Device to-device synchronization

• US 10,129,902 B2
• Filed: 03/19/2015
• Issued: 11/13/2018
• Est. Priority Date: 03/19/2014
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Kaur, Samian, Pani, Diana, Zhao, Yuxin, Pelletier, Benoit
• Primary Examiner(s): Huq, Obaidul
• Application Number:
  US15/127,385
• Publication Number:
  US 20170142741A1
• Time in Patent Office: 1,335 Days
• Field of Search: 370310, 370328, 370329, 370336
• CPC Class Codes: H04W 52/383 power control in peer-to-peer links
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/121 for groups of terminals or users
• CPC Class Codes: H04W 76/14 Direct-mode setup
• 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 76/23 Manipulation of direct-mode connections

Abstract

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.

Claims

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 T310.

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 T311.

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 T301.

8. The method of claim 7, further comprising ceasing operation of the WTRU in the second scheduling mode upon detecting that the timer T301 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 T310.

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 T311.

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 T301.

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 T301.

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.