Method and apparatus for enhancing SRS flexibility, coverage, and capacity in a communication system

1. A base station apparatus for wireless communication with a user equipment (UE), the base station apparatus comprising:

a transceiver; and

a processor configured to:

transmit, to the LE, via the transceiver, a control message configured for the UE, and

receive, via the transceiver, a sounding reference signal (SRS) from the LTE, based on the control message,

wherein the control message indicates a triggering slot offset and an available slot to the UE for the SRS transmission, and

wherein the available slot satisfies the UE's capability on a minimum timing requirement between triggering a physical downlink control channel (PDCCH) and all SRS resources in a resource set.

2. The base station apparatus of claim 1 , wherein the control message utilizes a bitmap structure.

3. The base station apparatus of claim 1 , wherein the control message includes at least one of a radio resource control (RRC) message or a downlink control information (DCI) message.

4. The base station apparatus of claim 1 , wherein the processor is further configured to instruct the UE to consider all flexible slots as available slots, regardless of dynamic downlink scheduling.

5. The base station apparatus of claim 1 , wherein the processor is further configured to configure at least one bit field of a non-scheduling downlink control information (DCI) to indicate an aperiodic SRS triggering offset.

6. The base station apparatus of claim 5 , wherein the least one bit field comprises at least one of a frequency domain resource assignment field, a time domain resource assignment field, a modulation and coding scheme field, or an antenna port field in DCI format 0_1 or DCI format 1_1.

7. The base station apparatus of claim 1 , wherein the processor is further configured to configure the UE with an aperiodic (AP)-SRS-radio network temporary identifier (RNTI) via a radio resource control (RRC) configuration.

8. The base station apparatus of claim 1 , wherein the processor is further configured to, when at least two aperiodic SRS sets are triggered in a single downlink control information (DCI) message, generate the control message to include an SRS configuration information element including a dci-slotOffsetliD radio resource control (RRC) parameter.

9. The base station apparatus of claim 8 , wherein the processor is further configured to prioritize transmission of triggered AP-SRS sets in the bitmap structure, based on the dci-slotOffsoID.

10. The base station apparatus of claim 1 , wherein the processor is further configured to:

receive, via the transceiver, a UE capability message from the UE, and

generate the control message, based on the UE capability message.

11. The base station apparatus of claim 1 , wherein the processor is further configured to prioritize transmission of triggered aperiodic (AP)-SRS sets in the bitmap structure, based on an SRS set identifier.

12. The base station apparatus of claim 1 , wherein the processor is further configured to generate the control message to include an aperiodic (AP)-SRS command configuration information element that instructs the LiE to extract commands for flexible AP-SRS triggering from a group message.

13. A user equipment (UE) apparatus for wireless communication with a base station, the UE apparatus comprising:

a transceiver; and

a processor configured to:

receive, from the base station, via the transceiver, a control message configured for the UE, and

transmit, via the transceiver, a sounding reference signal (SRS) to the base station, based on the control message,

wherein the control message indicates a triggering slot offset and an available slot to the LIE for the SRS transmission, and

wherein the available slot satisfies the UE's capability on a minimum timing requirement between triggering a physical downlink control channel (PDCCH) and all SRS resources in a resource set.

14. The UE apparatus of claim 13 , wherein the control message utilizes a bitmap structure.

15. The UE apparatus of claim 13 , wherein the control message includes at least one of a radio resource control (RRC) message or a downlink control information (DCI) message.

16. The UE apparatus of claim 13 , wherein the processor is further configured to configure the UE to consider all flexible slots as available slots, regardless of dynamic downlink scheduling.

17. The UE apparatus of claim 13 , wherein at least one bit field of a non-scheduling downlink control information (DCI) of the control message indicates an aperiodic SRS triggering offset.

18. The UE apparatus of claim 17 , wherein the least one bit field comprises a at least one of frequency domain resource assignment field, a time domain resource assignment field, a modulation and coding scheme field, or an antenna port field in DCI format 0_1 or DCI format 1_1.

19. The UE apparatus of claim 13 , wherein the processor is further configured to identify an aperiodic (AP)-SRS-radio network temporary identifier (RNTI) via a radio resource control (RRC) configuration of the control message.

20. The UE apparatus of claim 13 , wherein the processor is further configured to, when at least two aperiodic SRS sets are triggered in a single downlink control information (DCI) message, identify an SRS configuration information element including a dci-slotOffsetID radio resource control (RRC) parameter in the control message.

21. The UE apparatus of claim 20 , wherein the processor is further configured to prioritize transmission of triggered AP-SRS sets in the bitmap structure, based on the dci-slotOffsetID.

22. The UE apparatus of claim 13 , wherein the processor is further configured to:

transmit, via the transceiver, a LE capability message to the base station, and

receive the control message generated, by the base station, based on the UE capability message.

23. The UE apparatus of claim 13 , wherein the processor is further configured to prioritize transmission of triggered aperiodic (AP)-SRS sets in the bitmap structure, based on an SRS set identifier.

24. The UE apparatus of claim 13 , wherein the processor is further configured to identify, in the control message, an aperiodic (AP)-SRS command configuration information element that instructs the UE to extract commands for flexible AP-SRS triggering from a group message.