Mobile terminal apparatus and system selecting method

• US 20030069037A1
• Filed: 09/12/2002
• Published: 04/10/2003
• Est. Priority Date: 10/05/2001
• Status: Active Grant

• Current Assignee: Fujitsu Mobile Communications Limited (Fujitsu Limited)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ishikura, Akira, Kiyomoto, Moriaki, Sakagawa, Takashi
• Granted Patent: US 7,003,315 B2
• Time in Patent Office: Days
• US Class Current: 455/552.1
• CPC Class Codes: H04W 60/04 using triggered events

Abstract

In a first standby state, the reception quality of a signal from a system which has established synchronization is detected. If the detected reception quality deteriorates to be less than a threshold value, the destination of synchronization establishment is changed from a first system to a second system. In a second standby state after this system change, the reception quality of a system having a higher priority order of selection than the second system which has established synchronization is detected. If a third system whose detected reception quality exceeds the threshold value is found, the destination of synchronization establishment is changed to this third system again. After that, the first standby state is returned.

Claims

1. A mobile terminal apparatus capable of connecting to a plurality of mobile communication systems having different communication standards, comprising:

a system acquiring section configured to acquire a first system from said plurality of mobile communication systems, and proceed to a first standby state;

a first determination section configured to, in the first standby state, detect the reception quality of a signal transmitted from said first system, and check whether the detected reception quality satisfies a first condition; and

a first system reacquiring section configured to, if said first determination section determines that the detected reception quality does not satisfy the first condition, acquire from said plurality of mobile communication systems a second system whose reception quality satisfies a second condition, and proceed to a second standby state.

2. An apparatus according to claim 1, further comprising:

a second determination section configured to, in the second standby state, detect the reception quality of a signal transmitted from a system except for said second system, and check whether there is a third system whose detected reception quality satisfies a third condition; and

a second system reacquiring section configured to, if said second determination section determines that there is the third system whose detected reception quality satisfies the third condition, acquire said system meeting the third condition and return to the first standby state.

3. An apparatus according to claim 2, wherein if said first system is included in the third system meeting the third condition, said second system reacquiring section acquires said first system and returns to the first standby state.

4. A mobile terminal apparatus capable of connecting to a plurality of mobile communication systems having different communication standards, comprising:

a memory configured to store priority orders of selection predetermined for said plurality of mobile communication systems;

a system acquiring section configured to select a first system from said plurality of mobile communication systems on the basis of the priority orders of selection stored in said memory, acquire a base station which belongs to said selected first system, and proceed to a first standby state;

a first determination section configured to, in the first standby state, detect the reception quality of a signal transmitted from said acquired base station, and check whether the detected first reception quality satisfies a first determination condition;

a detection section configured to detect the reception quality of a signal transmitted from a base station which belongs to a system, except for said first system, of said plurality of mobile communication systems;

a first system reacquiring section configured to, if said first determination section determines that the detected first reception quality does not satisfy the first determination condition, select from other mobile communication systems a second system whose second reception quality detected by said detection section is higher than the first reception quality detected by said first determination section, acquire a base station which belongs to said selected second system, and proceed to a second standby state.

5. An apparatus according to claim 4, further comprising:

a second determination section configured to, in the second standby state, detect a reception quality of a signal transmitted from a base station which belongs to a system except for said second system to which said acquired base station belongs, and check whether the detected third reception quality satisfies a second determination condition;

a third determination section configured to check, on the basis of the priority orders of selection stored in said memory and the determination result from said second determination section, whether there is a third system which has a higher priority order of selection than said second system and in which the detected third reception quality satisfies the second determination condition; and

a second system reacquiring section configured to, if said third determination section determines that there is the third system, acquire a base station which belongs to said third system and return to the first standby state.

6. An apparatus according to claim 5, wherein if said second determination section detects a plurality of third systems, said second system reacquiring section selects a system having the highest priority order of selection from said plurality of third systems, acquires a base station which belongs to said selected system, and returns to the first standby state.

7. An apparatus according to claim 5, wherein

said first determination section detects the reception quality of the signal transmitted from the acquired base station of said first system, and checks whether the detected reception quality falls below a first threshold value;

and

said second determination section detects the reception quality of the signal transmitted from the base station which belongs to the system except for said second system to which said acquired base station belongs, and checks whether the detected third reception quality exceeds a second threshold value larger than the first threshold value.

8. An apparatus according to claim 4, wherein

said first determination section detects the reception quality of the signal transmitted from the acquired base station which belongs to said first system a plurality of times at a predetermined time interval, and checks whether the detected reception quality fails to satisfy the first determination condition a preset number of times in succession, and

said first system reacquiring section selects said second system if said first determination section determines that the detected reception quality fails to satisfy the first determination condition the preset number of times in succession.

9. An apparatus according to claim 5, wherein

said second determination section detects, a plurality of times at a predetermined time interval, the reception quality of the signal transmitted from the base station which belongs to the system except for said second system to which said acquired base station belongs, and checks whether the detected third reception quality satisfies the second determination condition a preset number of times in succession, and

said third determination section checks whether there is a third system which has a higher priority order of selection than said second system and in which the detected third reception quality satisfies the second determination condition the preset number of times in succession.

10. An apparatus according to claim 5, wherein said first and second determination sections detect, as the reception quality, the received field strength of a received signal and the ratio (Ec/Io) of the energy (Ec) of a signal received from a base station to be detected to the total energy (Io) of received signals, respectively, and compare the detected received field strength and Ec/Io with different threshold values to check whether both the received field strength and Ec/Io are not less than the threshold values.

11. A mobile terminal apparatus capable of connecting to a first mobile communication system using a digital communication system and a second mobile communication system using an analog communication system, comprising:

a system acquiring section configured to select said first mobile communication system if said first mobile communication system is given a higher priority order of selection than said second mobile communication system, capture a base station which belongs to said first mobile communication system, and proceed to a first standby state;

a first determination section configured to, in the first standby state, detect the reception quality of a signal transmitted from said acquired base station, and check whether the detected reception quality satisfies a first determination condition;

a detection section configured to detect the reception quality of a signal transmitted from a base station which belongs to said second mobile communication system if the first reception quality detected by said first determination section does not satisfy the first determination condition;

a first system reacquiring section configured to acquire a base station which belongs to said second mobile communication system and proceed to a second standby state if the reception quality detected by said detection section is higher than the reception quality detected by said first determination section;

a second determination section configured to, in the second standby state, detect the reception quality of a signal transmitted from a base station which belongs to said first mobile communication system, and check whether the detected reception quality satisfies a second determination condition; and

a second system reacquiring section configured to acquire a base station which belongs to said first system and return to the first standby state if said second determination section determines that the detected reception quality satisfies the second determination condition.

12. A system selecting method used in a mobile terminal apparatus capable of connecting to a plurality of mobile communication systems having different communication standards, comprising:

acquiring a first system from the plurality of mobile communication systems, and proceeding to a first standby state;

detecting the reception quality of a signal transmitted from the first system in the first standby state;

checking whether the detected reception quality satisfies a first condition; and

if it is determined that the detected reception quality does not satisfy the first condition, acquiring from the plurality of mobile communication systems a second system whose reception quality satisfies a second condition, and proceeding to a second standby state.

13. A method according to claim 12, further comprising:

detecting the reception quality of a signal transmitted from a system except for the second system in the second standby state;

checking whether there is a third system whose detected reception quality satisfies a third condition; and

if it is determined that there is the third system whose detected reception quality satisfies the third condition, acquiring the third system meeting the third condition and returning to the first standby state.

14. A method according to claim 13, further comprising, when returning to the first standby state, checking whether the first system is included in the third system meeting the third condition, and acquiring the first system if the first system is included.

15. A system selecting method used in a mobile terminal apparatus capable of connecting to a plurality of mobile communication systems having different communication standards, comprising:

selecting a first system from the plurality of mobile communication systems, acquiring a base station which belongs to the selected first system, and proceeding to a first standby state;

in the first standby state, detecting the reception quality of a signal transmitted from the acquired base station, and checking whether the detected reception quality satisfies a first determination condition;

detecting the reception quality of a signal transmitted from a base station which belongs to a system, except for the first system, of the plurality of mobile communication systems;

if it is determined that the reception quality of the signal transmitted from the base station of the first system does not satisfy the first determination condition, selecting from other mobile communication systems a second system whose reception quality is higher than the reception quality of the signal transmitted from the base station of the first system; and

acquiring a base station which belongs to the selected second system and proceeding to a second standby state.

16. A method according to claim 15, further comprising:

in the second standby state, detecting the reception quality of a signal transmitted from a base station which belongs to a system except for the second system, and checking whether the detected reception quality satisfies a second determination condition;

checking whether there is a third system which has a higher priority order of selection than the second system and in which the detected reception quality satisfies the second determination condition; and

if it is determined that there is the third system, acquiring a base station which belongs to the third system and returning to the first standby state.

17. A method according to claim 16, further comprising, when returning to the first standby state, selecting a system having the highest priority order of selection from the third system meeting the second condition, and acquiring a base station which belongs to the selected system.

18. A system selecting method used in a mobile terminal apparatus capable of connecting to a first mobile communication system using a digital communication system and a second mobile communication system using an analog communication system, comprising:

selecting the first mobile communication system if the first mobile communication system is given a higher priority order of selection than the second mobile communication system, capturing a base station which belongs to the first mobile communication system, and proceeding to a first standby state;

in the first standby state, detecting the reception quality of a signal transmitted from the base station of the first system, and checking whether the detected reception quality satisfies a first determination condition;

detecting the reception quality of a signal transmitted from a base station which belongs to the second mobile communication system if it is determined that the detected first reception quality does not satisfy the first determination condition;

acquiring a base station which belongs to the second mobile communication system and proceeding to a second standby state if the reception quality of the signal transmitted from the base station which belongs to the second mobile communication system is higher than the reception quality of the signal transmitted from the base station of the first system;

in the second standby state, detecting the reception quality of a signal transmitted from a base station which belongs to the first mobile communication system, and checking whether the detected reception quality satisfies a second determination condition; and

if it is determined that the reception quality of the signal transmitted from the base station which belongs to the first mobile communication system satisfies the second determination condition, acquiring the base station which belongs to the first system and returning to the first standby state.