Device to-device synchronization
A wireless transmit receive unit (WTRU) may be operated in a first scheduling mode for device-to-device communication. In the first scheduling mode, a network entity may schedule resources to be used by the WTRU for device-to-device communications. The WTRU may detect that a radio link failure (RLF) timer is running or has been started. The WTRU may switch from the first scheduling mode for Data device-to-device communication to a second scheduling mode for device-to-device communication in response to detecting that the radio link failure timer is running or has been started. In the second scheduling mode, the WTRU may select a resource from a resource pool for the WTRU to use for one or more device-to-device communications.
1. A method comprising:
operating a wireless transmit receive unit (WTRU) in a first scheduling mode for device-to-device communication, wherein in the first scheduling mode a network entity schedules resources to be used by the WTRU for device-to-device communications;
detecting that a radio resource control (RRC) timer is running or has been started, wherein the RRC timer indicates a failure condition; and
switching the WTRU from the first scheduling mode for device-to-device communication to a second scheduling mode for device-to-device communication in response to detecting that the RRC timer is running or has been started, wherein in the second scheduling mode the WTRU autonomously selects a resource from a resource pool for the WTRU to use for one or more device-to-device communications.
2. The method of claim 1 , wherein the RRC timer comprises a radio link failure (RLF) timer.
3. The method of claim 1 , wherein the RRC timer comprises a timer T 310 .
4. The method of claim 1 , wherein the RRC timer starts in response to a number of consecutive out-of-synch transmit time intervals (TTIs) exceeding a threshold.
5. The method of claim 1 , wherein the RRC timer comprises a timer T 311 .
6. The method of claim 1 , wherein the RRC timer starts in response to a RRC connection re-establishment procedure being initiated.
7. The method of claim 1 , wherein the RRC timer comprises a timer T 301 .
8. The method of claim 7 , further comprising ceasing operation of the WTRU in the second scheduling mode upon detecting that the timer T 301 is not running.
9. The method of claim 1 , wherein the RRC timer starts in response to a request to reestablish radio resource control (RRC) connection being transmitted.
10. The method of claim 9 , further comprising ceasing operation of the WTRU in the second scheduling mode upon reestablishment of the RRC connection.
11. The method of claim 1 , wherein operating the WTRU in the second scheduling mode comprises operating the WTRU using fixed power control.
12. A wireless transmit/receive unit (WTRU) comprising:
a processor configured to:
operate the WTRU in a first scheduling mode for device-to-device communication, wherein in the first scheduling mode a network entity schedules resources to be used by the WTRU for device-to-device communications;
detect that a radio resource configuration (RRC) timer is running or has been started, wherein the RRC timer indicates a failure condition; and
switch the WTRU from the first scheduling mode for device-to-device communication to a second scheduling mode for device-to-device communication in response to detecting that the RRC timer is running or has been started, wherein in the second scheduling mode the WTRU autonomously selects a resource from a resource pool for the WTRU to use for one or more device-to-device communications.
13. The WTRU of claim 12 , wherein the RRC timer comprises a radio link failure (RLF) timer.
14. The WTRU of claim 12 , wherein the RRC timer comprises a timer T 310 .
15. The WTRU of claim 12 , wherein the RRC timer starts in response to a number of consecutive out-of-synch transmit time intervals (TTIs) exceeding a threshold.
16. The WTRU of claim 12 , wherein the RRC timer comprises a timer T 311 .
17. The WTRU of claim 12 , wherein the RRC timer starts in response to a RRC connection re-establishment procedure being initiated.
18. The WTRU of claim 12 , wherein the RRC timer comprises a timer T 301 .
19. The WTRU of claim 18 , wherein the processor is further configured to:
detect that the timer 301 has expired; and
cease operation of the WTRU in the second scheduling mode upon expiration of the timer T 301 .
20. The WTRU of claim 12 , wherein the RRC timer starts in response to a request to reestablish radio resource control (RRC) connection being transmitted.
21. The WTRU of claim 20 , wherein the processor is further configured to:
detect reestablishment of the RRC connection; and
cease operation of the WTRU in the second scheduling mode upon reestablishment of the RRC connection.
22. The WTRU of claim 12 , wherein the processor is configured to operate the WTRU using fixed power control in the second scheduling mode.