Uplink reference signal transmissions during power saving operations
Methods, systems, and devices for wireless communications are described in which a user equipment (UE) may be configured for discontinuous reception (DRX) operations using wakeup signals. The UE may monitor periodic wakeup signal occasions for wakeup signals and, in the event that the UE detects a wakeup indication that the UE is to initiate an active duration, the UE may power on transmit/receive circuitry for communications with a base station. In an absence of receiving the wakeup indication, the UE may be configured to transmit an uplink reference signal (e.g., a sounding reference signal) to the base station in an inactive duration of a DRX cycle in some cases. The uplink reference signal may be measured at the base station and used to determine one or more parameters for subsequent communications with the UE.
1. A method for wireless communication at a user equipment (UE), comprising:
transmitting a capability indication that indicates that the UE is capable of uplink reference signal transmissions outside of an active duration of a discontinuous reception cycle;
monitoring a wakeup signal monitoring occasion in an inactive duration of the discontinuous reception cycle for a wakeup indication associated with a wakeup signal, wherein the active duration of the discontinuous reception cycle is initiated at the UE based at least in part on detection of the wakeup indication for the UE during the wakeup signal monitoring occasion; and
transmitting, based at least in part on an absence of the wakeup indication for the UE in the wakeup signal monitoring occasion, an uplink reference signal during a first time duration that is outside of an active duration of a first discontinuous reception cycle.
2. The method of claim 1 , further comprising:
receiving configuration information for a plurality of uplink reference signal resources for transmission of a plurality of uplink reference signals, and wherein the transmitting the uplink reference signal includes transmitting one or more uplink reference signals using a subset of the plurality of uplink reference signal resources.
3. The method of claim 2 , wherein the configuration information provides uplink reference signal resources for uplink reference signal transmissions within the active duration and provides separately configured uplink reference signal resources for uplink reference signal transmissions outside of the active duration.
4. The method of claim 2 , wherein the transmitting the uplink reference signal is based at least in part on a type of reference signal resource of the plurality of uplink reference signal resources that is present in the first time duration.
5. The method of claim 4 , wherein the type of reference signal resource includes one or more of a periodic sounding reference signal (SRS) resource, a semi-persistent SRS resource, an aperiodic SRS resource, SRS resources with periodicity larger than a threshold value, SRS resources configured with one or more usages, or any combinations thereof.
6. The method of claim 1 , further comprising:
transmitting, based at least in part on the absence of the wakeup indication for the UE in the wakeup signal monitoring occasion, a channel state information (CSI) report during the first time duration that is outside of the active duration of the first discontinuous reception cycle.
7. The method of claim 1 , wherein the uplink reference signal during the first time duration that is outside of the active duration of the first discontinuous reception cycle has one or more transmission parameters that are different than transmission parameters of uplink reference signals transmitted within the active duration of the first discontinuous reception cycle.
8. The method of claim 7 , wherein the one or more transmission parameters include one or more of a reference signal periodicity, number of antenna ports for reference signal transmission, a transmission power, a timing advance value, a set of time and frequency resources, or any combinations thereof, and wherein the one or more transmission parameters are determined based at least in part on a separate configuration or a predetermined rule associated with uplink reference signal transmissions during the first time duration that is outside of the active duration of the first discontinuous reception cycle.
9. The method of claim 1 , wherein the first time duration corresponds to a time duration of a discontinuous reception on-duration timer, a configured number of uplink reference signal transmission periods, or to a time duration that is different from the time duration of the discontinuous reception on-duration timer.
10. The method of claim 1 , further comprising:
monitoring, after the transmitting the uplink reference signal, for a downlink control channel transmission for a second time duration.
11. The method of claim 10 , wherein the downlink control channel transmission provides a transmit power control command for the UE that is based at least in part on the uplink reference signal.
12. The method of claim 10 , wherein the second time duration is a configured duration of time after the uplink reference signal transmission, a predetermined duration of time after the uplink reference signal transmission, a remaining duration of time until an end of the first time duration, or a zero-duration period that indicates no monitoring for the downlink control channel transmission.
13. A method for wireless communication at an access network entity, comprising:
receiving a capability indication that indicates that a user equipment (UE) is capable of uplink reference signal transmissions outside of an active duration of a discontinuous reception cycle;
configuring the UE for discontinuous reception operation with wakeup signal monitoring, wherein the active duration of the discontinuous reception cycle is initiated based at least in part on a wakeup indication that is transmitted during a wakeup signal monitoring occasion; and
receiving, in an absence of the wakeup indication being transmitted during the wakeup signal monitoring occasion, an uplink reference signal from the UE during a first time duration that is outside of an active duration of a first discontinuous reception cycle, wherein one or more parameters for communications with the UE are determined based at least in part on the uplink reference signal.
14. The method of claim 13 , wherein the configuring further comprises:
configuring a plurality of uplink reference signal resources for transmission of a plurality of uplink reference signals, and wherein the receiving the uplink reference signal includes receiving one or more uplink reference signals using a subset of the plurality of uplink reference signal resources.
15. The method of claim 14 , wherein the plurality of uplink reference signal resources provide uplink reference signal resources for uplink reference signal transmissions within the active duration and provides separately configured uplink reference signal resources for uplink reference signal transmissions outside of the active duration.
16. The method of claim 14 , wherein the receiving the uplink reference signal is based at least in part on a type of reference signal resource of the plurality of uplink reference signal resources that is present in the first time duration.
17. The method of claim 13 , further comprising:
receiving, in the absence of the wakeup indication being transmitted to the UE, a channel state information (CSI) report during the first time duration that is outside of the active duration of the first discontinuous reception cycle.
18. The method of claim 13 , wherein the uplink reference signal during the first time duration that is outside of the active duration of the first discontinuous reception cycle has one or more transmission parameters that are different than transmission parameters of uplink reference signals transmitted within active durations of one or more discontinuous reception cycles.
19. The method of claim 13 , wherein the first time duration corresponds to a time duration of a discontinuous reception on-duration timer, a configured number of uplink reference signal transmission periods, or to a time duration that is different from the time duration of the discontinuous reception on-duration timer.
20. The method of claim 13 , further comprising:
transmitting, after the receiving the uplink reference signal, a downlink control channel transmission to the UE during a second time duration, wherein the downlink control channel transmission provides a transmit power control command for the UE that is based at least in part on the uplink reference signal.
21. An apparatus for wireless communication at a user equipment (UE), comprising:
at least one processor;
memory coupled with the at least one processor; and
instructions stored in the memory and executable by the at least one processor to cause the UE to:
transmit a capability indication that indicates that the UE is capable of uplink reference signal transmissions outside of an active duration of a discontinuous reception cycle;
monitor a wakeup signal monitoring occasion in an inactive duration of the discontinuous reception cycle for a wakeup indication associated with a wakeup signal, wherein the active duration of the discontinuous reception cycle is initiated at the UE based at least in part on detection of the wakeup indication for the UE during the wakeup signal monitoring occasion; and
transmit, based at least in part on an absence of the wakeup indication for the UE in the wakeup signal monitoring occasion, an uplink reference signal during a first time duration that is outside of an active duration of a first discontinuous reception cycle.
22. The apparatus of claim 21 , wherein the instructions are further executable by the at least one processor to cause the UE to:
receive configuration information for a plurality of uplink reference signal resources for transmission of a plurality of uplink reference signals, and
transmit one or more uplink reference signals using a subset of the plurality of uplink reference signal resources.
23. The apparatus of claim 21 , wherein the instructions are further executable by the at least one processor to cause the UE to:
transmit, based at least in part on the absence of the wakeup indication for the UE in the wakeup signal monitoring occasion, a channel state information (CSI) report during the first time duration that is outside of the active duration of the first discontinuous reception cycle.
24. The apparatus of claim 21 , wherein the uplink reference signal during the first time duration that is outside of the active duration of the first discontinuous reception cycle has one or more transmission parameters that are different than transmission parameters of uplink reference signals transmitted within the active duration of the first discontinuous reception cycle.
25. The apparatus of claim 21 , wherein the first time duration corresponds to a time duration of a discontinuous reception on-duration timer, a configured number of uplink reference signal transmission periods, or to a time duration that is different from the time duration of the discontinuous reception on-duration timer.
26. The apparatus of claim 21 , wherein the instructions are further executable by the at least one processor to cause the UE to:
monitor, after transmission of the uplink reference signal, for a downlink control channel transmission for a second time duration.
27. An apparatus for wireless communication at an access network entity, comprising:
at least one processor;
memory coupled with the at least one processor; and
instructions stored in the memory and executable by the at least one processor to cause the access network entity to:
receive a capability indication that indicates that a user equipment (UE) is capable of uplink reference signal transmissions outside of an active duration of a discontinuous reception cycle;
configure the UE for discontinuous reception operation with wakeup signal monitoring, wherein the active duration of the discontinuous reception cycle is initiated based at least in part on a wakeup indication that is transmitted during a wakeup signal monitoring occasion; and
receive, in an absence of the wakeup indication being transmitted during the wakeup signal monitoring occasion, an uplink reference signal from the UE during a first time duration that is outside of an active duration of a first discontinuous reception cycle, wherein one or more parameters for communications with the UE are determined based at least in part on the uplink reference signal.
28. The apparatus of claim 27 , wherein the instructions to configure are further executable by the at least one processor to cause the access network entity to:
configure a plurality of uplink reference signal resources for transmission of a plurality of uplink reference signals, and
receive one or more uplink reference signals on a subset of the plurality of uplink reference signal resources.
29. The apparatus of claim 27 , wherein the instructions are further executable by the at least one processor to cause the access network entity to:
receive, in the absence of the wakeup indication being transmitted to the UE, a channel state information (CSI) report during the first time duration that is outside of the active duration of the first discontinuous reception cycle.
30. The apparatus of claim 27 , wherein the first time duration corresponds to a time duration of a discontinuous reception on-duration timer, a configured number of uplink reference signal transmission periods, or to a time duration that is different from the time duration of the discontinuous reception on-duration timer.