RLM and beam failure detection based on a mix of different reference signals
A user equipment, UE, performs measurements based on a plurality of RLM sources received in beam-formed downlink signals, where the measurements indicate a quality of a given cell or beam. The plurality of sources comprises two or more of: first reference signals (RSs), second RSs of a different type than the first RSs, and one or more physical channel quality indicators obtained from non-reference-signal data in the beam-formed downlink signals. For each of the plurality of sources used to perform measurements, the UE determines whether a measurement for the respective source indicates an out-of-sync event in response to the measurement being below a first threshold. The UE then performs an RLM action based on determined occurrences of out-of-sync events.
1 . A method, in a user equipment (UE), the method comprising:
performing measurements based on each of a plurality of radio link management (RLM) measurement sources received in beam-formed downlink signals, wherein the plurality of RLM measurement sources comprises one or more first reference signals (RSs) and one or more second RSs of a different type than the first one or more RSs;
for each of a plurality of evaluation periods and for each RLM measurement source used to perform the measurements, determining whether a measurement for the respective RLM measurement source is below a first threshold;
performing one or more RLM actions based on said determining.
2 . The method of claim 1 , wherein the first and second RSs are channel-state information reference signals (CSI-RSs) and reference signals from one or more synchronization signal blocks (SSBs), respectively.
3 . The method of claim 1 , wherein performing the one or more RLM actions based on said determining comprises performing a first RLM action in response to determining that a threshold number of consecutive instances of the measurement being below the first threshold has occurred.
4 . The method of claim 3 , wherein the first RLM action comprises starting a timer.
5 . The method of claim 3 , wherein the first RLM action comprises one of: providing higher layer notifications; declaring radio link failure (RLF); and declaring beam failure.
6 . The method of claim 3 , wherein the threshold number is established separately for each source of the plurality of RLM measurement sources.
7 . The method of claim 3 , wherein the threshold number for one or more of the plurality of RLM measurement sources is shared by a different RLM measurement source.
8 . The method of claim 1 , wherein performing the measurements based on each of the plurality of RLM measurement sources comprises:
monitoring a control channel region of one or more of the beam-formed downlink signals and associated with a control channel message for the UE; and
in response to determining that data is scheduled in a given subframe of the control channel region:
determining, during an evaluation period, a first measurement by computing a first quality estimate using one or more first RSs, wherein the first RSs are demodulation reference symbols (DMRS) in the control channel region; and
determining, during the evaluation period, a second measurement by computing a second quality estimate using the one or more second RSs, wherein the one or more second RSs are one of: one or more primary synchronization signals (PSSs); one or more secondary synchronization signals (SSSs); one or more tertiary synchronization signals (TSSs); one or more DMRSs used for a physical broadcast channel (PBCH); one or more of channel state information-reference signals (CSI-RSs); one or more mobility reference signals (MRSs); and one or more beam measurement reference signals (BRSs).
9 . The method of claim 8 , wherein the first quality estimate is computed as an average of first radio signal metrics measured from the one or more first RSs over the evaluation period, and wherein the second quality estimate is computed as an average of second radio signal metrics measured from the one or more second RSs over the evaluation period.
10 . A user equipment (UE) comprising:
transceiver circuitry configured to receive beam-formed downlink signals; and
processing circuitry operatively associated with the transceiver circuitry and configured to:
perform measurements based on each of a plurality of radio link management (RLM) measurement sources received in beam-formed downlink signals, wherein each measurement indicates a quality of a given cell or beam, and wherein the plurality of RLM measurement sources comprises one or more first reference signals (RSs) and one or more second RSs of a different type than the first one or more RSs;
determine whether a measurement for the respective RLM measurement source is below a first threshold;
perform one or more RLM actions based on said determining.
11 . The UE of claim 10 , wherein the first and second RSs are channel-state information reference signals (CSI-RSs) and reference signals from one or more synchronization signal blocks (SSBs), respectively.
12 . The UE of claim 10 , wherein the processing circuitry is configured to perform the one or more RLM actions based on said determining by performing a first RLM action in response to determining that a threshold number of consecutive instances of the measurement being below the first threshold has occurred.
13 . The UE of claim 12 , wherein the first RLM action comprises starting a timer.
14 . The UE of claim 12 , wherein the first RLM action comprises one of: providing higher layer notifications; declaring radio link failure (RLF); and declaring beam failure.
15 . The UE of claim 12 , wherein the threshold number is established separately for each source of the plurality of RLM measurement sources.
16 . The UE of claim 12 , wherein the threshold number for one or more of the plurality of RLM measurement sources is shared by a different RLM measurement source.
17 . The UE of claim 10 , wherein the processing circuitry is configured to perform the measurements based on the plurality of RLM measurement sources by:
monitoring a control channel region of one or more of the beam-formed downlink signals and associated with a control channel message for the UE; and
in response to determining that data is scheduled in a given subframe of the control channel region:
determining, during an evaluation period, a first measurement by computing a first quality estimate using one or more first RSs, wherein the first RSs are demodulation reference symbols (DMRS) in the control channel region; and
determining, during the evaluation period, a second measurement by computing a second quality estimate using the one or more second RSs, wherein the one or more second RSs are one of: one or more primary synchronization signals (PSSs); one or more secondary synchronization signals (SSSs); one or more tertiary synchronization signals (TSSs); one or more DMRSs used for a physical broadcast channel (PBCH); one or more of channel state information-reference signals (CSI-RSs); one or more mobility reference signals (MRSs); and one or more beam measurement reference signals (BRSs).
18 . The UE of claim 17 , wherein the first quality estimate is computed as an average of first radio signal metrics measured from the one or more first RSs over the evaluation period, and wherein the second quality estimate is computed as an average of second radio signal metrics measured from the one or more second RSs over the evaluation period.
19 . The UE of claim 10 , wherein the processing circuitry is configured to:
receive configuration information for one or more of the plurality of RLM measurement sources; and
perform the measurements based on the configuration information.
20 . A non-transitory computer-readable medium comprising, stored thereupon, a computer program comprising computer program code that, when run on a user equipment (UE) causes the UE to:
perform measurements based on each of a plurality of radio link management (RLM) measurement sources received in beam-formed downlink signals, wherein the plurality of RLM measurement sources comprises one or more first reference signals (RSs) and one or more second RSs of a different type than the first one or more RSs;
determine whether a measurement for the respective RLM measurement source is below a first threshold;
perform one or more RLM actions based on said determining.