Measurement gaps for L1 measurements
This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media for a user equipment (UE), which may include a reduced capability (RedCap) UE, and a supporting cell. The UE may receive a synchronization signal block (SSB). The UE may receive a configuration of an active downlink bandwidth part (BWP) that is not configured with a SSB. The UE may tune, from the active downlink BWP to a different frequency for a layer 1 (L1) measurement gap defined by a L1 measurement gap configuration. The UE may perform a L1 measurement of the SSB on the different frequency during the L1 measurement gap. The UE may be a RedCap UE, the active BWP may be for RedCap UEs, and the SSB may define an initial BWP for the RedCap UEs and non-RedCap UEs, and the different frequency may be the initial BWP.
1. A method comprising, at a user equipment (UE):
receiving a synchronization signal block (SSB);
receiving a configuration of an active downlink bandwidth part (BWP) that is not configured with a SSB;
tuning, from the active downlink BWP to a different frequency for a layer 1 (L1) measurement gap defined by a L1 measurement gap configuration; and
performing a L1 measurement of the SSB on the different frequency during the L1 measurement gap.
2. The method of claim 1 , wherein the L1 measurement gap configuration defines a measurement gap length (MGL) and a measurement gap repetition period (MGRP).
3. The method of claim 2 , wherein the MGL for the L1 measurement gap is less than a MGL of a layer 3 measurement gap.
4. The method of claim 2 , wherein the MGL of the L1 measurement gap is at least a number of configured L1 measurement resources times a slot length plus two times a radio-frequency tuning time.
5. The method of claim 2 , wherein the MGRP is an integer multiple of a transmission period of the SSB.
6. The method of claim 1 , further comprising receiving a radio resource control (RRC) message defining the L1 measurement gap configuration, wherein the RRC message includes a gap offset that aligns a layer 3 (L3) measurement gap to include the L1 measurement gap whenever there is an overlap between the L3 measurement gap and the L1 measurement gap.
7. The method of claim 6 , further comprising performing an intra-frequency L3 measurement based on the SSB concurrently with the L1 measurement.
8. The method of claim 6 , further comprising performing an inter-frequency or inter-RAT L3 measurement during the layer 3 measurement gap outside of the L1 measurement gap.
9. The method of claim 1 , wherein a downlink radio quality assessment period is defined based on the L1 measurement gap configuration.
10. The method of claim 9 , wherein the downlink radio quality assessment period is defined based on a multi-layer sharing factor (P) when there are L3 measurement gaps configured for intra-frequency, inter-frequency, or inter-RAT measurements and measurement resources configured for inter-frequency or inter-RAT measurements exist in the L3 measurement gaps, and there are L1 measurement gaps configured for SSB based RLM reference signal (RLM-RS) resources and some but not all of the L1 measurement gaps are overlapping with layer 3 measurement gaps.
11. The method of claim 9 , wherein the downlink radio quality assessment period is one of:
an RLM out-of-sync evaluation period;
an RLM in-sync evaluation period;
an evaluation period for beam failure detection that is defined in terms of a L1 MGRP;
a L1 indication period for Beam Failure Detection (BFD) where an SSB periodicity (TSSB-RS,M) refers to a shortest periodicity of all SSB-RS resources in a set q 0 that lie in the configured L1 measurement gap; or
an evaluation period for Candidate Beam Detection (CBD) that is defined in terms of periodicity of SSBs in a set q1 that lie in the configured L1 measurement gap.
12. The method of claim 1 , wherein a L1 reference signal received power (RSRP) measurement period is defined in terms of a periodicity of an SSB index that lies in the configured L1 measurement gap.
13. The method of claim 1 , wherein the UE is a reduced capability (RedCap) UE, the active BWP is for RedCap UEs, and the SSB is for RedCap UEs and non-RedCap UEs.
14. The method of claim 13 , wherein the SSB defines an initial BWP for the RedCap UEs and the non-RedCap UEs, and wherein the different frequency is the initial BWP.
15. A method comprising, at a base station:
transmitting a synchronization signal block (SSB);
transmitting, to at least one user equipment (UE), a configuration of an active downlink BWP that is not configured with a SSB; and
transmitting, to the at least one UE, a layer 1 (L1) measurement gap configuration defining a L1 measurement gap during which the at least one UE is to perform a L1 measurement of the SSB on a different frequency than the active downlink BWP.
16. The method of claim 15 , wherein the L1 measurement gap configuration defines a measurement gap length (MGL) and a measurement gap repetition period (MGRP).
17. The method of claim 16 , wherein the MGL for the L1 measurement gap is less than a MGL of a layer 3 (L3) measurement gap.
18. The method of claim 16 , wherein the MGL of the L1 measurement gap is at least a number of configured L1 measurement resources times a slot length plus two times a radio-frequency tuning time.
19. The method of claim 16 , wherein the MGRP is an integer multiple of a transmission period of the SSB.
20. The method of claim 16 , wherein transmitting the L1 measurement gap configuration comprises transmitting a radio resource control (RRC) message defining the L1 measurement gap configuration, wherein the RRC message includes a gap offset that aligns a L3 measurement gap to include the L1 measurement gap.
21. The method of claim 15 , wherein a radio link measurement (RLM) period is defined based on the L1 measurement gap configuration.
22. The method of claim 21 , wherein the RLM period is defined based on a multi-layer sharing factor (P) when there are L3 measurement gaps configured for intra-frequency, inter-frequency or inter-RAT measurements and measurement resources configured for inter-frequency or inter-RAT measurements exist in the L3 measurement gaps, and there are L1 measurement gaps configured for SSB based RLM reference signal (RLM-RS) resources and the L1 measurement gaps are overlapping with some but not all L3 measurement gaps.
23. The method of claim 21 , wherein the RLM period is one of:
an RLM out-of-sync evaluation period;
an RLM in-sync evaluation period;
an evaluation period for beam failure detection that is defined in terms of an L1 MGRP;
a L1 indication period for Beam Failure Detection (BFD) where an SSB periodicity (TSSB-RS,M) refers to a shortest periodicity of all SSB-RS resources in a set q0 that lie in the configured L1 measurement gap; or
an evaluation period for Candidate Beam Detection (CBD) that is defined in terms of periodicity of SSBs in a set q1 that lie in the configured L1 measurement gap.
24. The method of claim 15 , wherein a L1 reference signal received power (RSRP) measurement period is defined in terms of a periodicity of an SSB index that lies in the configured L1 measurement gap.
25. The method of claim 15 , wherein the at least one UE is a reduced capability (RedCap) UE, the active BWP is for RedCap UEs, and the SSB is for RedCap UEs and non-RedCap UEs.
26. An apparatus for wireless communication, comprising:
a transceiver;
a memory storing computer-executable instructions; and
a processor coupled with the transceiver and the memory and configured to:
execute the computer-executable instructions to:
receive a synchronization signal block (SSB);
receive a configuration of an active downlink bandwidth part (BWP) that is not configured with an SSB;
tune, from the active downlink BWP to a different frequency for a layer 1 (L1) measurement gap defined by a L1 measurement gap configuration; and
perform a L1 measurement of the SSB on the different frequency during the L1 measurement gap.
27. The apparatus of claim 26 , wherein the L1 measurement gap configuration defines a measurement gap length (MGL) and a measurement gap repetition period (MGRP).
28. The apparatus of claim 26 , wherein the processor is configured to execute the instructions to:
receive a radio resource control (RRC) message defining the L1 measurement gap configuration, wherein the RRC message includes a gap offset that aligns a layer 3 (L3) measurement gap to include the L1 measurement gap whenever there is an overlap between the L3 measurement gap and the L1 measurement gap; and
perform an intra-frequency L3 measurement based on the SSB concurrently with the L1 measurement.
29. The apparatus of claim 26 , wherein the apparatus is a reduced capability (RedCap) UE, the active BWP is for RedCap UEs, and the SSB defines an initial BWP for the RedCap UEs and non-RedCap UEs, and wherein the different frequency is the initial BWP.
30. An apparatus for wireless communication, comprising:
a transceiver;
a memory storing computer-executable instructions; and
a processor coupled with the transceiver and the memory and configured to execute the computer-executable instructions to:
transmit a synchronization signal block (SSB);
transmit, to at least one UE, a configuration of an active downlink BWP for UEs that is not configured with a SSB; and
transmit, to the at least one UE, a layer 1 (L1) measurement gap configuration defining a L1 measurement gap during which the at least one UE is to perform a L1 measurement of the SSB on a different frequency than the active downlink BWP.