Method and apparatus for transmitting and receiving demodulation reference signal

• US 10,644,849 B2
• Filed: 03/23/2018
• Issued: 05/05/2020
• Est. Priority Date: 03/23/2017
• Status: Active Grant

• Current Assignee: Innovative Tech Lab Company Limited
• Original Assignee: Innovative Tech Lab Company Limited
• Inventors: Yoon, Sung Jun
• Primary Examiner(s): Nawaz, Asad M
• Assistant Examiner(s): Harley, Jason A
• Application Number:
  US15/933,823
• Publication Number:
  US 20180278395A1
• Time in Patent Office: 774 Days
• Field of Search: 370252
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26132 using repetition
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• 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 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

Methods, apparatuses, and systems described herein generally relate to a reference signal generation and mapping. For example, a method comprises determining a first set of antenna ports for a demodulation reference signal (DM-RS) transmission; determining, based on the first set, a frequency index associated with four adjacent resource elements, wherein the four adjacent resource elements correspond to two adjacent symbols in a time axis and to two adjacent subcarriers in a frequency axis; generating, based on a first orthogonal cover code and a second orthogonal cover code, a DM-RS associated with the first set of antenna ports; and transmitting, via a mapping to the four adjacent resource elements, the DM-RS associated with the first set of antenna ports.

Claims

1. A method comprising:

determining a first set, a second set, and a third set, of antenna ports, for a demodulation reference signal (DM-RS) transmission, wherein a first code division multiplexing (CDM) group comprises the first set of antenna ports, a second CDM group comprises the second set of antenna ports, and a third CDM group comprises the third set of antenna ports;

determining, for the first CDM group, a first frequency index associated with first adjacent resource elements, wherein the first adjacent resource elements correspond to two adjacent symbols in a time axis and to first two adjacent subcarriers in a frequency axis;

determining, for the second CDM group, a second frequency index associated with second adjacent resource elements, wherein the second adjacent resource elements correspond to the two adjacent symbols in the time axis and to second two adjacent subcarriers in the frequency axis;

determining, for the third CDM group, a third frequency index associated with third adjacent resource elements, wherein the third adjacent resource elements correspond to the two adjacent symbols in the time axis and to third two adjacent subcarriers in the frequency axis;

transmitting, based on orthogonal cover codes applied to the first adjacent resource elements, a DM-RS associated with the first set of antenna ports;

transmitting, based on the orthogonal cover codes applied to the second adjacent resource elements, a DM-RS associated with the second set of antenna ports; and

transmitting, based on the orthogonal cover codes applied to the third adjacent resource elements, a DM-RS associated with the third set of antenna ports,

wherein the orthogonal cover codes comprise at least one orthogonal cover code to be applied to two adjacent subcarriers.

2. The method of claim 1,

wherein each of the first, second, and third CDM groups comprises four different antenna ports.

3. The method of claim 1, wherein the first adjacent resource elements comprises a first resource element having a symbol index x and a subcarrier index y, a second resource element having a symbol index x and a subcarrier index (y+1), a third resource element having a symbol index (x+1) and a subcarrier index y, and a fourth resource element having a symbol index (x+1) and a subcarrier index (y+1) where x and y are positive integers, and

wherein a sequence of four orthogonal cover code values for the first resource element, the second resource element, the third resource element, and the fourth resource element is differently determined for each antenna port in the first set.

4. The method of claim 1, further comprising:

determining to transmit the DM-RSs via additional two adjacent symbols;

determining, for the first CDM group, the first frequency index associated with fourth adjacent resource elements, wherein the fourth adjacent resource elements correspond to the additional two adjacent symbols in the time axis and to the first two adjacent subcarriers in the frequency axis; and

transmitting, based on the orthogonal cover codes applied to the fourth adjacent resource elements, the DM-RS associated with the first set of antenna ports,

wherein at least one symbol exists between the two adjacent symbols and the additional two adjacent symbols, and

wherein the two adjacent symbols and the additional two adjacent symbols are comprised in one slot.

5. The method of claim 1, wherein the DM-RS associated with the first set of antenna ports comprises a DM-RS for a physical downlink shared channel (PDSCH), and

wherein the transmitting the DM-RS associated with the first set of antenna ports comprises transmitting, from a base station and to a user equipment, the DM-RS associated with the first set of antenna ports.

6. The method of claim 1, wherein the DM-RS associated with the first set of antenna ports comprises a DM-RS for a physical sidelink shared channel (PSSCH), and

wherein the transmitting the DM-RS associated with the first set of antenna ports comprises transmitting, from a user equipment and to another user equipment, the DM-RS associated with the first set of antenna ports.

7. The method of claim 1, wherein the DM-RS associated with the first set of antenna ports comprises a DM-RS for a physical uplink shared channel (PUSCH), and

wherein the transmitting the DM-RS associated with the first set of antenna ports comprises transmitting, from a user equipment and to a base station, the DM-RS associated with the first set of antenna ports.

8. The method of claim 1, wherein at least one of the first adjacent resource elements is adjacent to at least one of the second adjacent resource elements, and

wherein at least one of the second adjacent resource elements is adjacent to at least one of the third adjacent resource elements.

9. The method of claim 1, wherein at least one of the orthogonal cover codes is a length-2 orthogonal cover code associated with the first two adjacent subcarriers, the second two adjacent subcarriers, and the third two adjacent subcarriers.

10. A method comprising:

determining, by a base station, two adjacent orthogonal frequency division multiplexing (OFDM) symbols for mapping demodulation reference signals (DM-RSs) for at least three code division multiplexing (CDM) groups;

determining a first set, a second set, and a third set, of antenna ports, for a demodulation reference signal (DM-RS) transmission, wherein a first CDM group comprises the first set of antenna ports, a second CDM group comprises the second set of antenna ports, and a third CDM group comprises the third set of antenna ports;

determining, for the first CDM group, a first frequency index associated with first four adjacent resource elements, wherein the first four adjacent resource elements correspond to the two adjacent OFDM symbols in a time axis and to first two adjacent subcarriers in a frequency axis;

determining, for the second CDM group, a second frequency index associated with second four adjacent resource elements, wherein the second four adjacent resource elements correspond to the two adjacent OFDM symbols in the time axis and to second two adjacent subcarriers in the frequency axis;

determining, for the third CDM group, a third frequency index associated with third four adjacent resource elements, wherein the third four adjacent resource elements correspond to the two adjacent OFDM symbols in the time axis and to third two adjacent subcarriers in the frequency axis;

mapping, based on orthogonal cover codes applied to the first four adjacent resource elements, a first DM-RS to the first four adjacent resource elements, wherein the first DM-RS is associated with the first set of antenna ports;

mapping, based on the orthogonal cover codes applied to the second four adjacent resource elements, a second DM-RS to the second four adjacent resource elements, wherein the second DM-RS is associated with the second set of antenna ports; and

mapping, based on the orthogonal cover codes applied to the third four adjacent resource elements, a third DM-RS to the third four adjacent resource elements, wherein the third DM-RS is associated with the third set of antenna ports,

wherein the orthogonal cover codes comprise at least one orthogonal cover code to be applied to two adjacent subcarriers.

11. The method of claim 10, wherein the first set of antenna ports comprises one to four antenna ports not comprised in the second CDM group or the third CDM group, and

wherein the second set of antenna ports comprises one to four antenna ports not comprised in the first CDM group or the third CDM group.

12. The method of claim 10, wherein antenna ports in the second CDM group are configured to be selected for a DM-RS transmission after selecting at least one antenna port, from the first CDM group, for a DM-RS transmission, and

wherein antenna ports in the third CDM group are configured to be selected for a DM-RS transmission after selecting at least one antenna port, from the second CDM group, for a DM-RS transmission.

13. A method comprising:

receiving, by a user equipment (UE) and from a base station, a type of demodulation reference signal (DM-RS) configuration, a plurality of sets of antenna ports for DM-RS, and information indicating a quantity of code division multiplexing (CDM) groups scheduled for DM-RS transmission, wherein a first CDM group comprises a first set of the plurality of sets, and a second CDM group comprises a second set of the plurality of sets;

determining two adjacent symbols for mapping one or more DM-RSs;

determining, for the first CDM group, a first frequency index associated with first four adjacent resource elements, wherein the first four adjacent resource elements correspond to the two adjacent symbols in a time axis and to first two adjacent subcarriers in a frequency axis;

determining, for the second CDM group, a second frequency index associated with second four adjacent resource elements, wherein the second four adjacent resource elements correspond to the two adjacent symbols in the time axis and to second two adjacent subcarriers in the frequency axis;

transmitting, based on orthogonal cover codes applied to the first four adjacent resource elements, a DM-RS associated with the first set of antenna ports; and

transmitting, based on the orthogonal cover codes applied to the second four adjacent resource elements, a DM-RS associated with the second set of antenna ports,

wherein the orthogonal cover codes comprise at least one orthogonal cover code to be applied to two adjacent subcarriers.

14. The method of claim 13, further comprising:

determining, based on the information indicating the quantity of CDM groups scheduled for DM-RS transmission, whether to map a physical uplink shared channel (PUSCH) to third four adjacent resource elements, wherein the third four adjacent resource elements correspond to the two adjacent symbols in the time axis and to third two adjacent subcarriers in the frequency axis.

15. The method of claim 13,

wherein the second set of the plurality of sets are configured to be selected for a DM-RS transmission after selecting at least one antenna port, from the first CDM group, for a DM-RS transmission.

16. The method of claim 14, further comprising:

determining that the quantity of CDM groups scheduled for DM-RS transmission corresponds to two or three,

wherein the determining whether to map the PUSCH to third four adjacent resource elements comprises;

determining not to map the PUSCH to the third four adjacent resource elements.

17. The method of claim 13, wherein each of the orthogonal cover codes is a length-2 orthogonal cover code, and

wherein a combination of the orthogonal cover codes is applied to the first four adjacent resource elements and is applied to the second four adjacent resource elements.

18. The method of claim 13, wherein a first value of a first orthogonal cover code of the orthogonal cover codes is associated with a first one of the first two adjacent subcarriers, and

wherein a second value of the first orthogonal cover code of the orthogonal cover codes is associated with a second one of the first two adjacent subcarriers.

19. The method of claim 13, wherein one of 12 antenna ports is indicated based on information of a CDM group and the orthogonal cover codes, and

wherein the CDM groups are configured based on a frequency division multiplexing (FDM) scheme.

20. The method of claim 18, wherein the first value of the first orthogonal cover code is associated with a first one of the second two adjacent subcarriers, and

wherein the second value of the first orthogonal cover code is associated with a second one of the second two adjacent subcarriers.

21. The method of claim 13, wherein a first value of a second orthogonal cover code of the orthogonal cover codes is associated with a first one of the two adjacent symbols, and

wherein a second value of the second orthogonal cover code of the orthogonal cover codes is associated with a second one of the two adjacent symbols.