System and method for UE triggered CSI-RS
Disclosed are systems, methods, and one or more computer-readable media (CRM) storing instructions for the triggering of a channel state information reference signal (CSI-RS) by user equipment (UE) in a wireless cellular network. The UE measures a downlink reference signal. The UE also determines a condition for triggering a channel state information reference signal (CSI-RS) is satisfied based on the downlink reference signal. Then, the UE transmits a request for a base station of the wireless cellular network to provide the CSI-RS to the UE based on the condition being satisfied.
1. A non-transitory computer-readable medium (CRM) comprising instructions that, when executed by one or more processors of a user equipment (UE) associated with a wireless cellular network, cause the UE to perform operations, the operations comprising:
measuring a downlink reference signal;
determining a condition for triggering a channel state information reference signal (CSI-RS) is satisfied based on the downlink reference signal; and
transmitting a request for a base station of the wireless cellular network to provide the CSI-RS to the UE based on the condition being satisfied,
wherein the request comprises a quasi-co-locate (QCL) source of the CSI-RS, a number of requested CSI-RS resources, a component carrier (CC) index, and a bandwidth part (BWP) index.
2. The non-transitory CRM of claim 1 , wherein the downlink reference signal is configured in active Transmission Configuration Indication (TCI) state for a Physical Downlink Shared Channel (PDSCH) or a control resource set (CORESET).
3. The non-transitory CRM of claim 1 , wherein the condition comprises a quality metric associated with the downlink reference signal being less than a threshold.
4. The non-transitory CRM of claim 1 , wherein determining the condition for triggering the CSI-RS is satisfied comprises determining that a difference between a quality metric associated with the downlink reference signal received using a current UE beam and a quality metric associated with the downlink reference signal received using a wide beam being less than a threshold.
5. The non-transitory CRM of claim 4 , wherein the quality metric is based on at least one of: layer 1 reference signal receiving power (L1-RSRP), layer 1 signal-to-interference plus noise (L1-SINR), hypothetical block error rate (BLER), or channel quality indicator (CQI).
6. The non-transitory CRM of claim 1 , wherein the QCL source of the CSI-RS is the downlink reference signal being measured, or a Transmission Configuration Indication (TCI) state configured by either a radio resource control (RRC), or a MAC control element (CE).
7. The non-transitory CRM of claim 1 , wherein the request is transmitted using a Physical Uplink Control Channel (PUCCH) configured in format 2, format 3, or format 4.
8. The non-transitory CRM of claim 1 , wherein the transmitting the request further comprises transmitting a scheduling request (SR) using at least one of: a Physical Uplink Control Channel (PUCCH) resource or a Physical Random Access Channel (PRACH) resource.
9. The non-transitory CRM of claim 1 , wherein the request is transmitted using a Physical Uplink Shared Channel (PUSCH) and a MAC control element (CE).
10. The non-transitory CRM of claim 1 , wherein the operations further comprise:
determining an uplink grant has not been received within N slots after determining that the condition is satisfied,
wherein the request is transmitted using a 2-step Random Access Channel (RACH) procedure in response to the uplink grant not having been received.
11. The non-transitory CRM of claim 1 , wherein the operations further comprise:
determining that an uplink grant has not been received within N slots after determining the condition is satisfied;
determining that the UE is not configured for a 2-step Random Access Channel (RACH) procedure;
transmitting a scheduling request to the base station in response to determining that the uplink grant has not been received and the UE is not configured for the 2-step RACH procedure; and
receiving an uplink grant after the scheduling request is transmitted,
wherein the request is transmitted via a physical uplink shared channel (PUSCH) after the uplink grant is received.
12. A method for operating a base station in a wireless cellular network, comprising:
receiving a request for a channel state information reference signal (CSI-RS) from a user equipment (UE) in the wireless cellular network; and
triggering the CSI-RS in response to the request,
wherein the request comprises a quasi-co-locate (QCL) source of the CSI-RS, a number of requested CSI-RS resources, a component carrier (CC) index, and a bandwidth part (BWP) index.
13. The method of claim 12 , wherein the request is received using a Physical Uplink Control Channel (PUCCH) configured in format 2, format 3, or format 4.
14. The method of claim 12 , wherein receiving the request comprises receiving a scheduling request (SR) using at least one of: a Physical Uplink Control Channel (PUCCH) resource or a Physical Random Access Channel (PRACH) resource.
15. The method of claim 12 , further comprising:
transmitting a message associated with contention resolution,
wherein the request is associated with a 2-step Random Access Channel (RACH) procedure.
16. A user equipment (UE) comprising:
radio front end circuitry configured to receive, from a radio access network node, first control signaling, the first control signaling indicating a wake up command; and
processor circuitry, coupled to the radio front end circuitry, the processor circuitry configured to:
measure a downlink reference signal;
determine a condition for triggering a channel state information reference signal (CSI-RS) is satisfied based on the downlink reference signal; and
transmit a request for a base station of a wireless cellular network to provide the CSI-RS to the UE based on the condition being satisfied,
wherein the request comprises a quasi-co-locate (QCL) source of the CSI-RS, a number of requested CSI-RS resources, a component carrier (CC) index, and a bandwidth part (BWP) index.
17. The UE of claim 16 , wherein:
determining the condition for triggering the CSI-RS is satisfied comprises determining that a difference between a quality metric associated with the downlink reference signal received using a current UE beam and a quality metric associated with the downlink reference signal received using a wide beam being less than a threshold, and
the quality metric is based on at least one of: layer 1 reference signal receiving power (L1-RSRP), layer 1 signal-to-interference plus noise (L1-SINR), hypothetical block error rate (BLER), or channel quality indicator (CQI).
18. The UE of claim 16 , wherein the request is transmitted using a 2-step Random Access Channel (RACH) procedure in response to an uplink grant not having been received.