DOWNLINK OPERATIONS WITH SHORTENED TRANSMISSION TIME INTERVALS

• US 20170238312A1
• Filed: 12/02/2016
• Published: 08/17/2017
• Est. Priority Date: 02/16/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: GAAL, Peter, CHEN, Wanshi, MONTOJO, Juan, PATEL, Shimman, DAMNJANOVIC, Aleksandar, XU, Hao
• Granted Patent: US 10,085,256 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 5/0014 Three-dimensional division time-code-space division H04B7/0413, H04B7/0697
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management

Abstract

Aspects of the present disclosure generally relate to a conditional utilization of reference signals for managing communications of one or more user equipment (UE) in a wireless communications system. The described aspects include receiving a transmission having a first subframe slot and a second subframe slot, at least one of the first subframe slot and the second subframe slot have a single-slot transmission time interval (TTI). The described aspects further include detecting a first demodulation reference signal (DM-RS) in the first subframe slot and a second DM-RS in the second subframe slot. The described aspects further include determining whether to demodulate the at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or to demodulate both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot based on whether at least one condition exists.

Claims

1. A method for wireless communications, comprising:

receiving a transmission having a first subframe slot and a second subframe slot, wherein at least one of the first subframe slot and the second subframe slot have a single-slot transmission time interval (TTI);

detecting a first demodulation reference signal (DM-RS) in the first subframe slot and a second DM-RS in the second subframe slot;

determining, via a processor, whether at least one condition exists for using the second DM-RS in the second subframe slot for demodulating at least one downlink channel in the first subframe slot; and

determining whether to demodulate at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or using both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot based on whether the at least one condition exists.

2. The method of claim 1, wherein the condition comprises an indication to use the second DM-RS in the second subframe slot for demodulating the at least one downlink channel in the first subframe slot.

3. The method of claim 2, wherein the indication to use the second DM-RS further comprises at least one of:

a known radio resource control (RRC) configuration associated with using the second DM-RS;

or

a known downlink control information (DCI) format associated with using the second DM-RS.

4. The method of claim 2, wherein the indication to use the second DM-RS further comprises an identifier of other resource elements in a same slot to be used for demodulation.

5. The method of claim 2, wherein the indication to use the second DM-RS further comprises an implicit indication associated with using the second DM-RS.

6. The method of claim 5, wherein the implicit indication comprises at least one of:

a known rank transmission scheduled in the first subframe slot;

or

a control signal transmitted in the second subframe slot for a scheduled data transmission in the first subframe slot.

7. The method of claim 1, wherein detecting the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot further comprises:

detecting the first DM-RS in at least one resource block of the first subframe slot;

detecting the second DM-RS in at least one resource block of the second subframe slot; and

wherein the determining whether the condition exists further comprises determining for each of the at least one resource block of the first subframe slot and for each of the at least one resource block of the second subframe slot.

8. The method of claim 1, wherein first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot are associated with a same group of antenna ports.

9. The method of claim 1, wherein the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot are associated with an orthogonal cover code (OCC) of length 2 or of length 4.

10. The method of claim 1, further comprising performing channel rate matching around the first DM-RS and the second DM-RS in the second subframe slot when at least one channel scheduled in the second subframe slot is transmitted with a set of antenna ports in an antenna port group different from the antenna port group in the second subframe slot.

11. The method of claim 1, wherein the first DM-RS in the first subframe slot corresponds to a first group of antenna ports and the second DM-RS in the second subframe slot corresponds to a second group of antenna ports different from the first group of antenna ports.

12. The method of claim 1, wherein the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot are each associated with a different length of an orthogonal cover code (OCC).

13. The method of claim 1, further comprising:

determining a resource availability in the first subframe slot corresponding to a number of available resource elements for a data channel;

comparing the resource availability with a threshold;

scaling a transport block size for the first subframe slot based on the comparison.

14. The method of claim 13, wherein the threshold is at least one of a predetermined value or a value indicated by a network.

15. The method of claim 1, further comprising sharing a hybrid automatic repeat request (HARQ) process between the at least one downlink channel having the single-slot TTI and at least one other downlink channel included in a downlink subframe, wherein the at least one other downlink channel has a subframe length TTI.

16. The method of claim 1, further comprising:

maintaining at least one first hybrid automatic repeat request (HARQ) process for the at least one downlink channel having the single-slot TTI;

maintaining at least one second HARQ process for at least one other downlink channel included in a downlink subframe, wherein the at least one other downlink channel has a subframe length TTI; and

partitioning a soft buffer for storing symbols for the at least one first HARQ process and the at least one second HARQ process.

17. The method of claim 1, wherein a same precoding and power are used for both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot.

18. The method of claim 1, further comprising:

receiving a power difference indication that identifies a power difference between the first subframe slot and the second subframe slot; and

wherein the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot are demodulated, respectively, based on the power difference.

19. The method of claim 1, further comprising demodulating the at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot.

20. The method of claim 1, wherein the first subframe slot comprises a set of symbols including one or more symbols in a slot of a first subframe, and one or more symbols in a slot of a second subframe.

21. The method of claim 1, wherein the first subframe slot and the second subframe slot correspond to at least one of a same subframe or a different subframe.

22. The method of claim 1, wherein the second subframe slot precedes in time at least one of the first subframe slot or the second subframe slot.

23. An apparatus for wireless communication, comprising:

means for receiving a transmission having a first subframe slot and a second subframe slot, wherein at least one of the first subframe slot and the second subframe slot have a single-slot transmission time interval (TTI);

means for detecting a first demodulation reference signal (DM-RS) in the first subframe slot and a second DM-RS in the second subframe slot;

means for determining, via a processor, whether at least one condition exists for using the second DM-RS in the second subframe slot for demodulating at least one downlink channel in the first subframe slot; and

means for determining whether to demodulate the at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or using both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot based on whether the at least one condition exists.

24. The apparatus of claim 23, wherein the condition comprises an indication to use the second DM-RS in the second subframe slot for demodulating the at least one downlink channel in the first subframe slot.

25. An apparatus for wireless communication, comprising:

a transceiver;

a memory; and

at least one processor coupled to the memory and configured to;

receive, via the transceiver, a transmission having a first subframe slot and a second subframe slot, wherein at least one of the first subframe slot and the second subframe slot have a single-slot transmission time interval (TTI);

detect a first demodulation reference signal (DM-RS) in the first subframe slot and a second DM-RS in the second subframe slot;

determine whether at least one condition exists for using the second DM-RS in the second subframe slot for demodulating at least one downlink channel in the first subframe slot; and

determine whether to demodulate the at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or using both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot based on whether the at least one condition exists.

26. The apparatus of claim 25, wherein the condition comprises an indication to use the second DM-RS in the second subframe slot for demodulating the at least one downlink channel in the first subframe slot.

27. The apparatus of claim 26, wherein the indication to use the second DM-RS further comprises at least one of:

a known radio resource control (RRC) configuration associated with using the second DM-RS;

or

a known downlink control information (DCI) format associated with using the second DM-RS.

28. The apparatus of claim 25, wherein the at least one processor configured to detect the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot is further configured to:

detect the first DM-RS in at least one resource block of the first subframe slot; and

detect the second DM-RS in at least one resource block of the second subframe slot; and

wherein the at least one processor configured to determine whether the condition exists is further configured to determine for each of the at least one resource block of the first subframe slot and for each of the at least one resource block of the second subframe slot.

29. A computer-readable medium storing computer executable code, comprising code to:

receiving a transmission having a first subframe slot and a second subframe slot, wherein at least one of the first subframe slot and the second subframe slot have a single-slot transmission time interval (TTI);

detecting a first demodulation reference signal (DM-RS) in the first subframe slot and a second DM-RS in the second subframe slot;

determining, via a processor, whether at least one condition exists for using the second DM-RS in the second subframe slot for demodulating at least one downlink channel in the first subframe slot; and

determining whether to demodulate the at least one downlink channel in the first subframe slot using the first DM-RS in the first subframe slot or using both the first DM-RS in the first subframe slot and the second DM-RS in the second subframe slot based on whether the at least one condition exists.

30. The computer-readable medium of claim 29, wherein the condition comprises an indication to use the second DM-RS in the second subframe slot for demodulating the at least one downlink channel in the first subframe slot.