Beam management solution for MPE
Apparatuses, systems, and methods for a user equipment device (UE) to perform methods for triggering a change in beam configuration based on UL beam conditions. The UE may detect an unsafe UL beam condition for an UL beam based, at least in part, on an MPE level being exceeded by the UL beam. In response to the detection, remedial actions that to alleviate the unsafe UL beam condition may be performed. The remedial actions may prioritize UL beam quality over DL beam quality and may include reducing a transmit power of the UL beam based on an MPR, triggering an intra-panel antenna switch to a candidate UL beam that satisfies one or more conditions for intra-panel beam switching, triggering an inter-panel antenna switch to a candidate UL beam that satisfies one or more conditions for intra-panel beam switching, and/or signaling a beam failure to a network serving the UE.
1. A user equipment device (UE), comprising:
at least one antenna;
at least one radio, wherein the at least one radio is configured to perform cellular communication using at least one radio access technology (RAT);
one or more processors coupled to the at least one radio, wherein the one or more processors and the at least one radio are configured to perform voice and/or data communications;
wherein the one or more processors are configured to cause the UE to:
detect that a maximum possible exposure (MPE) level exceeds a threshold for at least one uplink (UL) beam; and
perform, based on detection of the MPE level exceeding the threshold, one or more remedial actions, wherein the one or more remedial actions prioritize UL beam quality over downlink (DL) beam quality, and wherein the one or more remedial actions include at least one of:
reducing a transmit power of the at least one UL beam based on a maximum power reduction (MPR);
triggering an intra-panel switch to a first candidate UL beam that satisfies one or more conditions for intra-panel beam switching;
triggering an inter-panel switch to a second candidate UL beam that satisfies one or more conditions for inter-panel beam switching; or
signaling a beam failure to a network serving the UE based on the unsafe UL beam condition.
2. The UE of claim 1 ,
wherein, to detect the unsafe UL beam condition, the one or more processors are further configured to cause the UE to determine one or more of:
a direction of the at least one UL beam relative to a user is unsafe for a transmission power of the at least one UL beam;
a position and/or orientation of the UE relative to the user is unsafe for the transmission power of the at least one UL beam; or
a transmission power level of the UE is unsafe based on the MPE level for an operating frequency range of the at least one UL beam.
3. The UE of claim 1 ,
wherein the one or more processors are further configured to cause the UE to:
report a power headroom to the network when a change in MPR exceeds a first threshold or when a value of the MPR exceeds a second threshold.
4. The UE of claim 3 ,
wherein the report of the power headroom is sent at an expiration of a timer associated with reporting the power headroom.
5. The UE of claim 4 ,
wherein a time associated with reporting the power headroom is specific to detection of unsafe UL beam conditions.
6. The UE of claim 3 ,
wherein the change in MPR is based on a current MPR and an MPR since last transmission of a power headroom report in a medium access control (MAC) entity for new transmissions.
7. The UE of claim 1 ,
wherein signaling the beam failure to the network serving the UE includes the UE comparing a UL beam quality measurement to an UL beam quality threshold, wherein beam failure is signaled when the UL beam quality measurement is less than the UL beam quality threshold.
8. The UE of claim 7 ,
wherein the UL beam quality measurement is based on a beam quality measurement less a power management maximum power reduction (P-MPR).
9. The UE of claim 7 ,
wherein the one or more processors are further configured to cause the UE to:
determine random access channel resources (RACH) based on the UL beam quality measurement.
10. An apparatus, comprising:
a memory; and
a processing element in communication with the memory, wherein the processing element is configured to:
detect an unsafe uplink (UL) beam condition for at least one UL beam based, at least in part, on a maximum possible exposure (MPE) level; and
perform, based on detection of the unsafe UL beam condition, one or more remedial actions to alleviate the unsafe UL beam condition, wherein the one or more remedial actions prioritize UL beam quality over downlink (DL) beam quality.
11. The apparatus of claim 10 ,
wherein the one or more remedial actions includes triggering an intra-panel switch to a first UL beam that satisfies one or more conditions for intra-panel beam switching, wherein the one or more conditions include at least one of:
a maximum power reduction (MPR) for the unsafe UL beam exceeding a first threshold;
a layer 1 (L1) reference signal received power (RSRP) with MPR reduction for the unsafe UL beam being less than a second threshold;
an L1-RSRP for the first UL beam exceeding a third threshold; or
an MPR for the first UL beam being less than a fourth threshold.
12. The apparatus of claim 11 ,
wherein the first, second, third, and fourth thresholds are predefined by a standard or configured via higher layer signaling with a network.
13. The apparatus of claim 11 ,
wherein switching to the first UL beam causes a beam pair mismatch with a network, and wherein to resolve the beam pair mismatch, the processing element is further configured to trigger a sounding reference signal (SRS) procedure for beam management or an L1-RSRP based beam reporting procedure.
14. The apparatus of claim 13 ,
wherein a request to trigger the SRS procedure or the L1-RSRP based beam reporting procedure is transmitted via at least one of a medium access control (MAC) control element (CE), a physical uplink control channel (PUCCH) transmission, or a contention based physical random access channel (PRACH) procedure.
15. The apparatus of claim 13 ,
wherein the processing element, as part of the SRS procedure, is further configured to generate instructions to transmit one or more of:
a synchronization signal block (SSB) resource index (SSBRI);
a channel state information reference signal (CSI-RS) resource index (CRI);
an SRS resource index (SRI) configured in a spatial relationship information element;
SRS resource indicator (SRI) for codebook/non-codebook;
a serving cell index; or
a bandwidth part index.
16. The apparatus of claim 13 ,
wherein the processing element, as part of the L1-RSRP based reporting procedure, is further configured to:
receive, from a network, an UL grant with a dedicated radio network temporary identifier (RNTI); and
report, to the network, L1-RSRP with MPR impact.
17. A non-transitory computer readable memory medium storing program instructions executable by processing circuitry to cause a user equipment device (UE) to:
detect an unsafe uplink (UL) beam condition for at least one UL beam based, at least in part, on a maximum possible exposure (MPE) level; and
perform, based on detection of the unsafe UL beam condition, one or more remedial actions to alleviate the unsafe UL beam condition, wherein the one or more remedial actions prioritize UL beam quality over downlink (DL) beam quality, and wherein the one or more remedial actions include at least one of:
reducing a transmit power of the at least one UL beam based on a maximum power reduction (MPR);
triggering an intra-panel switch to a first candidate UL beam that satisfies one or more conditions for intra-panel beam switching;
triggering an inter-panel switch to a second candidate UL beam that satisfies one or more conditions for inter-panel beam switching; or
signaling a beam failure to a network serving the UE based on the unsafe UL beam condition.
18. The non-transitory computer readable memory medium of claim 17 ,
wherein the one or more conditions for intra-panel beam switching includes at least one of:
a maximum power reduction (MPR) for the unsafe UL beam exceeding a first threshold;
a layer 1 (L1) reference signal received power (RSRP) with MPR reduction for the unsafe UL beam being less than a second threshold;
an L1-RSRP for the first UL beam exceeding a third threshold; or
an MPR for the first UL beam being less than a fourth threshold; and
wherein the first, second, third, and fourth thresholds are predefined by a standard or configured via higher layer signaling with a network.
19. The non-transitory computer readable memory medium of claim 17 ,
wherein, when the one or more remedial actions includes triggering an inter-panel switch to the second UL beam, the program instructions are further executable to cause the UE to:
perform a contention based physical random access control channel (PRACH) based procedure to switch a beam to pair with the second UL beam.
20. The non-transitory computer readable memory medium of claim 10 ,
wherein upon completion of the PRACH based procedure, the second UL beam and the DL beam are based on a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) identified by the PRACH based procedure.