ALIGNING TIMING FOR DIRECT COMMUNICATIONS

• US 20140293968A1
• Filed: 04/01/2013
• Published: 10/02/2014
• Est. Priority Date: 04/01/2013
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Ebrahimi Tazeh Mahalleh, Masoud, Gage, William Anthony, Mukherjee, Biswaroop, Novak, Robert
• Granted Patent: US 9,232,488 B2
• Time in Patent Office: Days
• US Class Current: 370/336
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 56/004 compensating for timing error of reception due to propagation delay
• CPC Class Codes: H04W 76/23 Manipulation of direct-mode connections

Abstract

In some implementations, a method includes compensating for timing misalignment of subframes associated with at least one of first user equipment (UE) or a second UE. The first UE and the second UE are in an inter-device session (IDS) for direct UE-to-UE communication, and timing for the first UE and a timing for the second UE is derived from an eNode B (eNB).

Claims

1. A method, comprising:

compensating for timing misalignment of subframes associated with at least one of a first user equipment (UE) or a second UE, wherein the first UE and the second UE are in an inter-device session (IDS) for direct UE-to-UE communication, and a timing for the first UE and a timing for the second UE are derived from an eNode B (eNB).

2. The method of claim 1, wherein compensating for timing misalignment comprises compensating for a timing offset between the timing of the first UE and the timing of the second UE.

3. The method of claim 2, wherein compensating for a timing offset comprises adjusting a transmit time.

4. The method of claim 3, further comprising:

receiving, from the first UE, a timing reference signal (RS);

measuring, by the second UE, the timing offset between the first UE and the second UE; and

adjusting, by the second UE, the transmit time of the second UE using the timing offset.

5. The method of claim 4, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

6. The method of claim 3, further comprising:

transmitting, by the second UE, a timing RS;

receiving, from the first UE, the timing offset between the first UE and the second UE; and

adjusting, by the second UE, the transmit time of the second UE using the timing offset.

7. The method of claim 6, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

8. The method of claim 1, further comprising:

determining one or more contiguous physical resource block (PRB) groups allocated to the IDS; and

for each group of contiguous PRBs, allocating, as guard subcarriers, at least one of subcarriers with lowest indices in said each PRB group or subcarriers with highest indices in said each PRB group.

9. The method of claim 2, wherein compensating for timing offset comprises adjusting a receive window.

10. The method of claim 9, further comprising:

receiving, from the first UE, a timing RS;

measuring, by the second UE, the timing offset; and

adjusting, by the second UE, the receive window for the second UE using the timing offset.

11. The method of claim 10, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

12. The method of claim 1 wherein compensating for timing misalignment comprises transmitting subframes including guard periods, wherein each guard period is at least one of one or more contiguous symbols at a beginning of a subframe or one or more contiguous symbols at an end of a subframe.

13. The method of claim 12, wherein a guard period is one or more contiguous symbols at an end of a subframe, and the method further comprises:

determining a sounding reference signal (SRS) is being transmitted in the subframe; and

transmitting the SRS in the last symbol of the subframe, wherein transmitting the SRS overrides the last symbol of the guard period.

14. The method of claim 13, further comprising adding a guard period at a beginning of a subframe following the subframe including the SRS.

15. The method of claim 1, further comprising:

receiving, from the eNB, by the first UE, information identifying a size of a physical downlink control channel (PDCCH) for a subsequent subframe; and

adding, by the first UE, a guard period in a beginning of a subframe used for direct UE-to-UE communication to the second UE, the guard period being equal to or greater than the size of the PDDCH for the subsequent subframe.

16. A first UE, comprising:

one or more processors configured to;

compensate for timing misalignment of subframes associated with at least one of the first UE or a second UE, wherein the first UE and the second UE are in an IDS for direct UE-to-UE communication, and a timing for the first UE and a timing for the second UE are derived from an eNB.

17. The UE of claim 16, wherein compensating for timing misalignment comprises compensating for a timing offset between the timing of the first UE and the timing of the second UE.

18. The UE of claim 17, wherein compensating for a timing offset comprises adjusting a transmit time.

19. The UE of claim 18, the processors further operable to:

receive, from the first UE, a timing reference signal (RS);

measure, by the second UE, the timing offset between the first UE and the second UE; and

adjust, by the second UE, the transmit time of the second UE using the timing offset.

20. The UE of claim 19, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

21. The UE of claim 18, the processors further operable to:

transmit, by the second UE, a timing RS;

receive, from the first UE, the timing offset between the first UE and the second UE; and

adjust, by the second UE, the transmit time of the second UE using the timing offset.

22. The UE of claim 21, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

23. The UE of claim 16, the processors further operable to:

determine one or more contiguous physical resource block (PRB) groups allocated to the IDS; and

for each group of contiguous PRBs, allocate, as guard subcarriers, at least one of subcarriers with lowest indices in said each PRB group or subcarriers with highest indices in said each PRB group.

24. The UE of claim 17, wherein compensating for timing offset comprises adjusting a receive window.

25. The UE of claim 24, the processors further operable to:

receive, from the first UE, a timing RS;

measure, by the second UE, the timing offset; and

adjust, by the second UE, the receive window for the second UE using the timing offset.

26. The UE of claim 25, wherein resources used for the timing RS are signaled, by the eNB, to the first UE and the second UE.

27. The UE of claim 16, wherein compensating for timing misalignment comprises transmitting subframes including guard periods, wherein each guard period is at least one of one or more contiguous symbols at a beginning of a subframe or one or more contiguous symbols at an end of a subframe.

28. The UE of claim 27, wherein a guard period is one or more contiguous symbols at an end of a subframe, and the processors further operable to:

determine a sounding reference signal (SRS) is being transmitted in the subframe; and

transmit the SRS in the last symbol of the subframe, wherein transmitting the SRS overrides the last symbol of the guard period.

29. The UE of claim 28, the processors further operable to add a guard period at a beginning of a subframe following the subframe including the SRS.

30. The UE of claim 16, the processors further operable to:

receive, from the eNB, by the first UE, information identifying a size of a physical downlink control channel (PDCCH) for a subsequent subframe; and

add, by the first UE, a guard period in a beginning of a subframe used for direct UE-to-UE communication to the second UE, the guard period being equal to or greater than the size of the PDDCH for the subsequent subframe.