Adaptive maintenance of uplink time alignment

• US 9,094,904 B2
• Filed: 03/11/2013
• Issued: 07/28/2015
• Est. Priority Date: 10/25/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ramkumar, Vasanth Kumar, Rajagopalan, Srinivasan, Nguyen, Bao Vinh, Krishnamoorthi, Deepak
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US13/793,062
• Publication Number:
  US 20140119247A1
• Time in Patent Office: 869 Days
• Field of Search: 370/329, 370/350, 370/510
• US Class Current: 1/1
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time

Abstract

A method for wireless communication is disclosed. A time alignment timer is started. It is determined when the time alignment timer will expire. A time alignment request subframe that is prior to the time alignment timer expiring is identified. Uplink time alignment is requested in the time alignment request subframe.

Claims

1. An apparatus configured for wireless communication, comprising:

means for starting a time alignment timer;

means for determining when the time alignment timer will expire;

means for identifying a time alignment request subframe that is prior to the time alignment timer expiring on a condition that a timing alignment command cannot be received before the time alignment timer expires, which is determined based on a multimedia broadcast over a single frequency network subframe configuration or a measurement gap configuration; and

means for requesting uplink time alignment in the time alignment request subframe.

2. The apparatus of claim 1, wherein the time alignment request subframe is a last uplink subframe preceding the expiration of the time alignment timer.

3. The apparatus of claim 1, wherein the apparatus operates in a multicast broadcast over a single frequency network.

4. The apparatus of claim 1, further comprising means for receiving the timing alignment command.

5. The apparatus of claim 4, wherein the timing alignment command is received in a random access response protocol data unit.

6. The apparatus of claim 1, wherein the timing alignment command is received in a first downlink subframe following the expiration of the time alignment timer.

7. The apparatus of claim 1, wherein the uplink time alignment is requested using a random access channel procedure.

8. The apparatus of claim 1, wherein the apparatus is operating in a time division duplex system.

9. The apparatus of claim 1, wherein the apparatus is operating in a frequency division duplex system.

10. An apparatus, comprising:

circuitry configured to start a time alignment timer, to determine when the time alignment timer will expire, to identify a time alignment request subframe that is prior to the time alignment timer expiring on a condition that a timing alignment command cannot be received before the time alignment timer expires, which is determined based on a multimedia broadcast over a single frequency network subframe configuration or a measurement gap configuration, and to request uplink time alignment in the time alignment request subframe.

11. The apparatus of claim 10, wherein the time alignment request subframe is a last uplink subframe preceding the expiration of the time alignment timer.

12. The apparatus of claim 10, wherein the apparatus operates in a multicast broadcast over a single frequency network.

13. The apparatus of claim 10, further comprising circuitry configured to receive the timing alignment command.

14. The apparatus of claim 13, wherein the timing alignment command is received in a random access response protocol data unit.

15. The apparatus of claim 10, wherein the timing alignment command is received in a first downlink subframe following the expiration of the time alignment timer.

16. The apparatus of claim 10, wherein the uplink time alignment is requested using a random access channel procedure.

17. The apparatus of claim 10, wherein the apparatus is operating in a time division duplex system.

18. The apparatus of claim 10, wherein the apparatus is operating in a frequency division duplex system.

19. A method for wireless communication, comprising:

starting a time alignment timer;

determining when the time alignment timer will expire;

identifying a time alignment request subframe that is prior to the time alignment timer expiring on a condition that a timing alignment command cannot be received before the time alignment timer expires, which is determined based on a multimedia broadcast over a single frequency network subframe configuration or a measurement gap configuration; and

requesting uplink time alignment in the time alignment request subframe.

20. The method of claim 19, wherein the time alignment request subframe is a last uplink subframe preceding the expiration of the time alignment timer.

21. The method of claim 19, wherein the method is performed in a multicast broadcast over a single frequency network.

22. The method of claim 19, further comprising receiving a timing alignment command.

23. The method of claim 22, wherein the timing alignment command is received in a random access response protocol data unit.

24. The method of claim 19, wherein the timing alignment command is received in a first downlink subframe following the expiration of the time alignment timer.

25. The method of claim 19, wherein the uplink time alignment is requested using a random access channel procedure.

26. The method of claim 19, wherein the method is performed in a time division duplex system.

27. The method of claim 19, wherein the method is performed in a frequency division duplex system.

28. A non-transitory computer-readable medium having instructions thereon, the instructions comprising:

code for causing a wireless device to start a time alignment timer;

code for causing the wireless device to determine when the time alignment timer will expire;

code for causing the wireless device to identify a time alignment request subframe that is prior to the time alignment timer expiring on a condition that a timing alignment command cannot be received before the time alignment timer expires, which is determined based on a multimedia broadcast over a single frequency network subframe configuration or a measurement gap configuration; and

code for causing the wireless device to request uplink time alignment in the time alignment request subframe.

29. The non-transitory computer-readable medium of claim 28, wherein the time alignment request subframe is a last uplink subframe preceding the expiration of the time alignment timer.

30. The non-transitory computer-readable medium of claim 28, wherein the wireless device operates in a multicast broadcast over a single frequency network.

31. The non-transitory computer-readable medium of claim 28, further comprising code for causing the wireless device to receive a timing alignment command.