Method and mobile terminal for searching home network

1. A method for searching for a home network for a mobile terminal, the method comprising:

performing a full scan for searching for the home network at a certain time after roaming to a visited network;

initializing a count of a number of times a timer has expired when the home network is not found;

initiating the timer;

updating the count when the timer expires;

scanning frequencies included in a frequency list comprising at least one of an Acquisition Database list previously stored in a storage unit of the mobile terminal and a Higher Priority Public Land Mobile Network list previously stored in a Subscriber Identity Module (SIM) card when the count is less than a certain value; and

scanning all frequencies around the mobile terminal when the count is equal to the certain value.

2. The method of claim 1 , wherein the scanning of the frequencies included in the frequency list comprises:

camping on the home network when the home network is found; and

reinitiating the timer when the home network is not found.

3. The method of claim 1 , wherein the scanning of all the frequencies around the mobile terminal comprises:

camping on the home network when the home network is found; and

initializing the count when the home network is not found.

4. The method of claim 1 , wherein the Acquisition Database stores information related to Public Land Mobile Networks and frequencies of the Public Land Mobile Networks.

5. The method of claim 1 , wherein the updated count is stored in a buffer.

6. A method for searching for a home network for a mobile terminal, the method comprising:

performing a full scan for searching for the home network at a certain time after roaming to a visited network;

initiating a first timer set to a first search interval and a second timer set to a second search interval when the home network is not found;

scanning frequencies included in a frequency list comprising at least one of an Acquisition Database list previously stored in a storage unit of the mobile terminal and a Higher Priority Public Land Mobile Network list previously stored in a Subscriber Identity Module (SIM) card when the first timer expires; and

scanning all frequencies around the mobile terminal when the second timer expires.

7. The method of claim 6 , wherein the scanning of the frequencies included in the frequency list comprises:

camping on the home network when the home network is found; and

reinitiating the first timer when the home network is not found.

8. The method of claim 6 , wherein the scanning of all the frequencies around the mobile terminal comprises:

camping on the home network when the home network is found; and

reinitiating the first timer and the second timer when the home network is not found.

9. The method of claim 6 , wherein the Acquisition Database stores information related to Public Land Mobile Networks and frequencies of the Public Land Mobile Networks.

10. The method of claim 6 , wherein the second search interval is N multiples of the first search interval, wherein N is a natural number.

11. A mobile terminal comprising:

a radio frequency unit for establishing a communication channel;

a timer for defining an interval for scanning frequencies included in a frequency list comprising at least one of an Acquisition Database list previously stored in a storage unit of the mobile terminal and a Higher Priority Public Land Mobile Network list previously stored in a Subscriber Identity Module (SIM) card;

a control unit for performing a full scan for searching for a home network at a certain time after roaming to a visited network, for initializing a count of a number of times a timer has expired when the home network is not found, for initiating the timer, for updating the count when the timer expires, for scanning frequencies included in the frequency list when the count is less than a certain value, and for scanning all frequencies around the mobile terminal when the count is equal to the certain value; and

a buffer for storing the updated count.

12. The terminal of claim 11 , wherein the control unit controls camping on the home network when the home network is found as a result of the frequencies scanned in the frequency list and reinitiating the timer when the home network is not found as a result of the frequencies scanned in the frequency list.

13. The terminal of claim 11 , wherein the control unit controls camping on the home network when the home network is found as a result of all the frequencies scanned around the mobile terminal and initializing the buffer when the home network is not found as a result of all the frequencies scanned around the mobile terminal.

14. The terminal of claim 11 , wherein the Acquisition Database stores information related to Public Land Mobile Networks and frequencies of the Public Land Mobile Networks.

15. A mobile terminal comprising:

a radio frequency unit for establishing a communication channel;

a first timer set to a first search interval;

a second timer set to a second search interval; and

a control unit for performing a full scan at a certain time after roaming to a visited network, for initiating the first timer and the second timer when the home network is not found, for scanning frequencies included in a frequency list comprising at least one of an Acquisition Database list previously stored in a storage unit of the mobile terminal and a Higher Priority Public Land Mobile Network list previously stored in a Subscriber Identity Module (SIM) card when the first timer expires, and for scanning all frequencies around the mobile terminal when the second timer expires.

16. The terminal of claim 15 , wherein the control unit controls camping on the home network when the home network is found as a result of the frequencies scanned in the frequency list and reinitiating the first timer when the home network is not found as a result of the frequencies scanned in the frequency list.

17. The terminal of claim 15 , wherein the control unit controls camping on the home network when the home network is found as a result of all the frequencies scanned around the mobile terminal and reinitiating the first timer and the second timer when the home network is not found as a result of all the frequencies scanned around the mobile terminal.

18. The mobile terminal of claim 15 , wherein the Acquisition Database stores information on Public Land Mobile Networks and frequencies of the Public Land Mobile Networks.

19. The terminal of claim 15 , wherein the second search interval is N multiples of the first search interval, wherein N is a natural number.