CELL RESELECTION PROCESS FOR WIRELESS COMMUNICATIONS

• US 20080227453A1
• Filed: 03/13/2008
• Published: 09/18/2008
• Est. Priority Date: 03/13/2007
• Status: Abandoned Application

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Sammour, Mohammed, Somasundaram, Shankar, Olvera-Hernandez, Ulises
• Application Number:
  US12/047,786
• Publication Number:
  US 20080227453A1
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

A method of cell reselection in a wireless communications system where parameters are transmitted by the network in system information blocks to WTRU'"'"'s on the network. Parameters are either added or subtracted from an equation representing the signal power and/or quality of a cell. Parameters may be prioritized. The results of the calculations are used to rank the servicing cell and neighboring cells. If a neighboring cell has a higher quality than the servicing cell, then the WTRU reselects the better cell. The network may transmit a blacklist of cells where the WTRU cannot camp as well as a barring timer for each cell where if the timer expires, the cell may again be considered for reselection. Information germane to the reselection decision may be transmitted and used by the network.

Claims

1. A method, implemented by a wireless transmit/receive unit (WTRU), for determining whether to switch from a servicing wireless communication cell to a neighboring cell comprising:

receiving at least one parameter relating to a cell reselection decision;

calculating a cell ranking measurement, wherein the at least one parameter is added to make it more likely the WTRU will camp on a cell associated with the parameter, or the at least one parameter is subtracted to make it less likely the WTRU will camp on a cell associated with the parameter;

ranking the servicing cell and the at least one neighboring cell based on the cell ranking measurement;

making a cell reselection decision based on the cell rankings.

2. The method of claim 1 wherein the at least one parameter is transmitted in a system information block (SIB).

3. The method of claim 1, wherein at least one parameter is selected from the group of consisting of cell load, bandwidth capabilities, and subscribed services.

4. The method of claim 1 wherein the cell ranking measurement is based, at least in part, on cell signal quality.

5. The method of claim 1 wherein the cell measurement is based, at least in part, on cell signal power.

6. A method of reselecting a wireless communication cell comprising:

determining if a cell should allow a WTRU to camp on the cell;

adding the cell to a blacklist if it is determined a WTRU should not camp on the cell;

transmitting the blacklist to a WTRU;

referencing the blacklist when ranking cells for reselection;

excluding cells contained on the blacklist when performing cell reselection;

creating a cell ranking based on non-excluded cells.

7. A method of ranking wireless communication cells for cell reselection comprising:

identifying a plurality of parameters for a cell reselection decision;

assigning a priority to each parameter;

calculating a cell ranking measurement based upon the parameters and associated priorities, wherein a parameter is added to make it more likely the WTRU will camp on a cell associated with the parameter or is subtracted to make it less likely the WTRU will camp on a cell associated with the parameter;

making a cell reselection decision based on the cell rankings.

8. A method of wireless communication cell reselection comprising;

receiving a plurality of parameters representing factors in the cell reselection process;

calculating a cell measurement based upon the plurality of parameters;

determining a cell ranking based upon the calculations; and

making a reselection decision based on the cell ranking.

9. The method of claim 8, wherein each of the plurality of parameters is assigned a priority.

10. The method of claim 8, wherein the cell measurement is a cell signal power measurement.

11. The method of claim 8, wherein the cell measurement is a cell signal quality measurement.

12. A wireless transmit/receive unit (WTRU) comprising:

a receiver configured to receive at least one parameter relevant to a cell reselection decision;

a cell ranking unit configured to calculate a cell ranking measurement based upon at least one parameter, wherein a parameter is added to make it more likely the WTRU will camp on a cell associated with the parameter or subtracted to make it less likely the WTRU will camp on a cell associated with the parameter and ranking a servicing cell and at least one neighboring cell based on the cell ranking measurement;

a cell reselection unit configured to make a cell reselection decision based on cell rankings.

13. The WTRU of claim 12, wherein one of the parameters is selected from the group consisting of cell load, bandwidth capabilities, and subscribed services.

14. The WTRU of claim 12 wherein the calculation is based on cell signal quality.

15. The WTRU of claim 12 wherein the calculation is based on cell signal power level.

16. A wireless receive/transmit unit (WTRU) comprising:

a receiver configured to receive at least one parameter related to a cell reselection decision;

a cell ranking unit configured to calculate a measurement associated with a cell, wherein the at least one parameter is added to make it more likely that the WTRU will select a cell under consideration for reselection or the at least one parameter is subtracted to make it less likely that the WTRU will select a cell under consideration for reselection.

17. The WTRU of claim 16, wherein one of the parameters is selected from the group of cell load, bandwidth capabilities, and subscribed services.

18. The WTRU of claim 16 wherein the equation calculates a cell measurement based on cell signal quality.

19. The WTRU of claim 16 wherein the equation calculates a cell measurement based on cell signal power level.

20. The WTRU of claim 16 wherein a parameter Q_cell—

_access is created using information based on cell load and bandwidth capabilities of a cell.

21. The WTRU of claim 16 wherein the receiver is further configure to receive in a system information message an inability of a cell to support services to which a WTRU is subscribed and excluding the unable cell from cell reselection and selecting a next highest ranked cell for reselection.