Flexible comb-based reference signals

• US 10,498,506 B2
• Filed: 01/18/2018
• Issued: 12/03/2019
• Est. Priority Date: 01/26/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wang, Renqiu, Huang, Yi, Xu, Hao, Zeng, Wei, Gaal, Peter
• Primary Examiner(s): Zhao, Wei
• Application Number:
  US15/874,712
• Publication Number:
  US 20180212728A1
• Time in Patent Office: 684 Days
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• 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: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

Multiple-input, multiple-output (MIMO) devices and non-MIMO devices may implement a flexible comb-based design for transmission of reference signals, such as demodulation reference signals (DMRSs). User equipment (UEs) of different ranks may use the flexible comb-based design to transmit the reference signals in a common comb pattern within an allocated bandwidth. UEs using as many antenna ports as combs in the common comb pattern may transmit a different reference signal using a different antenna port over each comb, while UEs using fewer antenna ports than combs may concatenate combs, so that the UEs may transmit a reference signal using a single antenna port over multiple combs. Using the flexible comb-based design, a base station may be capable of better manage inter-cell interference and multiplexing of different rank UEs in shared resource blocks (RBs) may be supported.

Claims

1. A method for wireless communication, comprising:

identifying a number of antenna ports to use for transmission of one or more reference signals in a symbol having a multiple-comb pattern, each comb of the multiple-comb pattern comprising a set of subcarriers within a set of resources allocated for reference signal transmission;

determining, for each antenna port, a number of combs to use for transmission of at least one of the one or more reference signals based at least in part on the number of antenna ports; and

transmitting, using each antenna port, at least one of the one or more reference signals based at least in part on the determined number of combs.

2. The method of claim 1, further comprising:

receiving, from a base station, a scheduling grant comprising an antenna index and a comb index; and

transmitting at least one of the one or more reference signals based at least in part on the antenna index and the comb index.

3. The method of claim 1, further comprising:

determining an antenna index and a comb index for a user equipment (UE); and

transmitting, to the UE, a scheduling grant comprising the antenna index and the comb index.

4. The method of claim 1, wherein transmitting the at least one of the one or more reference signals comprises:

determining that the number of antenna ports is equal to a total number of combs in the multiple-comb pattern;

allocating each comb of the multiple-comb pattern to a respective antenna port; and

transmitting the at least one of the one or more reference signals based at least in part on the allocating.

5. The method of claim 1, wherein transmitting the at least one of the one or more reference signals comprises:

determining that the number of antenna ports is equal to one half of a total number of combs in the multiple-comb pattern;

allocating every other comb of the multiple-comb pattern to a respective antenna port; and

transmitting the at least one of the one or more reference signals based at least in part on the allocating.

6. The method of claim 1, wherein transmitting the at least one of the one or more reference signals comprises:

determining that the number of antenna ports is equal to one;

allocating every comb of the multiple-comb pattern to a single antenna port; and

transmitting the at least one of the one or more reference signals based at least in part on the allocating.

7. The method of claim 1, wherein transmitting the at least one of the one or more reference signals comprises:

transmitting, at a first antenna port, a first reference signal using a first comb of the multiple-comb pattern; and

transmitting, at a second antenna port, a second reference signal using a second comb of the multiple-comb pattern.

8. The method of claim 7, wherein:

the first reference signal comprises a first sub-sequence of a base sequence and the second reference signal comprises a second sub-sequence of the base sequence.

9. The method of claim 8, wherein:

the base sequence consists of the first sub-sequence and the second sub-sequence.

10. The method of claim 1, wherein transmitting the at least one of the one or more reference signals comprises:

transmitting a first reference signal using a subset of combs of the multiple-comb pattern.

11. The method of claim 1, wherein:

a first set of subcarriers for a first comb of the multiple-comb pattern is non-overlapping with a second set of subcarriers for a second comb of the multiple-comb pattern.

12. The method of claim 1, wherein:

the multiple-comb pattern comprises multiple combs that are frequency multiplexed across one or more symbol periods.

13. The method of claim 1, further comprising:

allocating the set of resources to multiple UEs including a first UE and a second UE different from the first UE.

14. The method of claim 13, wherein:

a determined number of combs for each antenna port of the first UE is equal to or different from a determined number of combs for each antenna port of the second UE.

15. An apparatus for wireless communication, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

identify a number of antenna ports to use for transmission of one or more reference signals in a symbol having a multiple-comb pattern, each comb of the multiple-comb pattern comprising a set of subcarriers within a set of resources allocated for reference signal transmission;

determine, for each antenna port, a number of combs to use for transmission of at least one of the one or more reference signals based at least in part on the number of antenna ports; and

transmit, using each antenna port, at least one of the one or more reference signals based at least in part on the determined number of combs.

16. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

receive, from a base station, a scheduling grant comprising an antenna index and a comb index; and

transmit at least one of the one or more reference signals based at least in part on the antenna index and the comb index.

17. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

determine an antenna index and a comb index for a user equipment (UE); and

transmit, to the UE, a scheduling grant comprising the antenna index and the comb index.

18. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

determine that the number of antenna ports is equal to a total number of combs in the multiple-comb pattern;

allocate each comb of the multiple-comb pattern to a respective antenna port; and

transmit the at least one of the one or more reference signals based at least in part on the allocating.

19. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

determining that the number of antenna ports is equal to one half of a total number of combs in the multiple-comb pattern;

allocate every other comb of the multiple-comb pattern to a respective antenna port; and

transmit the at least one of the one or more reference signals based at least in part on the allocating.

20. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

determine that the number of antenna ports is equal to one;

allocate every comb of the multiple-comb pattern to a single antenna port; and

transmit the at least one of the one or more reference signals based at least in part on the allocating.

21. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

transmit, at a first antenna port, a first reference signal using a first comb of the multiple-comb pattern; and

transmit, at a second antenna port, a second reference signal using a second comb of the multiple-comb pattern.

22. The apparatus of claim 21, wherein:

the first reference signal comprises a first sub-sequence of a base sequence and the second reference signal comprises a second sub-sequence of the base sequence.

23. The apparatus of claim 22, wherein:

the base sequence consists of the first sub-sequence and the second sub-sequence.

24. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

transmit a first reference signal using a subset of combs of the multiple-comb pattern.

25. The apparatus of claim 15, wherein:

a first set of subcarriers for a first comb of the multiple-comb pattern is non-overlapping with a second set of subcarriers for a second comb of the multiple-comb pattern.

26. The apparatus of claim 15, wherein:

the multiple-comb pattern comprises multiple combs that are frequency multiplexed across one or more symbol periods.

27. The apparatus of claim 15, wherein the instructions are further executable by the processor to:

allocate the set of resources to multiple UEs including a first UE and a second UE different from the first UE.

28. The apparatus of claim 27, wherein:

a determined number of combs for each antenna port of the first UE is equal to or different from a determined number of combs for each antenna port of the second UE.

29. An apparatus for wireless communication, comprising:

means for identifying a number of antenna ports to use for transmission of one or more reference signals in a symbol having a multiple-comb pattern, each comb of the multiple-comb pattern comprising a set of subcarriers within a set of resources allocated for reference signal transmission;

means for determining, for each antenna port, a number of combs to use for transmission of at least one of the one or more reference signals based at least in part on the number of antenna ports; and

means for transmitting, using each antenna port, at least one of the one or more reference signals based at least in part on the determined number of combs.

30. A non-transitory computer readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:

identify a number of antenna ports to use for transmission of one or more reference signals in a symbol having a multiple-comb pattern, each comb of the multiple-comb pattern comprising a set of subcarriers within a set of resources allocated for reference signal transmission;

determine, for each antenna port, a number of combs to use for transmission of at least one of the one or more reference signals based at least in part on the number of antenna ports; and

transmit, using each antenna port, at least one of the one or more reference signals based at least in part on the determined number of combs.