increasing the retry counter upon resending the attach request message, and resetting the retry counter when the attach procedure ends.

7. The method of claim 6 , wherein the attach request message is resent with a resent cause when the retry counter is less than a predetermined number.

8. The method of claim 7 , further comprises determining whether the retry counter is less than the predetermined number, and sending a detach message to the service network in response of that the retry counter is greater than or equal to the predetermined number.

9. A service network, handling an attach procedure with a user equipment, comprising:

a radio access network receiving an attach request message from the user equipment, sending a first attach accept message to the user equipment in response to the attach request message, and receiving a response message from the user equipment; and

a control node determining that the attach procedure has ended successfully in response to the response message being an attach complete message, aborting the attach procedure and initiating a new attach procedure by sending a second attach accept message, via the radio access network, to the user equipment in response to the response message being the attach request message resent by the user equipment, and aborting the attach procedure and sending a detach accept message, via the radio access network, to the user equipment in response to the response message being a detach request message.

10. The service network of claim 9 , wherein the attach complete message is sent upon the first attach accept message being accepted by the user equipment.

11. The service network of claim 9 , wherein the attach request message resent by the user equipment is resent with a resent cause upon the first attach accept message not being accepted by the user equipment.

12. The service network of claim 9 , wherein the detach request message is sent, upon the first attach accept message not being accepted by the user equipment and the number of resending the attach request message being greater than or equal to a predetermined number.

13. A method for a service network to handle an attach procedure with a user equipment, comprising:

receiving an attach request message from the user equipment;

sending a first attach accept message to the user equipment in response to the attach request message;

receiving a response message from the user equipment;

determining that the attach procedure has ended successfully in response to the response message being an attach complete message;

aborting the attach procedure and initiating a new attach procedure by sending a second attach accept message to the user equipment in response to the response message being the attach request message resent by the user equipment; and

aborting the attach procedure and sending a detach accept message to the user equipment in response to the response message being a detach request message.

14. The method of claim 13 , wherein the attach complete message is sent upon the first attach accept message being accepted by the user equipment.

15. The method of claim 13 , wherein the attach request message resent by the user equipment is resent with a resent cause upon the first attach accept message not being accepted by the user equipment.

16. The method of claim 13 , wherein the detach request message is sent, upon the first attach accept message not being accepted by the user equipment and the number of resending the attach request message being greater than or equal to a predetermined number.

17. A mobile communication system, handling an attach procedure, comprising:

a user equipment sending an attach request message, receiving a first attach accept message replied to the attach request message, determining whether to accept the first attach accept message, sending an attach complete message in response to the first attach accept message being accepted, and resending the attach request message in response to the first attach accept message not being accepted; and

a service network receiving the attach request message, sending the first attach accept message to the user equipment in response to the attach request message, determining that the attach procedure has ended successfully upon receiving the attach complete message, and aborting the attach procedure and initiating a new attach procedure by sending a second attach accept message to the user equipment upon receiving the attach request message resent by the user equipment.

18. The mobile communication system of claim 17 , wherein the attach request message resent by the user equipment is resent with a resent cause when the number of resending the attach request message is less than a predetermined number.

19. The mobile communication system of claim 18 , wherein the user equipment further determines whether the number of resending the attach request message is less than the predetermined number, and sends a detach request message to the service network in response of that the number of resending the attach request message is greater than or equal to the predetermined number.

20. The mobile communication system of claim 19 , wherein the service network further aborts the attach procedure and sends a detach accept message to the user equipment upon receiving the detach request message.