METHOD AND APPARATUS FOR MONITORING FOR A RADIO LINK FAILURE

• US 20110021154A1
• Filed: 03/12/2010
• Published: 01/27/2011
• Est. Priority Date: 03/12/2009
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Pelletier, Ghyslain, Marinier, Paul, Terry, Stephen E., Wang, Peter S., Gauvreau, Jean-Louis, Rudolf, Marian, Somasundaram, Shankar
• Granted Patent: US 8,711,709 B2
• Time in Patent Office: Days
• US Class Current: 455/67.11
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 76/18 Management of setup rejection or failure
• CPC Class Codes: H04W 76/19 Connection re-establishment
• CPC Class Codes: H04W 76/38 triggered by timers

Abstract

Methods and apparatus are described for monitoring for a radio link failure in a long term evolution-advanced (LTE-A) system operated with carrier aggregation. The methods include criteria for determining radio link failure, recovery events, and the actions that a wireless transmit/receive unit (WTRU) may take upon the occurrence of such events.

Claims

1. A method, implemented by a wireless transmit/receive unit (WTRU), of monitoring for a radio link failure, the method comprising:

determining a primary downlink (DL) carrier among a set of component carriers configured or activated for the WTRU;

counting out-of-synch indications from the primary DL carrier using a first counter in the WTRU;

initiating a recovery timer in the WTRU on a condition that a predefined number of out-of-synch indications from the primary DL carrier was counted, as determined by the first counter; and

counting in-synch indications from the primary DL carrier using a second counter in the WTRU.

2. The method of claim 1 further comprising:

declaring a radio link failure on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires; and

initiating a radio resource control (RRC) connection re-establishment procedure, wherein the WTRU selects a cell corresponding to one of the component carriers for which a radio problem does not exist.

3. The method of claim 1 further comprising:

declaring a radio link failure on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires; and

transmitting a radio resource control (RRC) connection re-establishment message by initiating a random access channel (RACH) procedure using resources broadcast by a cell selected by the WTRU that corresponds to one of the component carriers for which a radio problem does not exist.

4. The method of claim 1 further comprising:

declaring a radio link failure on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires;

transmitting a scheduling request (SR) on a physical uplink control channel (PUCCH); and

transmitting a radio resource control (RRC) connection re-establishment message.

5. The method of claim 4 wherein the PUCCH is allocated on an uplink (UL) carrier paired to a DL carrier that does not have a radio problem.

6. The method of claim 1 wherein the primary DL carrier is selected from a plurality of DL carriers, wherein the selected primary DL carrier has the highest coverage among the plurality of DL carriers.

7. The method of claim 1 wherein the primary DL carrier is selected from a plurality of DL carriers, wherein the selected primary DL carrier provides physical downlink control channel (PDCCH) signaling.

8. The method of claim 1 wherein the primary DL carrier is selected from a plurality of DL carriers that are in discontinuous reception (DRX) active time based on a predefined or signaled priority.

9. The method of claim 1 wherein the primary DL carrier is obtained from a network through radio resource control (RRC) signaling.

10. The method of claim 1 further comprising:

declaring a radio link failure on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires; and

performing either a connection re-establishment procedure or a radio resource control (RRC) connection release procedure on a condition that a radio link failure is declared.

11. The method of claim 1 further comprising:

on a condition that a predefined number of in-synch indications was received from the primary carrier before the recovery timer expires, stopping the recovery timer.

12. The method of claim 1 further comprising:

on a condition that a predefined number of in-synch indications was not received from the primary carrier before the recovery timer expires, performing a primary re-establishment procedure.

13. A method, implemented by a wireless transmit/receive unit (WTRU), of monitoring for a radio link failure, the method comprising:

counting out-of-synch indications from each of a plurality of physical downlink control channel (PDCCH) carriers activated for the WTRU;

initiating a recovery timer in the WTRU on a condition that a predefined number of out-of-synch indications from a particular one of the PDCCH carriers was counted; and

counting in-synch indications from the particular PDCCH carrier.

14. The method of claim 13 further comprising:

declaring a partial radio link failure associated with the particular PDCCH on a condition that the recovery timer expires before a predefined number of in-synch indications is counted.

15. A wireless transmit/receive unit (WTRU) for monitoring for a radio link failure, the WTRU comprising:

a processor configured to determine a primary downlink (DL) carrier among a set of component carriers configured or activated for the WTRU;

a first counter configured to count out-of-synch indications from the primary DL carrier;

a recovery timer configured to be initiated on a condition that a predefined number of out-of-synch indications from the primary DL carrier was counted, as determined by the first counter; and

a second counter configured to count in-synch indications from the primary DL carrier.

16. The WTRU of claim 15 wherein a radio link failure is declared on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires, and a radio resource control (RRC) connection re-establishment procedure is initiated, wherein the WTRU selects a cell corresponding to one of the component carriers for which a radio problem does not exist.

17. The WTRU of claim 15 wherein a radio link failure is declared on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires, and a radio resource control (RRC) connection re-establishment message is transmitted by initiating a random access channel (RACH) procedure using resources broadcast by a cell selected by the WTRU that corresponds to one of the component carriers for which a radio problem does not exist.

18. The WTRU of claim 15 wherein a radio link failure is declared on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires, a scheduling request (SR) is transmitted on a physical uplink control channel (PUCCH), and a radio resource control (RRC) connection re-establishment message is transmitted.

19. The WTRU of claim 18 wherein the PUCCH is allocated on an uplink (UL) carrier paired to a DL carrier that does not have a radio problem.

20. The WTRU of claim 15 wherein the primary DL carrier is selected from a plurality of DL carriers, wherein the selected primary DL carrier has the highest coverage among the plurality of DL carriers.

21. The WTRU of claim 15 wherein the primary DL carrier is selected from a plurality of DL carriers, wherein the selected primary DL carrier provides physical downlink control channel (PDCCH) signaling.

22. The WTRU of claim 15 wherein the primary DL carrier is selected from a plurality of DL carriers that are in discontinuous reception (DRX) active time based on a predefined or signaled priority.

23. The WTRU of claim 15 wherein the primary DL carrier is obtained from a network through radio resource control (RRC) signaling.

24. The WTRU of claim 15 wherein a radio link failure is declared on a condition that a predefined number of in-synch indications from the primary DL carrier is not counted by the second counter before the recovery timer expires, and either a connection re-establishment procedure or a radio resource control (RRC) connection release procedure is performed on a condition that a radio link failure is declared.

25. The WTRU of claim 15 wherein the recovery timer is stopped on a condition that a predefined number of in-synch indications was received from the primary carrier before the recovery timer expires.

26. The WTRU of claim 15 wherein a primary re-establishment procedure is performed on a condition that a predefined number of in-synch indications was not received from the primary carrier before the recovery timer expires.

27. A wireless transmit/receive unit (WTRU) for monitoring for a radio link failure, the WTRU comprising:

a plurality of out-of-synch indication counters configured to count out-of-synch indications from each of a plurality of physical downlink control channel (PDCCH) carriers activated for the WTRU;

a recovery timer configured to be initiated on a condition that a predefined number of out-of-synch indications from a particular one of the PDCCH carriers was counted; and

an in-synch indication counter configured to count in-synch indications from the particular PDCCH carrier.

28. The WTRU of claim 27 wherein a partial radio link failure associated with the particular PDCCH is declared on a condition that the recovery timer expires before a predefined number of in-synch indications is counted.