Method for inter-radio access technology cell reselection

• US 9,474,006 B2
• Filed: 03/24/2014
• Issued: 10/18/2016
• Est. Priority Date: 06/18/2007
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Pani, Diana, Sammour, Mohammed, Somasundaram, Shankar, Wang, Jin, Mukherjee, Rajat P.
• Primary Examiner(s): HEIBER, SHANTELL LAKETA
• Application Number:
  US14/223,997
• Publication Number:
  US 20140206355A1
• Time in Patent Office: 939 Days
• US Class Current: 1/1
• CPC Class Codes: H04W 36/00837 Determination of triggering parameters for hand-off
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data

Abstract

A method for performing cell reselection first determines a current cell selection quality value. The cell selection quality value is compared to a predetermined threshold. Measurements of neighboring cells are taken if the cell selection quality value is less than or equal to the predetermined threshold. Measurements can be taken of intra-frequency cells, inter-frequency cells, and inter-radio access technology cells. If a neighboring cell is found that is better than the current cell based on the measurements, then the better neighbor cell is reselected to.

Claims

1. A method for performing cell reselection implemented in a wireless transmit receive unit (WTRU), the method comprising:

receiving priority information in a current cell associated with a current radio access technology (RAT), the priority information indicating a cell priority of an inter-RAT cell associated with a candidate RAT relative to the current cell associated with the current RAT;

determining whether the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT based on the priority information;

determining a cell selection value of the current cell;

determining to perform quality measurements of the inter-RAT cell associated with the candidate RAT on condition that it is determined that the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT; and

determining to perform quality measurements of the inter-RAT cell associated with the candidate RAT on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell in the current RAT and that the cell selection value of the current cell is less than or equal to a predetermined threshold.

2. The method as in claim 1, wherein one of the current cell or the inter-RAT cell is a long term evolution (LTE) cell in an evolved universal terrestrial radio access network (E-UTRAN).

3. The method as in claim 1, wherein the priority information includes frequency information for the inter-RAT cell.

4. The method as in claim 1, further comprising reselecting to the inter-RAT cell based on the quality measurement.

5. The method as in claim 1, further comprising:

reselecting to the inter-RAT cell based on a signal strength measured for the inter-RAT cell being greater than a configured threshold for a predetermined period of time on condition that it is determined that the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT.

6. The method as in claim 1, wherein the priority information is received via dedicated signaling.

7. The method as in claim 1, wherein the priority information is received via broadcast signaling.

8. The method as in claim 1, further comprising determining an order for measuring a plurality of cells associated with a plurality of RATs based on the priority information.

9. The method as in claim 1, further comprising:

reselecting to the inter-RAT cell based at least in part on there being no cells in a higher priority RAT that meet cell reselection requirements on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell associated with the current RAT.

10. The method as in claim 9, further comprising:

reselecting to the inter-RAT cell based at least in part on the Inter-RAT cell being higher ranked than the current cell on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell associated with the current RAT.

11. A wireless transmit receive unit (WTRU) comprising:

a receiver configured to receive priority information in a current cell associated with a current radio access technology (RAT), the priority information indicating a cell priority of an inter-RAT cell associated with a candidate RAT and relative to the current cell associated with the current RAT; and

a processor configured to;

determine whether the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT based on the priority information;

determine a cell selection value of the current cell;

determine to perform quality measurements of the inter-RAT cell associated with the candidate RAT on condition that it is determined that the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT; and

determine to perform quality measurements of the inter-RAT cell associated with the candidate RAT on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell in the current RAT and that the cell selection value of the current cell is less than or equal to a predetermined threshold.

12. The WTRU as in claim 11, wherein one of the current cell or the inter-RAT cell is a long term evolution (LTE) cell in an evolved universal terrestrial radio access network (E-UTRAN).

13. The WTRU as in claim 11, wherein the priority information includes frequency information for the inter-RAT cell.

14. The WTRU as in claim 11, wherein the processor is further configured to reselect to the inter-RAT cell based on the quality measurement.

15. The WTRU as in claim 11, wherein the processor is further configured to reselect to the inter-RAT cell based on a signal strength measured for the inter-RAT cell being greater than a configured threshold for a predetermined period of time on condition that it is determined that the inter-RAT cell associated with the candidate RAT has a higher priority than the current cell associated with the current RAT.

16. The WTRU as in claim 11, wherein the priority information is received via dedicated signaling.

17. The WTRU as in claim 11, wherein the priority information is received via broadcast signaling.

18. The WTRU as in claim 11, wherein the processor is further configured to determine an order for measuring a plurality of cells associated with a plurality of RATs based on the priority information.

19. The WTRU as in claim 11, wherein the processor is further configured to reselect to the inter-RAT cell based at least in part on there being no cells in a higher priority RAT that meet cell reselection requirements on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell associated with the current RAT.

20. The WTRU as in claim 19, wherein the processor is further configured to reselect to the inter-RAT cell based at least in part on the inter-RAT cell being higher ranked than the current cell on condition that it is determined that the inter-RAT cell associated with the candidate RAT does not have a higher priority than the current cell associated with the current RAT.