METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING DEMODULATION REFERENCE SIGNAL

• US 20180278395A1
• Filed: 03/23/2018
• Published: 09/27/2018
• 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
• Granted Patent: US 10,644,849 B2
• Time in Patent Office: Days
• 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 of transmitting a reference signal, the method comprising:

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.

2. The method of claim 1, wherein the first orthogonal cover code is associated with the two adjacent subcarriers, and

wherein the second orthogonal cover code is associated with the two adjacent symbols.

3. The method of claim 1, further comprising:

determining three code division multiplexing (CDM) groups each comprising four different antenna ports,

wherein a first CDM group, of the three CDM groups, comprises the first set of antenna ports.

4. The method of claim 3, further comprising:

determining a second set of antenna ports for a DM-RS transmission;

determining, based on the second set, a frequency index associated with additional four adjacent resource elements, wherein the additional four adjacent resource elements correspond to the two adjacent symbols in the time axis and to additional two adjacent subcarriers in the frequency axis;

generating, based on the first orthogonal cover code and the second orthogonal cover code, a DM-RS associated with the second set of antenna ports; and

transmitting, via a mapping to the additional four adjacent resource elements, the DM-RS associated with the second set of antenna ports.

5. The method of claim 4, wherein the first orthogonal cover code is a length-2 orthogonal cover code and is associated with the two adjacent subcarriers, and

wherein the second orthogonal cover code is a length-2 orthogonal cover code and is associated with the two adjacent symbols.

6. The method of claim 5, wherein the four 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.

7. The method of claim 4, further comprising:

determining a third set of antenna ports for a DM-RS transmission;

determining, based on the third set, a frequency index associated with second additional four adjacent resource elements, wherein the second additional four adjacent resource elements correspond to the two adjacent symbols in the time axis and to second additional two adjacent subcarriers in the frequency axis;

generating, based on the first orthogonal cover code and the second orthogonal cover code, a DM-RS associated with the third set of antenna ports; and

transmitting, via a mapping to the second additional four adjacent resource elements, the DM-RS associated with the third set of antenna ports.

8. The method of claim 1, further comprising:

determining to transmit DM-RS via additional two adjacent symbols;

determining, based on the first set, the frequency index associated with additional four adjacent resource elements, wherein the additional four adjacent resource elements correspond to the additional two adjacent symbols in the time axis and to the two adjacent subcarriers in the frequency axis; and

transmitting, via a mapping to the additional four adjacent resource elements, a 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.

9. 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.

10. 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.

11. 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.

12. A method of mapping a reference signal, the method comprising:

determining, by a base station, a type of demodulation reference signal (DM-RS) configuration;

determining two adjacent orthogonal frequency division multiplexing (OFDM) symbols for mapping DM-RSs for at least three code division multiplexing (CDM) groups;

determining a first set of antenna ports for a demodulation reference signal (DM-RS) transmission to a first user equipment (UE), wherein a first CDM group, among the at least three CDM groups, comprises the first set of antenna ports;

determining, based on the first set, a 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; and

mapping, based on a first orthogonal cover code and a second orthogonal cover code, 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.

13. The method of claim 12, further comprising:

determining a second set of antenna ports for a DM-RS transmission to a second UE, wherein a second CDM group, among the at least three CDM groups, comprises the second set of antenna ports;

determining, based on the second set, a 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; and

mapping, based on the first orthogonal cover code and the second orthogonal cover code, 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.

14. The method of claim 12, further comprising:

determining a second set of antenna ports for a DM-RS transmission to the first UE, wherein a second CDM group, among the at least three CDM groups, comprises the second set of antenna ports;

determining, based on the second set, a 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; and

mapping, based on the first orthogonal cover code and the second orthogonal cover code, 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.

15. The method of claim 14, wherein the first set of antenna ports comprises one to four antenna ports not comprised in the second CDM group or a third CDM group of the at least three CDM groups, 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.

16. The method of claim 15, 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.

17. A method of transmitting a reference signal, the method comprising:

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

determining two adjacent symbols for mapping a DM-RS;

determining, based on the first set, a 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;

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 first four adjacent resource elements, the DM-RS associated with the first set of antenna ports.

18. The method of claim 17, further comprising:

determining, based on the information indicating a quantity of CDM groups scheduled for a DM-RS transmission, whether to map a physical uplink shared channel (PUSCH) to 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 a frequency axis.

19. The method of claim 18, wherein a first CDM group, among three CDM groups, comprises the first set of antenna ports,

wherein antenna ports in a second CDM group, among the three CDM groups, 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 a third CDM group, among the three CDM groups, 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.

20. The method of claim 19, further comprising:

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

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

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