Method and apparatus for reducing the number of times of measurements for cell reselection in mobile communication terminal

• US 20070223510A1
• Filed: 02/06/2007
• Published: 09/27/2007
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Joo, Jung-Hoon
• Granted Patent: US 8,045,989 B2
• Time in Patent Office: Days
• US Class Current: 370/436
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements

Abstract

Provided is a method and apparatus for reducing the number of times of measurements in a mobile communication terminal. According to the method, a signal receive level (“Srxlev”) and a signal quality (“Squal”) of a serving cell in an idle state are measured. When the serving-cell selection condition is not satisfied or an adjacent-cell measurement condition is satisfied as a result of the measurement, it is determined whether the number of times of cell reselections reaches a critical value. When the number of times of cell reselections reaches the critical value, the number of times of cell reselection is initialized to a value smaller than the critical value and the mobile terminal returns to an idle state. When the number of times of cell reselections does not reach the critical value, an adjacent-cell measurement for the cell reselection is performed. Therefore, unnecessary quiescent current consumption is reduced and a quiescent current performance is improved.

Claims

1. A method for reducing a frequency of measurements for cell reselection in a mobile communication terminal, comprising the steps of:

measuring a signal receive level (“

Srxlev”

) and a signal quality (“

Squal”

) of a serving cell in an idle state;

when a serving-cell selection condition is not satisfied or an adjacent-cell measurement condition is satisfied as a result of the measurement, examining whether the number of times of cell reselections reaches a critical value;

when the number of times of cell reselections reaches the critical value, initializing the number of times of cell reselection using a value smaller than the critical value and returning to an idle state; and

when the number of times of cell reselections does not reach the critical value, performing an adjacent-cell measurement for the cell reselection.

2. The method of claim 1, wherein the serving-cell selection condition comprises one of Srxlev>

0 and Squal>

0.

3. The method of claim 1, wherein the adjacent-cell measurement condition comprises adjacent-cell data>

Squal.

4. The method of claim 3, wherein the adjacent-cell data comprises one of relevant cell data for intra frequency measurement, relevant cell data for inter frequency measurement, relevant cell data for inter-radio access technologies (RAT) measurement, and the data are received from a network.

5. The method of claim 4, wherein the adjacent-cell measurement condition further comprises a case where the adjacent-cell data is not received from the network.

6. The method of claim 1, further comprising the steps:

determining a ranking of adjacent cells using a result of the adjacent-cell measurement and determining whether an adjacent cell of a highest ranking is superior to the serving cell;

performing reselection of a corresponding cell and returning to the idle state when the adjacent cell of the highest ranking is the cell superior to the serving cell;

determining that cell reselection has failed and examining whether the cell reselection failure is a successive failure when the adjacent cell of the highest ranking is not the cell superior to the serving cell;

when the cell reselection failure is the successive failure, replacing the number of times of cell reselection by a value obtained by adding 1 to the number of cell reselection, and returning to the idle state; and

when the cell reselection failure is not the successive failure, initializing the number of cell reselection to 0, and returning to the idle state.

7. The method of claim 6, wherein the superiority of the adjacent cell is determined by examining whether the adjacent cell maintains a better state than the serving cell for a predetermined time.

8. A mobile communication terminal for reducing a frequency of measurements for cell reselection comprising:

a controller for measuring a signal receive level (“

Srxlev”

) and a signal quality (“

Squal”

) of a serving cell in an idle state, examining whether the number of times of cell reselections reaches a critical value when a serving-cell selection condition is not satisfied or an adjacent-cell measurement condition is satisfied as a result of the measurement, initializing the number of times of cell reselection using a value smaller than the critical value and returning to an idle state when the number of times of cell reselections reaches the critical value, and performing an adjacent-cell measurement for the cell reselection when the number of times of cell reselections does not reach the critical value.

9. The mobile communication terminal of claim 8, wherein the serving-cell selection condition comprises one of Srxlev>

0 and Squal>

0.

10. The mobile communication terminal of claim 9, wherein the adjacent-cell measurement condition comprises adjacent-cell data>

Squal.

11. The mobile communication terminal of claim 10, wherein the adjacent-cell data comprises one of relevant cell data for intra frequency measurement, relevant cell data for inter frequency measurement, relevant cell data for inter-radio access technologies (RAT) measurement, and the data are received from a network.

12. The mobile communication terminal of claim 11, wherein the adjacent-cell measurement condition further comprises a case where the adjacent-cell data is not received from the network.

13. The mobile communication terminal of claim 8, wherein the controller further performs the steps of determining a ranking of adjacent cells using a result of the adjacent-cell measurement and determining whether an adjacent cell of a highest ranking is superior to the serving cell, performing reselection of a corresponding cell and returning to the idle state when the adjacent cell of the highest ranking is the cell superior to the serving cell, determining that cell reselection has failed and examining whether the cell reselection failure is a successive failure when the adjacent cell of the highest ranking is not the cell superior to the serving cell, replacing the number of times of cell reselection by a value obtained by adding 1 to the number of cell reselection when the cell reselection failure is the successive failure, and returning to the idle state, and initializing the number of cell reselection to 0 when the cell reselection failure is not the successive failure, and returning to the idle state.

14. The mobile communication terminal of claim 13, wherein the superiority of the adjacent cell is determined by examining whether the adjacent cell maintains a better state than the serving cell for a predetermined time.