Method and apparatus for CSI-RS in RRC_IDLE/inactive state

1. A user equipment (UE) comprising:

a transceiver configured to receive:

by a system information block (SIB), a first configuration for periodic channel state information reference signal/tracking reference signal (CSI-RS/TRS) reception occasions for idle/inactive UEs, wherein a periodic CSI-RS/TRS reception occasion includes one or more CSI-RS resources,

a second configuration for a paging occasion (PO), and

a third configuration of physical downlink control channel (PDCCH) reception occasions, wherein a PDCCH provides a downlink control information (DCI) format that includes one or more availability indication bits for respective one or more periodic CSI-RS/TRS reception occasions from the periodic CSI-RS reception occasions; and

a processor operably connected to the transceiver, the processor configured to determine reception in a first periodic CSI-RS/TRS occasion based on a value of a respective first availability indication bit,

wherein the transceiver is further configured to receive in the first periodic CSI-RS/TRS occasion based on the determination.

2. The UE of claim 1 , wherein the processor is further configured to determine a time duration, wherein an availability indication associated with the one or more availability indication bits expires by the time duration after a reception of the DCI format.

3. The UE of claim 1 , wherein the processor is further configured to determine a CSI-RS resource in the periodic CSI-RS/TRS reception occasions is:

a TRS, or

a CSI-RS, wherein the CSI-RS has at least one of following predetermined parameters:

a density, wherein the density is same as a TRS or has a predetermined value,

a number of antenna ports, wherein the number of antenna ports is one, and

a code division multiplexing (CDM) type, wherein no CDM is used for the CSI-RS.

4. The UE of claim 1 , wherein the first configuration includes a value for at least one of following parameters for a CSI-RS resource in the periodic CSI-RS/TRS reception occasions:

a power offset of a resource element (RE) for the CSI-RS resource to a RE for a secondary synchronization signal (SSS),

a scrambling identity (ID),

a bitmap to indicate one or more first orthogonal frequency-division multiplexing (OFDM) symbols in a slot,

a starting resource block (RB) to indicate a lowest RB index, and

a number of occupied RBs.

5. The UE of claim 1 , wherein:

the transceiver is further configured to receive a fourth configuration for a burst of synchronization signals/physical broadcast channel (SS/PBCH) blocks; and

the processor is further configured to determine:

a downlink (DL) bandwidth part (BWP) for receiving the burst of SS/PBCH blocks, and

a frequency location of a CSI-RS resource in the periodic CSI-RS/TRS reception occasions as:

being within a bandwidth (BW) of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a first RB of the DL BWP with a lowest index, or

not being restricted by the BW of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a common RB with an index 0.

6. The UE of claim 5 , wherein the processor is further configured to determine a spatial reception parameter for the CSI-RS resource in the periodic CSI-RS/TRS reception occasions is same as a spatial reception parameter for a SS/PBCH block in the burst of SS/PBCH blocks.

7. The UE of claim 5 , wherein the processor is further configured to determine a sub-carrier spacing (SCS) for the periodic CSI-RS/TRS reception occasions is:

same as a SCS of a DL BWP for receiving the burst of SS/PBCH blocks, or

provided by the first configuration.

8. A base station (BS) comprising:

a transceiver configured to transmit:

by a system information block (SIB), a first configuration for periodic channel state information reference signal/tracking reference signal (CSI-RS/TRS) transmission occasions for idle/inactive UEs, wherein a periodic CSI-RS/TRS transmission occasion includes one or more CSI-RS resources,

a second configuration for a paging occasion (PO), and

a third configuration of physical downlink control channel (PDCCH) transmission occasions, wherein a PDCCH provides a downlink control information (DCI) format that includes one or more availability indication bits for respective one or more periodic CSI-RS/TRS transmission occasions from the periodic CSI-RS transmission occasions; and

a processor operably connected to the transceiver, the processor configured to determine transmission in a first periodic CSI-RS/TRS occasion based on a value of a respective first availability indication bit,

wherein the transceiver is further configured to transmit the first periodic CSI-RS/TRS occasion based on the determination.

9. The BS of claim 8 , wherein the processor is further configured to determine a time duration, wherein an availability indication associated with the one or more availability indication bits expires by the time duration after a transmission of the DCI format.

10. The BS of claim 8 , wherein a CSI-RS resource in the periodic CSI-RS/TRS transmission occasions is:

a TRS, or

a CSI-RS, wherein the CSI-RS has at least one of following predetermined parameters:

a density, wherein the density is same as a TRS or has a predetermined value,

a number of antenna ports, wherein the number of antenna ports is one, and

a code division multiplexing (CDM) type, wherein no CDM is used for the CSI-RS.

11. The BS of claim 8 , wherein the first configuration includes a value for at least one of following parameters for a CSI-RS resource in the periodic CSI-RS/TRS transmission occasions:

a power offset of a resource element (RE) for the CSI-RS resource to a RE for a secondary synchronization signal (SSS),

a scrambling identity (ID),

a bitmap to indicate one or more first orthogonal frequency-division multiplexing (OFDM) symbols in a slot

a starting resource block (RB) to indicate a lowest RB index, and

a number of occupied RBs.

12. The BS of claim 8 , wherein:

the transceiver is further configured to transmit a fourth configuration for a burst of synchronization signals/physical broadcast channel (SS/PBCH) blocks; and

the processor is further configured to determine:

a downlink (DL) bandwidth part (BWP) for transmitting the burst of SS/PBCH blocks, and

a frequency location of a CSI-RS resource in the periodic CSI-RS/TRS transmission occasions as:

being within a bandwidth (BW) of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a first RB of the DL BWP with a lowest index, or

not being restricted by the BW of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a common RB with an index 0.

13. The BS of claim 12 , wherein the processor is configured to determine a spatial transmission parameter for the CSI-RS resource in the periodic CSI-RS/TRS transmission occasions is same as a spatial transmission parameter for a SS/PBCH block in the burst of SS/PBCH blocks.

14. The BS of claim 12 , wherein the processor is further configured to determine a sub-carrier spacing (SCS) for the periodic CSI-RS/TRS transmission occasions is:

same as a SCS of a DL BWP for transmitting the burst of SS/PBCH blocks, or

provided by the first configuration.

15. A method comprising:

receiving, by a system information block (SIB), a first configuration for periodic channel state information reference signal/tracking reference signal (CSI-RS/TRS) reception occasions for idle/inactive UEs, wherein a periodic CSI-RS/TRS reception occasion includes one or more CSI-RS resources;

receiving a second configuration for a paging occasion (PO);

receiving a third configuration of physical downlink control channel (PDCCH) reception occasions, wherein a PDCCH provides a downlink control information (DCI) format that includes one or more availability indication bits for respective one or more periodic CSI-RS/TRS reception occasions from the periodic CSI-RS reception occasions;

determining reception in a first periodic CSI-RS/TRS occasion based on a value of a respective first availability indication bit; and

receiving in the first periodic CSI-RS/TRS occasion based on the determination.

16. The method of claim 15 , further comprising determining a time duration, wherein an availability indication associated with the one or more availability indication bits expires by the time duration after a reception of the DCI format.

17. The method of claim 15 , further comprising determining a CSI-RS resource in the periodic CSI-RS/TRS reception occasions is:

a TRS, or

a CSI-RS, wherein the CSI-RS has at least one of following predetermined parameters:

a density, wherein the density is same as a TRS or has a predetermined value,

a number of antenna ports, wherein the number of antenna ports is one, and

a code division multiplexing (CDM) type, wherein no CDM is used for the CSI-RS.

18. The method of claim 15 , further comprising determining the first configuration includes a value for at least one of following parameters for a CSI-RS resource in the periodic CSI-RS/TRS reception occasions:

a power offset of a resource element (RE) for the CSI-RS resource to a RE for a secondary synchronization signal (SSS),

a scrambling identity (ID),

a bitmap to indicate one or more first orthogonal frequency-division multiplexing (OFDM) symbols in a slot,

a starting resource block (RB) to indicate a lowest RB index, and

a number of occupied RBs.

19. The method of claim 15 , further comprising:

receiving a fourth configuration for a burst of synchronization signals/physical broadcast channel (SS/PBCH) blocks;

determining a downlink (DL) bandwidth part (BWP) for receiving the burst of SS/PBCH blocks;

determining a frequency location of a CSI-RS resource in the periodic CSI-RS/TRS reception occasions as:

being within a bandwidth (BW) of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a first RB of the DL BWP with a lowest index, or

not being restricted by the BW of the DL BWP, wherein a starting RB of the CSI-RS resource is relative to a common RB with an index 0; and

determining a sub-carrier spacing (SCS) for the periodic CSI-RS/TRS reception occasions is:

same as a SCS of the DL BWP, or

provided by the first configuration.

20. The method of claim 19 , further comprising determining a spatial reception parameter for the CSI-RS resource in the CSI-RS/TRS reception occasions is same as a spatial reception parameter for a SS/PBCH block in the burst of SS/PBCH blocks.