Beam Failure Detection Reference Signal Selection for a Secondary Cell

Abstract

Aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment 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; monitor the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals; and detect a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals. Numerous other aspects are provided.

Description

[0001] Cross - Reference to Related Applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 62 / 902,735, filed on September 19, 2019, entitled "BEAM FAILURE DETECTION REFERENCE SIGNAL SELECTION FOR SECONDARY CELLS", and U.S. Non - Provisional Patent Application No. 16 / 948,237, filed on September 9, 2020, entitled "BEAM FAILURE DETECTION REFERENCE SIGNAL SELECTION FOR SECONDARY CELLS", which are hereby incorporated by reference in their entirety.

[0003] Field of Disclosure

[0004] Aspects of the present disclosure generally relate to wireless communication, and more particularly, to techniques and apparatus for beam failure detection reference signal selection for secondary cells.

[0005] Background

[0006] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ a multiple access technology capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single - Carrier Frequency Division Multiple Access (SC - FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD - SCDMA) systems, and Long Term Evolution (LTE). LTE / LTE - Advanced is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standards promulgated by the Third Generation Partnership Project (3GPP).

[0007] A wireless communication network may include a plurality of base stations (BSs) capable of supporting communications of several user equipments (UEs). The user equipment (UE) may communicate with the base station (BS) via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, the BS may be referred to as a B node, gNB, access point (AP), radio head, transmission reception point (TRP), new radio (NR) BS, 5G B node, and so on.

[0008] The above multi-access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments to communicate at the urban, national, regional, and even global levels. New radio (NR) (which may also be referred to as 5G) is an enhanced set of the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, improving services, utilizing new spectrums, and using orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) (CP-OFDM) on the downlink (DL), CP-OFDM and / or SC-FDM (e.g., also referred to as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), and supporting beamforming, multiple input multiple output (MIMO) antenna technology, and carrier aggregation to better integrate with other open standards. However, as the demand for mobile broadband access continues to grow, there is a need for further improvement in LTE and NR technologies. Preferably, these improvements should be applicable to other multi-access technologies and telecommunication standards that employ these technologies.

[0009] Summary

[0010] In some aspects, a method for a user equipment (UE) to perform wireless communication may include: determining a set of beam failure detection reference signals to be monitored 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; monitoring 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 a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals.

[0011] In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: 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; monitor the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals; and detect a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals.

[0012] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to: 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; monitor the set of beam failure detection reference signals based at least in part on determining the set of beam failure detection reference signals; and detect a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals.

[0013] In some aspects, a device for wireless communication 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; and means for detecting a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals.

[0014] Aspects generally include methods, devices, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems substantially as described herein with reference to the figures and the description and as illustrated in the figures and the description.

[0015] The foregoing has outlined rather broadly the features and technical advantages of examples in accordance with the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples may readily be used as a basis for modifying or designing other structures for carrying out the same purposes as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features of the concepts disclosed herein, in terms of both their organization and method of operation, as well as the associated advantages, will be better understood from the following description when considered in conjunction with the accompanying drawings. Each of the drawings is provided for purposes of illustration and description, and is not a definition of the limits of the claims. Brief Description of the Drawings

[0017] To understand in detail the features set forth above of the present disclosure, a more specific description of the above briefly summarized subject matter may be made with reference to the various aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only some typical aspects of the present disclosure and should not be considered to limit its scope, as the description may admit of other equally effective aspects. Like reference numerals in different drawings may identify the same or similar elements.

[0018] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication network in accordance with various aspects of the present disclosure.

[0019] Figure 2 is a block diagram conceptually illustrating an example of a base station and a UE in communication in a wireless communication network in accordance with various aspects of the present disclosure.

[0020] Figure 3 is a diagram illustrating an example of wireless communication via one or more beams in accordance with various aspects of the present disclosure.

[0021] Figure 4 is a diagram illustrating an example of a beam failure recovery procedure in accordance with various aspects of the present disclosure.

[0022] Figure 5 is a diagram illustrating an example of beam failure detection reference signal selection for a secondary cell in accordance with various aspects of the present disclosure.

[0023] Figure 6 is a diagram illustrating an example of a process, such as performed by a user equipment, in accordance with various aspects of the present disclosure.

[0024] Detailed Description

[0025] Aspects of the present disclosure are described more fully hereinafter with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, any number of the aspects set forth herein may be used to implement an apparatus or practice a method. Additionally, the scope of the present disclosure is intended to cover such apparatus or methods practiced using other structures, functionality, or a combination of structures and functionality as supplements to or in addition to the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of a claim.

[0026] Certain aspects of a telecommunications system will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in detail hereinafter and illustrated in the drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0027] It should be noted that although aspects in this document may be described using terms typically associated with 3G and / or 4G wireless technologies, aspects of the present disclosure may be applied in communication systems based on other generations, such as 5G and later generations, including NR technologies.

[0028] Figure 1 FIG. 100 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include several BSs 110 (shown as BS110a, BS110b, BS110c, and BS110d) and other network entities. A BS is an entity that communicates with user equipment (UE) and may also be referred to as a base station, NR BS, Node B, gNB, 5G Node B (NB), access point, transmission reception point (TRP), etc. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to the coverage area of a BS and / or the BS subsystem serving that coverage area, depending on the context in which the term is used.

[0029] The BS can provide communication coverage for macro cells, pico cells, femto cells, and / or another type of cell. A macro cell can cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unconstrained access by UEs with service subscriptions. A pico cell can cover a relatively small geographical area and can allow unconstrained access by UEs with service subscriptions. A femto cell can cover a relatively small geographical area (e.g., a residence) and can allow constrained access by UEs associated with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG)). The BS for a macro cell can be referred to as a macro BS. The BS for a pico cell can be referred to as a pico BS. The BS for a femto cell can be referred to as a femto BS or a home BS. In Figure 1 the example shown in, BS110a can be a macro BS for macro cell 102a, BS110b can be a pico BS for pico cell 102b, and BS110c can be a femto BS for femto cell 102c. A BS can support one or more (e.g., three) cells. The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "B node", "5G NB", and "cell" can be used interchangeably herein.

[0030] In some aspects, a cell may not have to be stationary, and the geographical area of a cell can move according to the location of a mobile BS. In some aspects, BSs can be interconnected with each other and / or interconnected to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as direct physical connections, virtual networks, and / or analogs using any suitable transport network.

[0031] The wireless network 100 can also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send the transmission of the data to a downstream station (e.g., a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. In Figure 1 the example shown in, relay station 110d can communicate with macro BS110a and UE 120d to facilitate communication between BS110a and UE 120d. A relay station can also be referred to as a relay BS, a relay base station, a relay, etc.

[0032] The wireless network 100 can be a heterogeneous network including different types of BSs (e.g., macro BS, pico BS, femto BS, relay BS, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5 to 40 watts), while pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

[0033] The network controller 130 can be coupled to a set of BSs and can provide coordination and control for these BSs. The network controller 130 can communicate with each BS via a backhaul. These BSs can also communicate with each other directly or indirectly, for example, via a wireless or wired backhaul.

[0034] UEs 120 (e.g., 120a, 120b, 120c) can be dispersed throughout the wireless network 100, and each UE can be stationary or mobile. UEs can also be referred to as access terminals, terminals, mobile stations, subscriber units, stations, etc. A UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, a superbook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium.

[0035] Some UEs can be considered machine type communication (MTC) UEs, or evolved or enhanced machine type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node can provide connectivity to a network (e.g., a wide area network such as the Internet or a cellular network) or provide connectivity to the network via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, and / or can be implemented as narrowband IoT (NB-IoT) devices. Some UEs can be considered customer premise equipment (CPE). The UE 120 can be included inside a housing that houses components of the UE 120, such as processor components, memory components, etc.

[0036] Generally, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a specific RAT and can operate on one or more frequencies. The RAT can also be referred to as radio technology, air interface, etc. The frequency can also be referred to as carrier, frequency channel, etc. Each frequency can support a single RAT in a given geographical area to avoid interference between wireless networks of different RATs. In some cases, an NR or 5G RAT network can be deployed.

[0037] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) can communicate directly using one or more sidelink channels (e.g., communicate with each other without using the base station 110 as an intermediary). For example, the UE 120 can communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which can include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, etc. In this case, the UE 120 can perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by the base station 110.

[0038] As indicated above, Figure 1 is provided as an example. Other examples may be different from the example regarding Figure 1 described.

[0039] Figure 2 shows a block diagram of a design 200 of a base station 110 and a UE 120, and the base station 110 and the UE 120 can be Figure 1 one of the base stations and one of the UEs in. The base station 110 can be equipped with T antennas 234a to 234t, and the UE 120 can be equipped with R antennas 252a to 252r, where generally T≥1 and R≥1.

[0040] At base station 110, transmit processor 220 may receive data for one or more UEs from data source 212, select one or more modulation and coding schemes (MCSs) for a UE at least in part based on channel quality indicators (CQIs) received from each UE, process (e.g., encode and modulate) the data for the UE at least in part based on the MCSs selected for each UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRSs)) and synchronization signals (e.g., primary synchronization signal (PSS) and secondary synchronization signal (SSS)). Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process its respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. In accordance with various aspects described in more detail below, position coding may be utilized to generate synchronization signals to convey additional information.

[0041] At the UE 120, antennas 252a through 252r may receive downlink signals from the base station 110 and / or other base stations and may provide the received signals to demodulators (DEMOD) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, down-convert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 256 may obtain the received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols when applicable, and provide detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide the decoded data for the UE 120 to the data sink 260, and provide the decoded control information and system information to the controller / processor 280. The channel processor may determine the reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 120 may be included in a housing.

[0042] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information from the controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by the TX MIMO processor 266 when applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, the uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the demodulator 232, detected by the MIMO detector 236 when applicable, and further processed by the receive processor 238 to obtain the decoded data and control information transmitted by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239 and provide the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0043] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2Any other component may perform one or more techniques associated with beam failure detection reference signal selection for a secondary cell, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 any other component may perform or direct operations of, for example, Figure 6 process 600 and / or other processes as described herein. The memories 242 and 282 may store data and program code for the base station 110 and the UE 120, respectively. In some aspects, the memory 242 and / or the memory 282 may include: a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, when executed by one or more processors of the base station 110 and / or the UE 120, the one or more instructions may perform or direct operations of, for example, Figure 6 process 600 and / or other processes as described herein. The scheduler 246 may schedule the UE for data transmission on the downlink and / or uplink.

[0044] In some aspects, the UE 120 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 a beam failure of a secondary cell in the set of secondary cells based at least in part on monitoring the set of beam failure detection reference signals; and so on. In some aspects, such means may include one or more components of the UE 120 described in conjunction with Figure 2 , such as the controller / processor 280, the transmit processor 264, the TX MIMO processor 266, the MOD 254, the antenna 252, the DEMOD 254, the MIMO detector 256, the receive processor 258, and so on.

[0045] As indicated above, Figure 2 is provided as an example. Other examples may be different from the example described with respect to Figure 2 .

[0046] Figure 3 is a diagram illustrating example 300 of wireless communication via one or more beams in accordance with certain aspects of the present disclosure.

[0047] As Figure 3As shown, a first device 305 (e.g., shown as a UE (such as UE 120) in example 300) may communicate with a second device 310 (e.g., shown as a BS (such as BS 110) in example 300) using one or more active beams 315. In some aspects, the first device 305 and the second device 310 may also be capable of communicating via one or more candidate beams 320. In some aspects, an active beam 315 may be selected from a set of candidate beams 320 by comparing beam parameters (e.g., RSRP, RSRQ, RSSI, etc.) of the set of candidate beams 320. For example, the active beam 315 may be the beam having the best beam parameters among all the beams in the set of candidate beams 320. In some aspects, these beams may operate in a millimeter wave radio frequency band.

[0048] In some aspects, if the active beam 315 experiences a failure, the first device 305 may perform a beam failure recovery procedure. For example, upon detecting a failure of the active beam 315, the first device 305 may attempt to communicate with the second device 310 by transmitting a beam failure recovery request (BFRQ) via one or more candidate beams 320.

[0049] The first device 305 may detect a failure at least in part based on monitoring one or more beam failure detection reference signals. For example, when the first device 305 determines that the measured RSRP of a beam failure detection reference signal meets a threshold, the first device 305 may determine that a beam failure has occurred. In some cases, the second device 310 may explicitly configure which of a plurality of possible beam failure detection reference signals the first device 305 is to monitor. For beams associated with a primary cell, when the second device 310 does not explicitly configure monitoring for the first device 305, the first device 305 may determine a beam failure detection reference signal at least in part based on a set of primary cell reference signal selection rules.

[0050] As indicated above, Figure 3 is provided as an example. Other examples may be different from the examples described with respect to Figure 3 which are described.

[0051] Figure 4 is a diagram illustrating example 400 of a beam failure recovery procedure in accordance with certain aspects of the present disclosure.

[0052] As Figure 4As shown, BS110 and UE 120 can communicate with each other using carrier aggregation. By using carrier aggregation, BS110 and UE 120 can communicate with each other using a primary cell (PCell) and one or more secondary cells (SCell). In example 400, the secondary cells are DL-only secondary cells, which means these secondary cells are configured to be used only for downlink communication and not configured for uplink communication. However, in some aspects, the secondary cells can be configured for DL and UL, UL-only, DL-only, combinations thereof, and so on.

[0053] As indicated by reference numeral 405, UE 120 can detect a beam failure on a DL-only secondary cell. For example, UE120 can detect the beam failure by monitoring a beam failure detection reference signal on the DL-only secondary cell, as described in more detail herein. As indicated by reference numeral 410, UE 120 and BS110 can use the primary cell to perform a beam failure recovery procedure. For example, UE 120 can transmit a scheduling request on the primary cell via a physical uplink control channel (PUCCH). The scheduling request can trigger a beam failure recovery (BFR), which can also be referred to as a link recovery procedure. At least partially based on receiving the scheduling request, BS110 can transmit a physical downlink shared channel (PDCCH) communication on the primary cell, and the PDCCH communication schedules PUCCH communication for the BFR.

[0054] UE 120 can receive the PDCCH communication and can transmit the scheduled PUCCH communication on the primary cell. The PUCCH communication can identify the secondary cell that has experienced the beam failure and / or can indicate a candidate beam index for a candidate beam to replace the failed beam. For example, the PUCCH communication can include a media access control (MAC) control element (CE) (MAC-CE) that identifies the failed secondary cell and the replacement beam. At least partially based on receiving the PUCCH communication, BS110 can transmit a PDCCH communication on the primary cell, and the PDCCH communication instructs UE 120 regarding the BFR procedure. For example, the PDCCH communication can instruct UE 120 to perform a random access procedure for the secondary cell on one or more candidate beams. UE 120 can perform BFR according to the PDCCH communication to obtain a new beam for communication on the secondary cell.

[0055] As indicated above, Figure 4 is provided as an example. Other examples may be different from the examples described with respect to Figure 4 the examples described above.

[0056] As described above, a UE may detect a beam failure by monitoring beam failure detection reference signals. In primary cell operation, the UE and the BS may be configured with up to 3 control resource sets (CORESETs) and up to 2 beam failure detection reference signals. However, in secondary cell operation, an additional number of CORESETs and / or beam failure detection reference signals may be possible. Additionally or alternatively, in the case where secondary cell clustering is enabled, multiple beam failure detection reference signals may share a common CORESET. As a result, the primary cell reference signal selection rules may not be applicable to the secondary cell beam failure detection reference signal selection use case.

[0057] Accordingly, some aspects described herein implement beam failure detection reference signal selection for a secondary cell. For example, a UE may determine a set of beam failure detection reference signals to monitor based at least in part on 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 implements secondary cell beam failure detection reference signal selection in situations where applying the primary cell reference signal selection rules to the secondary cell results in ambiguity. In this way, the UE increases the reliability of communication with the BS as compared to detecting a beam failure on the primary cell using only beam failure detection reference signals selected based at least in part on the primary cell reference signal selection rules.

[0058] Figure 5 is a diagram illustrating example 500 for beam failure detection reference signal selection for a secondary cell according to various aspects of the present disclosure. As Figure 5 shown, example 500 includes BS 110 and UE 120.

[0059] As Figure 5 further shown in and by reference numeral 510 in the figure, the UE 120 may determine beam failure detection reference signals to monitor. For example, the UE 120 may identify one or more beam failure detection reference signals from a set of possible beam failure detection reference signals that the UE 120 is to monitor to detect a beam failure.

[0060] In some aspects, the UE 120 may select a specific number of beam failure detection reference signals. For example, the UE 120 may determine a maximum number of beam failure detection reference signals and may select up to that maximum number. In this case, the maximum number may be at least partially based on the number of secondary cells available to the UE 120. For example, the UE 120 may be implemented to select a single beam failure detection reference signal for each secondary cell. Additionally or alternatively, the UE 120 may be implemented to select a specific number of beam failure detection reference signals for each secondary cell. Additionally or alternatively, the UE 120 may be implemented to select beam failure detection reference signals for a specific portion of the available secondary cells. In some aspects, the UE 120 may determine the maximum number of beam failure detection reference signals at least partially based on the number of secondary cell groups. In some aspects, the UE 120 may determine a maximum number for each secondary cell (e.g., up to a threshold amount of beam failure detection reference signals selected for each secondary cell), different maximum numbers for different secondary cells (e.g., a first maximum number for a first secondary cell and a second maximum number for a second secondary cell), a maximum number for each secondary cell group, etc.

[0061] In some aspects, the UE 120 may determine the maximum number at least partially based on a stored configuration, signaling received from the BS 110, etc. For example, the UE 120 may determine the maximum number at least partially based on a stored configuration and may provide a UE capability report indicating that maximum number to the BS 110 so that the BS 110 can determine the same number of beam failure detection reference signals as the UE 120 will determine. Additionally or alternatively, the BS 110 may determine the maximum number or determine a maximum number different from the maximum number determined by the UE 120 and may transmit signaling to the UE 120 to identify the maximum number determined by the BS 110 or override the maximum number determined by the UE 120.

[0062] In some aspects, the UE 120 may receive signaling from the BS 110 identifying a set of beam failure detection reference signals. For example, the BS 110 may determine a set of beam failure detection reference signals for the UE 120 to monitor and may transmit control information to identify that set of beam failure detection reference signals.

[0063] In contrast, when the UE 120 does not receive signaling identifying a set of beam failure detection reference signals from the BS 110, the UE 120 can determine the set of beam failure detection reference signals at least in part based on a set of secondary cell reference signal selection rules. For example, the UE 120 can select to monitor one or more beam failure detection reference signals that are quasi-co-located (QCL) (e.g., type D QCL) with a CORESET of the secondary cell or secondary cell group to which the UE 120 is connected. Additionally or alternatively, the UE 120 can select the beam failure detection reference signals of the secondary primary cell in the secondary cell group to which the UE 120 is connected. Additionally or alternatively, the UE 120 can select the beam failure detection reference signals of a secondary cell in the secondary cell group that is configured with a BFQR or a physical uplink control channel (PUCCH) group. Additionally or alternatively, the UE 120 can select the beam failure detection reference signals of the secondary cell (e.g., UL and DL secondary cells) in which the UE 120 is configured to communicate with the BS 110.

[0064] In some aspects, the UE 120 can resolve conflicts between multiple beam failure detection reference signals that the UE 120 can select to monitor (e.g., more than the maximum number of beam failure detection reference signals that the UE 120 can select to monitor). For example, the UE 120 can determine that the number of eligible CORESETs is greater than the maximum number of beam failure detection reference signals, and can select an eligible CORESET from which to select beam failure detection reference signals at least in part based on one or more selection criteria. In such a case, the UE 120 can use information such as the periodicity of the corresponding reference signal (e.g., of the eligible CORESET), the CORESET identifier (e.g., the value of the CORESET index), the secondary cell identifier (e.g., of the secondary cell to which the eligible CORESET applies), the secondary cell group identifier (e.g., including the secondary cell group to which the eligible CORESET applies), the PUCCH resource periodicity (e.g., for the BFRQ configured for the eligible CORESET), etc. as selection criteria. Additionally or alternatively, the UE 120 can use the primary cell reference signal selection rules as selection criteria to resolve conflicts when using the secondary cell reference signal selection rules.

[0065] As Figure 5As further shown by reference numeral 520, the UE 120 may monitor selected beam failure detection reference signals. For example, the UE 120 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 it occurs. In some aspects, the UE 120 may perform one or more measurements when monitoring the one or more beam failure detection reference signals. For example, the UE 120 may determine RSRP, RSRQ, etc. to determine whether a beam failure has occurred.

[0066] As Figure 5 As further shown by reference numeral 530, the UE 120 may detect a beam failure. For example, the UE 120 may detect a beam failure on the monitored beam failure detection reference signal on the secondary cell beam. In some aspects, the UE 120 may detect a beam failure at least in part based on a detection threshold measurement. For example, the UE 120 may determine that the RSRQ has met a threshold and may determine that a beam failure has occurred. In such a case, the UE 120 may trigger a beam failure recovery procedure, such as by transmitting a BFRQ, as described above.

[0067] As indicated above, Figure 5 is provided as an example. Other examples may be different from the examples regarding Figure 5 described.

[0068] Figure 6 is a diagram illustrating an example process 600, such as may be performed by a UE, in accordance with various aspects of the present disclosure. Example process 600 is an example where a UE (e.g., the first device 305, UE 120, etc.) performs operations associated with beam failure detection reference signal selection for a secondary cell.

[0069] As Figure 6 As shown, in some aspects, process 600 may include: determining a set of beam failure detection reference signals to be monitored for a set of secondary cells at least in part based 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 610). For example, the UE (e.g., using the controller / processor 280, etc.) may determine a set of beam failure detection reference signals to be monitored for a set of secondary cells at least in part based 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.

[0070] As Figure 6As further shown, in some aspects, process 600 may include: monitoring the beam failure detection reference signal set based at least in part on determining the beam failure detection reference signal set (block 620). For example, a UE (e.g., using antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may monitor the beam failure detection reference signal set based at least in part on determining the beam failure detection reference signal set, as described above.

[0071] As Figure 6 As further shown, in some aspects, process 600 may include: detecting a beam failure of a secondary cell in the secondary cell set based at least in part on monitoring the beam failure detection reference signal set (block 630). For example, a UE (e.g., using antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may detect a beam failure of a secondary cell in the secondary cell set based at least in part on monitoring the beam failure detection reference signal set, as described above.

[0072] Process 600 may include additional aspects, such as any individual aspect or any combination of aspects described below and / or in combination with one or more other processes described elsewhere herein.

[0073] In a first aspect, the number of beam failure detection reference signals in the beam failure detection reference signal set is defined based at least in part on a size criterion.

[0074] In a second aspect, either alone or in combination with the first aspect, one of the following: the size criterion is determined on a per-network basis, the size criterion is determined on a per-secondary cell group basis, or the size criterion is determined on a per-secondary cell basis.

[0075] In a third aspect, either alone or in combination with one or more of the first and second aspects, process 600 includes: reporting the size criterion to the base station via a UE capability message.

[0076] In a fourth aspect, either alone or in combination with one or more of the first through third aspects, process 600 includes: receiving information identifying the size criterion from the base station.

[0077] In a fifth aspect, either alone or in combination with one or more of the first through fourth aspects, process 600 includes: determining the size criterion based on a stored configuration.

[0078] In a sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the set of secondary cells is a group of secondary cells having a quasi - co - location relationship defining one or more shared beams or having a shared frequency band.

[0079] In a seventh aspect, either alone or in combination with one or more of the first to sixth aspects, determining the set of beam failure detection reference signals includes: determining that the cell configuration is configured for the UE, and using the cell configuration to determine the set of beam failure detection reference signals at least in part based on determining that the cell configuration is configured for the UE.

[0080] In an eighth aspect, either alone or in combination with one or more of the first to seventh aspects, determining the set of beam failure detection reference signals includes: determining that the cell configuration is not configured for the UE, and using a set of secondary cell reference signal selection rules to determine the set of beam failure detection reference signals at least in part based on determining that the cell configuration is not configured for the UE.

[0081] In a ninth aspect, either alone or in combination with one or more of the first to eighth aspects, using a set of secondary cell reference signal selection rules to determine the set of beam failure detection reference signals includes: identifying a plurality of beam failure detection reference signals that are quasi - co - located with one or more CORESETs of the set of secondary cells, and selecting the set of beam failure detection reference signals at least in part based on the plurality of beam failure detection reference signals.

[0082] In a tenth aspect, either alone or in combination with one or more of the first to ninth aspects, using a set of secondary cell reference signal selection rules to determine the set of beam failure detection reference signals includes: identifying a plurality of beam failure detection reference signals that are quasi - co - located with the CORESET of the secondary primary cell in the set of secondary cells, and selecting the set of beam failure detection reference signals at least in part based on the plurality of beam failure detection reference signals.

[0083] In an eleventh aspect, either alone or in combination with one or more of the first to tenth aspects, using a set of secondary cell reference signal selection rules to determine the set of beam failure detection reference signals includes: identifying a plurality of beam failure detection reference signals that are quasi - co - located with one or more CORESETs of one or more cells in the set of secondary cells that are configured with beam failure recovery requests or physical uplink control channel groups, and selecting the set of beam failure detection reference signals at least in part based on the plurality of beam failure detection reference signals.

[0084] In a twelfth aspect, either alone or in combination with one or more of the first to eleventh aspects, determining a beam failure detection reference signal set includes: identifying a plurality of beam failure detection reference signals that are quasi co-located with one or more CORESETs that identify one or more cells in a set of secondary cells for which uplink communication is configured, and selecting the beam failure detection reference signal set at least in part based on the plurality of beam failure detection reference signals.

[0085] In a thirteenth aspect, either alone or in combination with one or more of the first to twelfth aspects, using a set of secondary cell reference signal selection rules to determine a beam failure detection reference signal set includes: determining the beam failure detection reference signal set at least in part based on at least one of the following: periodicity, control resource set identifier, secondary cell identifier, secondary cell group identifier, physical uplink control channel resource periodicity, or beam failure recovery request periodicity.

[0086] In a fourteenth aspect, either alone or in combination with one or more of the first to thirteenth aspects, determining a beam failure detection reference signal set includes: determining the beam failure detection reference signal set at least in part based on a set of primary cell reference signal selection rules, where the set of primary cell reference signal selection rules includes rules related to at least one of reference signal periodicity or control resource set identifier.

[0087] Although Figure 6 example blocks of process 600 are shown, in some aspects, process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks compared to the blocks depicted in Figure 6 . Additionally or alternatively, two or more blocks of process 600 may be executed in parallel.

[0088] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be obtained by practicing the aspects.

[0089] As used herein, the term "component" is intended to be broadly construed as hardware, firmware, and / or a combination of hardware and software. As used herein, a processor is implemented with hardware, firmware, and / or a combination of hardware and software.

[0090] As used herein, depending on the context, meeting a threshold may mean that a value is greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc.

[0091] It will be apparent that the systems and / or methods described herein can be implemented in different forms of hardware, firmware, and / or a combination of hardware and software. The actual special control hardware or software code used to implement these systems and / or methods does not limit the aspects. Thus, the operations and behaviors of these systems and / or methods are described herein without reference to specific software code - understanding that software and hardware can be designed to implement these systems and / or methods at least in part based on the description herein.

[0092] Although specific feature combinations are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the aspects. In fact, many of these features can be combined in ways not specifically recited in the claims and / or not disclosed in the specification. Although each of the following dependent claims may directly depend on only one claim, the disclosure of the aspects includes each dependent claim in combination with each other claim in this set of claims. The phrase reciting "at least one of" a list of items refers to any combination of these items, including a single member. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, a - b, a - c, b - c, and a - b - c, as well as any combination having multiple identical elements (e.g., a - a, a - a - a, a - a - b, a - a - c, a - b - b, a - c - c, b - b, b - b - b, b - b - c, c - c, and c - c - c, or any other ordering of a, b, and c).

[0093] Elements, acts, or instructions used herein should not be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles "a" and "an" are intended to include one or more items and can be used interchangeably with "one or more". Additionally, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and can be used interchangeably with "one or more". Where only one item is intended, the phrase "only one" or similar language is used. Also, as used herein, the terms "having", "containing", "including", etc. are intended to be open - ended terms. Additionally, the phrase "based on" is intended to mean "at least partially based on" unless otherwise explicitly stated.

Claims

1. A method for a user equipment (UE) to perform wireless communication, comprising: When a cell configuration is not configured for the UE, using a set of sidelink cell reference signal selection rules to select a set of beam failure detection reference signals to be monitored for a set of sidelink cells, wherein the set of beam failure detection reference signals is quasi - co - located with one or more control resource sets of the set of sidelink cells; Monitoring the set of beam failure detection reference signals at least in part based on the selection of the set of beam failure detection reference signals; And Detecting a beam failure of a sidelink cell in the set of sidelink cells at least in part based on the monitoring of the set of beam failure detection reference signals.

2. The method according to claim 1, wherein The set of beam failure detection reference signals is further selected based on a maximum number of beam failure detection reference signals of the set of sidelink cells, and wherein the maximum number of beam failure detection reference signals is on a per - network basis, on a per - sidelink cell group basis, or on a per - sidelink cell basis.

3. The method according to claim 1, further comprising: Reporting the maximum number of beam failure detection reference signals of the set of sidelink cells to a network entity via a UE capability message.

4. The method according to claim 1, further comprising: Receiving, via signaling, information identifying the maximum number of beam failure detection reference signals of the set of sidelink cells.

5. The method according to claim 1, further comprising: Determining the maximum number of beam failure detection reference signals of the set of sidelink cells.

6. The method according to claim 1, wherein, The set of sidelink cells is a group of sidelink cells having a quasi - co - located relationship defining one or more shared beams or having a shared frequency band.

7. The method according to claim 1, wherein, The one or more control resource sets include the control resource set of the serving sidelink cell in the set of sidelink cells.

8. The method according to claim 1, wherein, The one or more control resource sets include the one or more control resource sets of one or more cells in the set of sidelink cells configured with a beam failure recovery request or a physical uplink control channel group.

9. The method according to claim 1, wherein, The one or more control resource sets include the one or more control resource sets of one or more cells in the set of sidelink cells for which uplink communication is configured.

10. The method according to claim 1, wherein, The set of beam failure detection reference signals is further selected at least in part based on at least one of the following: Periodicity, Control resource set identifier, Sidelink cell identifier, Sidelink cell group identifier, Physical uplink control channel resource periodicity, or Beam failure recovery request periodicity.

11. The method according to claim 1, wherein, The set of beam failure detection reference signals is further selected using a set of serving cell reference signal selection rules, and wherein the set of serving cell reference signal selection rules includes rules related to at least one of the following: Reference signal periodicity, or Control resource set identifier.

12. The method according to claim 1, wherein, The set of beam failure detection reference signals is further selected at least in part based on the capabilities of the UE.

13. The method according to claim 1, wherein, The set of beam failure detection reference signals is further selected based on the maximum number of beam failure detection reference signals.

14. The method according to claim 1, wherein The beam failure detection reference signal set is further selected using a primary cell reference signal selection rule set.

15. A user equipment (UE) for wireless communication, comprising: a memory; and one or more processors coupled to the memory, the memory and the one or more processors being configured to cause the UE to: use a secondary cell reference signal selection rule set to select beam failure detection reference signals to be monitored for a secondary cell set when the cell configuration is not configured for the UE, wherein the beam failure detection reference signal set is quasi - co - located with one or more control resource sets of the secondary cell set; monitor the beam failure detection reference signal set at least in part based on the selection of the beam failure detection reference signal set; and detect beam failures of secondary cells in the secondary cell set at least in part based on monitoring the beam failure detection reference signal set.

16. The UE according to claim 15, wherein, The beam failure detection reference signal set is further selected based on the maximum number of beam failure detection reference signals of the secondary cell set, and wherein the maximum number of beam failure detection reference signals is on a per - network basis, on a per - secondary cell group basis, or on a per - secondary cell basis.

17. The UE according to claim 15, wherein, The one or more processors are further configured to cause the UE to: report the maximum number of beam failure detection reference signals of the secondary cell set to a network entity via a UE capability message.

18. The UE according to claim 15, wherein, The one or more processors are further configured to cause the UE to: receive, via signaling, information identifying the maximum number of beam failure detection reference signals of the secondary cell set.

19. The UE according to claim 15, wherein, The one or more processors are further configured to cause the UE to: determine the maximum number of beam failure detection reference signals of the secondary cell set.

20. The UE according to claim 15, wherein, The secondary cell set is a secondary cell group having a quasi - co - located relationship defining one or more shared beams or having a shared frequency band.

21. The UE according to claim 15, wherein, The one or more control resource sets include the control resource set of the secondary primary cell in the secondary cell set.

22. The UE according to claim 15, wherein, The one or more control resource sets include the control resource sets of one or more cells in the secondary cell set configured with beam failure recovery requests or physical uplink control channel groups.

23. The UE according to claim 15, wherein, The one or more control resource sets include the control resource sets of one or more cells in the secondary cell set for which uplink communication is configured.

24. The UE according to claim 15, wherein, The beam failure detection reference signal set is further selected at least in part based on the capabilities of the UE.

25. The UE according to claim 15, wherein The beam failure detection reference signal set is further selected based on the maximum number of beam failure detection reference signals.

26. The UE according to claim 15, wherein, The beam failure detection reference signal set is further selected using a primary cell reference signal selection rule set.

27. A non - transient computer - readable medium storing an instruction set for wireless communication, the instruction set comprising: one or more instructions that, when executed by one or more processors of a user equipment (UE), cause the UE to perform the following operations: When the cell configuration is not configured for use by the UE, a set of sidelink cell reference signal selection rules is used to select beam failure detection reference signals to be monitored for a set of sidelink cells, wherein the set of beam failure detection reference signals is quasi - co - located with one or more control resource sets of the set of sidelink cells; monitoring the set of beam failure detection reference signals is at least partially based on selecting the set of beam failure detection reference signals; and detecting beam failures of sidelink cells in the set of sidelink cells is at least partially based on monitoring the set of beam failure detection reference signals.

28. The non-transitory computer-readable medium according to claim 27, wherein, The set of beam failure detection reference signals is further selected based on the maximum number of beam failure detection reference signals of the set of sidelink cells.

29. The non-transitory computer-readable medium according to claim 27, wherein, The set of beam failure detection reference signals is further selected using a set of primary cell reference signal selection rules.

30. An apparatus for wireless communication, comprising: means for using a set of sidelink cell reference signal selection rules to select beam failure detection reference signals to be monitored for a set of sidelink cells when the cell configuration is not configured for use by the apparatus, wherein the set of beam failure detection reference signals is quasi - co - located with one or more control resource sets of the set of sidelink cells; means for monitoring the set of beam failure detection reference signals at least partially based on selecting the set of beam failure detection reference signals; and means for detecting beam failures of sidelink cells in the set of sidelink cells at least partially based on monitoring the set of beam failure detection reference signals.

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