Patent Description:
Document <CIT> is directed to a method for beam failure recovery (BFR) by a user equipment (UE). The method includes receiving, by the UE, an instruction for BFR from a base station, and selecting, by the UE, at least one of a plurality of secondary cells (SCells) to perform BFR based on the instruction. The instruction is contained in a radio resource control (RRC) message, a medium access control (MAC) control element (CE) (MAC-CE), or downlink control information (DCI).

<CIT> relates to a UE providing beam management and method for beam recovery and beam management to be executed by the UE. The method for beam management comprises a beam failure detection, a beam reporting and a beam recovery. The present disclosure provides one or more methods for performing beam management and beam recovery when the UE is operating in multiple carriers.

There is disclosed a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and specification. The aspects of the invention include a method according to claim <NUM>, a program according to claim <NUM> and an apparatus according to claim <NUM>.

The wireless network <NUM> may include a number of BSs <NUM> (shown as BS 110a, BS 110b, BS 110c, and BS 11od) and other network entities.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with beam failure detection reference signal selection for secondary cells, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors of the base station <NUM> and/or the UE <NUM>, may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein.

In some aspects, UE <NUM> may include means for determining a set of beam failure detection reference signals to monitor for a set of secondary cells based at least in part on at least one of a cell configuration, a set of secondary cell reference signal selection rules, or a set of primary cell reference signal selection rules; means for monitoring the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals; means for detecting, based at least in part on monitoring the set of beam failure detection reference signals, a beam failure for a secondary cell of the set of secondary cells, and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of wireless communication via one or more beams, in accordance with certain aspects of the present disclosure.

As shown in <FIG>, a first apparatus <NUM> (e.g., shown as a UE, such as UE <NUM>, in example <NUM>) may communicate with a second apparatus <NUM> (e.g., shown as a BS, such as BS <NUM>, in example <NUM>) using one or more active beams <NUM>. In some aspects, the first apparatus <NUM> and the second apparatus <NUM> may also be capable of communicating via one or more candidate beams <NUM>. In some aspects, an active beam <NUM> may be selected from a set of candidate beams <NUM> by comparing beam parameters (e.g., RSRP, RSRQ, RSSI, and/or the like) of the set of candidate beams <NUM>. For example, an active beam <NUM> may be the beam that has the best beam parameters among all beams in the set of candidate beams <NUM>. In some aspects, the beams may operate in a millimeter wave radio frequency band.

In some aspects, if the active beam <NUM> experiences a failure, the first apparatus <NUM> may perform a beam failure recovery procedure. For example, upon detecting the failure of the active beam <NUM>, the first apparatus <NUM> may attempt to communicate with the second apparatus <NUM> by transmitting a beam failure recovery request (BFRQ) via one or more candidate beams <NUM>.

The first apparatus <NUM> may detect the failure based at least in part on monitoring one or more beam failure detection reference signals. For example, when first apparatus <NUM> determines that a measured RSRP of a beam failure detection reference signal satisfies a threshold, first apparatus <NUM> may determine that a beam failure has occurred. In some cases, second apparatus <NUM> may explicitly configure which beam failure detection reference signals, of a plurality of possible beam failure detection reference signals, first apparatus <NUM> is to monitor. For beams associated with a primary cell, when second apparatus <NUM> does not explicitly configure monitoring for first apparatus <NUM>, first apparatus <NUM> may determine the beam failure detection reference signals based at least in part on a set of primary cell reference signal selection rules.

<FIG> is a diagram illustrating an example <NUM> of a beam failure recovery procedure, in accordance with certain aspects of the present disclosure.

As shown in <FIG>, a BS <NUM> and a UE <NUM> may communicate with one another using carrier aggregation. Using carrier aggregation, BS <NUM> and UE <NUM> may communicate with one another using a primary cell (PCell) and one or more secondary cells (SCells). In example <NUM>, the secondary cells are DL-only secondary cells, meaning that the secondary cells are configured for only downlink communications, and are not configured for uplink communications. However, in some aspects, secondary cells may be configured for DL and UL, UL-only, DL-only, a combination thereof, and/or the like.

As shown by reference number <NUM>, UE <NUM> may detect beam failure on a DL-only secondary cell. For example, UE <NUM> may detect the beam failure by monitoring for a beam failure detection reference signal on the DL-only secondary cell, as described in more detail herein. As shown by reference number <NUM>, UE <NUM> and BS <NUM> may perform a beam failure recovery procedure using the primary cell. For example, the UE <NUM> may transmit a scheduling request on the primary cell via a physical uplink control channel (PUCCH). The scheduling request may trigger beam failure recovery (BFR), which may also be referred to as a link recovery procedure. Based at least in part on receiving the scheduling request, BS <NUM> may transmit, on the primary cell, a physical downlink shared channel (PDCCH) communication that schedules a PUCCH communication for BFR.

The UE <NUM> may receive the PDCCH communication, and may transmit the scheduled PUCCH communication on the primary cell. The PUCCH communication may identify the secondary cell that experienced the beam failure and/or may indicate a candidate beam index for a candidate beam to replace the failed beam. For example, the PUCCH communication may include a medium access control (MAC) control element (CE) (MAC-CE) that identifies the failed secondary cell and the replacement beam. Based at least in part on receiving the PUCCH communication, the base station <NUM> may transmit, on the primary cell, a PDCCH communication that instructs the UE <NUM> regarding the BFR procedure. For example, the PDCCH communication may instruct the UE <NUM> to perform a random access procedure for the secondary cell on one or more candidate beams. The UE <NUM> may perform BFR according to the PDCCH communication to obtain a new beam for communications on the secondary cell.

As described above, a UE may detect a beam failure by monitoring for a beam failure detection reference signal. In primary cell operation, the UE and a BS may configure up to <NUM> control resource sets (CORESETs) and up to <NUM> beam failure detection reference signals. However, in secondary cell operation, additional quantities of CORESETs and/or beam failure detection reference signals may be possible. Additionally, or alternatively, with secondary cell grouping enabled, a plurality of beam failure detection reference signals may share a common CORESET. As a result, primary cell reference signal selection rules may not be applicable to secondary cell beam failure detection reference signal selection use cases.

Thus, some aspects described herein enable beam failure detection reference signal selection for secondary cells. For example, a UE may determine a set of beam failure detection reference signals to monitor based at least in part on a cell configuration, a set of secondary cell reference signal selection rules, and/or a set of primary cell reference signal selection rules. Based at least in part on using the set of secondary cell reference signal selection rules, the UE enables secondary cell beam failure detection reference signal selection in cases where primary cell reference signal selection rules result in ambiguity when applied to secondary cells. In this way, the UE increases a reliability of communications with the BS relative to only detecting beam failures on primary cells using beam failure detection reference signals selected based at least in part on primary cell reference signal selection rules.

<FIG> is a diagram illustrating an example <NUM> of beam failure detection reference signal selection for secondary cells, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> includes a BS <NUM> and a UE <NUM>.

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> may determine beam failure detection reference signals to monitor. For example, UE <NUM> may identify one or more beam failure detection reference signals, of a set of possible beam failure detection reference signals, that UE <NUM> is to monitor to detect a beam failure.

In some aspects, UE <NUM> may select a particular quantity of beam failure detection reference signals. For example, UE <NUM> may determine a maximum quantity of beam failure detection reference signals, and may select up to the maximum quantity. In this case, the maximum quantity may be based at least in part on a quantity of secondary cells available to UE <NUM>. For example, UE <NUM> may enable selection of a single beam failure detection reference signal for each secondary cell. Additionally, or alternatively, UE <NUM> may enable selection of a particular quantity of beam failure detection reference signals for each secondary cell. Additionally, or alternatively, UE <NUM> may enable selection of beam failure detection reference signals for a particular portion of available secondary cells. In some aspects, UE <NUM> may determine the maximum quantity of beam failure detection reference signals based at least in part on a quantity of secondary cell groups. In some aspects, UE <NUM> may determine a maximum quantity for each secondary cell (e.g., up to a threshold amount of beam failure detection reference signals selected for each secondary cell), different maximum quantities for different secondary cells (e.g., a first maximum quantity for a first secondary cell and a second maximum quantity for a second secondary cell), a maximum quantity for each secondary cell group, and/or the like.

In some aspects, UE <NUM> may determine the maximum quantity based at least in part on a stored configuration, on received signaling from BS <NUM>, and/or the like. For example, UE <NUM> may determine the maximum quantity based at least in part on a stored configuration, and may provide a UE capability report to BS <NUM> indicating the maximum quantity, to enable BS <NUM> to determine the same quantity of beam failure detection reference signals for UE <NUM> as UE <NUM> is to determine. Additionally, or alternatively, BS <NUM> may determine the maximum quantity, or determine a different maximum quantity than is determined by UE <NUM>, and may transmit signaling to UE <NUM> to identify the maximum quantity that is determined by BS <NUM> or override the maximum quantity that is determined by UE <NUM>.

In some aspects, UE <NUM> may receive signaling from BS <NUM> identifying the set of beam failure detection reference signals. For example, BS <NUM> may determine a set of beam failure detection reference signals that UE <NUM> is to monitor, and may transmit control information to identify the set of beam failure detection reference signals.

In contrast, according to the claimed invention, when UE <NUM> does not receive signaling from BS <NUM> identifying the set of beam failure detection reference signals, UE <NUM> determines the set of beam failure detection reference signals based at least in part on a set of secondary cell reference signal selection rules. The UE <NUM> selects one or more beam failure detection reference signals, to monitor, that are quasi-co-located (QCL) (e.g., type-D QCL) with CORESETs of a secondary cell or secondary cell group to which UE <NUM> is connected. Additionally, or alternatively, UE <NUM> may select a beam failure detection reference signal of a secondary primary cell of a secondary cell group to which UE <NUM> is connected. Additionally, or alternatively, UE <NUM> may select beam failure detection reference signals of secondary cells in a secondary cell group in which a BFQR or physical uplink control channel (PUCCH) group is configured. Additionally, or alternatively, UE <NUM> may select beam failure reference signals of secondary cells in which UE <NUM> is configured to communicate with BS <NUM> (e.g., UL and DL secondary cells).

In some aspects, UE <NUM> may resolve a conflict between a plurality of beam failure detection reference signals that UE <NUM> can select to monitor (e.g., a plurality that is greater than the maximum quantity of beam failure detection reference signals that UE <NUM> can select to monitor). For example, UE <NUM> may determine that a quantity of qualified CORESETs is greater than a maximum quantity of beam failure detection reference signals, and may select a qualified CORESET from which to select a beam failure detection reference signal based at least in part on one or more selection criteria. In this case, UE <NUM> may use, as selection criteria, information such as a periodicity of a corresponding reference signal (e.g., of the qualified CORESET), a CORESET identifier (e.g., a value of a CORESET index), a secondary cell identifier (e.g., of a secondary cell to which the qualified CORESET applies), a secondary cell group identifier (e.g., of a secondary cell group that includes the secondary cell to which the qualified CORESET applies), a PUCCH resource periodicity (e.g., for a BFRQ configured for the qualified CORESET), and/or the like. Additionally, or alternatively, UE <NUM> may use, as selection criteria for resolving a conflict when using secondary cell reference signal selection rules, a primary cell reference signal selection rule.

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> may monitor the selected beam failure detection reference signals. For example, UE <NUM> may monitor one or more beam failure detection reference signals on one or more beams (e.g., secondary cell beams) to attempt to detect a beam failure when a beam failure occurs. In some aspects, UE <NUM> may perform one or more measurements when monitoring the one or more beam failure detection reference signals. For example, UE <NUM> may determine an RSRP, an RSRQ, and/or the like to determine whether a beam failure has occurred.

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> may detect a beam failure. For example, UE <NUM> may detect the beam failure on a monitored beam failure detection reference signal on a secondary cell beam. In some aspects, UE <NUM> may detect the beam failure based at least in part on detecting a threshold measurement. For example, UE <NUM> may determine that an RSRQ has satisfied a threshold and may determine that a beam failure has occurred. In this case, UE <NUM> may trigger a beam failure recovery procedure, such as by transmitting a BFRQ, as described above.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the UE (e.g., the first apparatus <NUM>, UE <NUM>, and/or the like) performs operations associated with beam failure detection reference signal selection for secondary cells.

As shown in <FIG>, in some aspects, process <NUM> may include determining a set of beam failure detection reference signals to monitor for a set of secondary cells based at least in part on at least one of a cell configuration, a set of secondary cell reference signal selection rules, or a set of primary cell reference signal selection rules (block <NUM>). For example, the UE (e.g., using controller/processor <NUM> and/or the like) may determine a set of beam failure detection reference signals to monitor for a set of secondary cells based at least in part on at least one of a cell configuration, a set of secondary cell reference signal selection rules, or a set of primary cell reference signal selection rules, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include monitoring the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals (block <NUM>). For example, the UE (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) may monitor the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include detecting, based at least in part on monitoring the set of beam failure detection reference signals, a beam failure for a secondary cell of the set of secondary cells (block <NUM>). For example, the UE (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) may detect, based at least in part on monitoring the set of beam failure detection reference signals, a beam failure for a secondary cell of the set of secondary cells, as described above.

In a first aspect, a quantity of beam failure detection reference signals in the set of beam failure detection reference signals is defined based at least in part on a size criterion.

In a second aspect, alone or in combination with the first aspect, the size criterion is determined on one of a per network basis, a per secondary cell group basis, or a per secondary cell basis.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes reporting the size criterion to a base station via a UE capability message.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process <NUM> includes receiving information identifying the size criterion from a base station.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process <NUM> includes determining the size criterion based on a stored configuration.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the set of secondary cells is a secondary cell group with a quasi-co-location relationship defining one or more shared beams or a shared frequency band.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, determining the set of beam failure detection reference signals includes determining that the cell configuration is configured for the UE and determining the set of beam failure detection reference signals using the cell configuration based at least in part on determining that the cell configuration is configured for the UE.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, determining the set of beam failure detection reference signals includes determining that the cell configuration is not configured for the UE and determining the set of beam failure detection reference signals using the set of secondary cell reference signal selection rules based at least in part on determining that the cell configuration is not configured for the UE.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, determining the set of beam failure detection reference signals using the set of secondary cell reference signal selection rules includes identifying a plurality of beam failure detection reference signals quasi-co-located with one or more CORESETs of the set of secondary cells and selecting the set of beam failure detection reference signals based at least in part on the plurality of beam failure detection reference signals.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, determining the set of beam failure detection reference signals using the set of secondary cell reference signal selection rules includes identifying a plurality of beam failure detection reference signals quasi-co-located with a CORESET of a secondary primary cell of the set of secondary cells and selecting the set of beam failure detection reference signals based at least in part on the plurality of beam failure detection reference signals.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, determining the set of beam failure detection reference signals using the set of secondary cell reference signal selection rules includes identifying a plurality of beam failure detection reference signals quasi-co-located with one or more CORESETs of one or more cells of the set of secondary cells in which a beam failure recover request or physical uplink control channel group is configured and selecting the set of beam failure detection reference signals based at least in part on the plurality of beam failure detection reference signals.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, determining the set of beam failure detection reference signals identifying a plurality of beam failure detection reference signals quasi-co-located with one or more CORESETs of one or more cells of the set of secondary cells for which uplink communication is configured and selecting the set of beam failure detection reference signals based at least in part on the plurality of beam failure detection reference signals.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, determining the set of beam failure detection reference signals using the set of secondary cell reference signal selection rules includes determining the set of beam failure detection reference signals based at least in part on at least one of a periodicity, a control resource set identifier, a secondary cell identifier, a secondary cell group identifier, a physical uplink control channel resource periodicity, or a beam failure recovery request periodicity.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, determining the set of beam failure detection reference signals includes determining the set of beam failure detection reference signals based at least in part on the set of primary cell reference signal selection rules, wherein the set of primary cell reference signal selection rules includes a rule relating to at least one of a reference signal periodicity or a control resource set identifier.

Claim 1:
A method of wireless communication performed by a user equipment, UE, comprising:
determining (<NUM>, <NUM>) a set of beam failure detection reference signals to monitor for a set of secondary cells based at least in part on a set of secondary cell reference signal selection rules, when the UE does not receive signaling identifying the set of beam failure detection reference signals;
wherein determining the set of beam failure detection reference signals based at least in part on the set of secondary cell reference signal selection rules comprises:
identifying a plurality of beam failure detection reference signals quasi-co-located with one or more control resource sets of the set of secondary cells; and
selecting the set of beam failure detection reference signals based at least in part on the plurality of beam failure detection reference signals;
monitoring (<NUM>, <NUM>) the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals; and
detecting (<NUM>, <NUM>), based at least in part on monitoring the set of beam failure detection reference signals, a beam failure for a secondary cell of the set of secondary cells.