Method and apparatus for CSI-RS setting for beam management in wireless communication system

1. A method of determining a beam to be used for communication by a user equipment (UE) in a millimeter wave (mmWave) communication system, the method comprising:

receiving a synchronization signal (SS) block or a channel state information-reference signal (CSI-RS) from a base station (BS);

reporting a preferred primary beam based on the received SS block or CSI-RS to the BS;

receiving secondary beam information based on the preferred primary beam from the BS;

reporting a preferred secondary beam based on the secondary beam information to the BS;

changing the preferred primary beam based on the preferred primary beam and the preferred secondary beam not satisfying a threshold; and

transmitting a beam recovery signal for reporting a changed preferred primary beam to the BS based on an uplink resource being allocated by the BS,

wherein the UE is configured with a CSI-RS resource based on the preferred secondary beam by the BS, and

wherein the secondary beam information includes information about at least one secondary beam quasi-co-located (QCLed) with the preferred primary beam.

2. The method according to claim 1 , wherein a CSI-RS resource set is determined based on a primary beam, and a CSI-RS resource is determined based on a secondary beam.

3. The method according to claim 2 , wherein the preferred secondary beam is indicated by a CSI-RS resource index (CRI).

4. The method according to claim 1 , wherein information about the preferred primary beam and information about the preferred secondary beam are transmitted in at least one of a random access channel (RACH), a medium access control-control element (MAC-CE), or uplink data.

5. The method according to claim 1 , wherein the CSI-RS resource is mapped to a symbol and multiple CSI-RS ports,

wherein the preferred secondary beam is indicated by a CSI-RS resource index (CRI) and a CSI-RS port index.

6. The method according to claim 5 , wherein the multiple CSI-RS ports are multiplexed in at least one of frequency division multiplexing and time division multiplexing in the symbol.

7. The method according to claim 1 , wherein the UE receives changed secondary beam information based on the changed preferred primary beam from the BS, determines a changed preferred secondary beam based on the changed secondary beam information, reports the changed preferred secondary beam to the BS, and is configured with a changed CSI-RS resource based on the changed preferred secondary beam by the BS.

8. The method according to claim 7 , wherein the changed preferred second beam information includes information about at least one secondary beam QCLed with the changed primary beam.

9. The method according to claim 1 , wherein the primary beam corresponds to a wide beam or rough beam, and the secondary beam corresponds to a narrow beam or fine beam.

10. The method according to claim 1 , wherein the CSI-RS is a reference signal used for beam management, and corresponds to at least one of a measurement reference signal (MRS) or an SS block.

11. A user equipment (UE) for determining a beam to be sued for communication in a millimeter wave (mmWave) communication system, the UE comprising:

a receiver configured to receive a signal from an external device;

a transmitter configured to transmit a signal to an external device; and

a processor configured to control the receiver and the transmitter,

wherein the processor is configured to:

receive a synchronization signal (SS) block or a channel state information-reference signal (CSI-RS) from a base station (BS) through the receiver,

report a preferred primary beam based on the received SS block or CSI-RS to the BS through the transmitter,

receive secondary beam information based on the preferred primary beam from the BS through the receiver,

report a preferred secondary beam based on the secondary beam information to the BS through the transmitter,

change the preferred primary beam based on the preferred primary beam and the preferred secondary beam not satisfying a threshold, and

transmit a beam recovery signal for reporting a changed preferred primary beam to the BS through the transmitter based on an uplink resource being allocated by the BS,

wherein a CSI-RS resource is configured by the BS based on the preferred secondary beam, and

wherein the secondary beam information includes information about at least one secondary beam quasi-co-located (QCLed) with the preferred primary beam.

12. The UE according to claim 11 , wherein a CSI-RS resource set is determined based on a primary beam, and a CSI-RS resource is determined based on a secondary beam.

13. The UE according to claim 12 , wherein the preferred secondary beam is indicated by a CSI-RS resource index (CRI).

14. The UE according to claim 11 , wherein information about the preferred primary beam and information about the preferred secondary beam are transmitted in at least one of a random access channel (RACH), a medium access control-control element (MAC-CE), or uplink data.

15. The UE according to claim 11 , wherein the CSI-RS resource is mapped to a symbol and multiple CSI-RS ports,

wherein the preferred secondary beam is indicated by a CSI-RS resource index (CRI) and a CSI-RS port index.

16. The UE according to claim 15 , wherein the multiple CSI-RS ports are multiplexed in at least one of frequency division multiplexing and time division multiplexing in the symbol.

17. The UE according to claim 16 , wherein the processor is configured to receive changed preferred secondary beam information based on the changed primary beam from the BS through the receiver, to determine a changed secondary beam based on the changed preferred secondary beam information, to report the changed preferred secondary beam to the BS through the transmitter, and to be configured with a changed CSI-RS resource based on the changed preferred secondary beam by the BS.

18. The UE according to claim 17 , wherein the changed second beam information includes information about at least one secondary beam QCLed with the changed preferred primary beam.

19. The UE according to claim 11 , wherein the primary beam corresponds to a wide beam or rough beam, and the secondary beam corresponds to a narrow beam or fine beam.

20. The UE according to claim 11 , wherein the CSI-RS is a reference signal used for beam management, and corresponds to at least one of a measurement reference signal (MRS) or an SS block.