High reliability transmission mode for two-step secondary cell beam failure recovery procedure

Abstract

Aspects of the present disclosure relate to wireless communications and, more particularly, to techniques for performing beam failure recovery involving a secondary cell.

Description

[0001] Priority claim

[0002] This application claims priority to U.S. Application No. 17 / 067,318, filed on October 9, 2020, which claims priority to and the benefit of U.S. Provisional Application No. 62 / 914,365, filed on October 11, 2019, both of which are expressly incorporated herein by reference as if fully set forth below and for all applicable purposes.

[0003] background

[0004] Public domain

[0005] Aspects of the present disclosure relate to wireless communications and, more particularly, to techniques for performing beam failure recovery involving a secondary cell.

[0006] Related technical description

[0007] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems include Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, 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, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, to name just a few.

[0008] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is an enhancement set of the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0009] However, as the demand for mobile broadband access continues to grow, there is a need for further improvements to NR and LTE technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

[0010] Overview

[0011] The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the disclosure as expressed in the appended claims, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "Detailed Description," it will be understood how the features of the present disclosure provide advantages including improved reliability of beam recovery message delivery.

[0012] Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE). The method generally includes performing beam failure detection (BFD) on a beam pair link (BPL) associated with a secondary cell (SCell) in carrier aggregation (CA); sending a beam failure recovery request (BFRQ) message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receiving a message from the other cell, and sending a media access control (MAC) control element (CE) after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0013] Certain aspects of the present disclosure relate to an apparatus for wireless communication by a UE. The apparatus generally includes a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: perform beam BFD for a BPL associated with an SCell in CA; send a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receive a message from the other cell; and send a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0014] Certain aspects of the present disclosure relate to an apparatus for wireless communication by a UE. The apparatus generally includes: a device for performing beam BFD for a BPL associated with an SCell in CA; a device for sending a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; a device for receiving a message from the other cell; and a device for sending a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0015] Certain aspects of the present disclosure relate to a computer-readable medium having instructions stored thereon for: performing beam BFD for a BPL associated with an SCell in a CA; sending a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receiving a message from the other cell; and sending a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0016] Certain aspects of the present disclosure provide a method for wireless communication by a network entity. The method generally includes: receiving a BFRQ message from a UE, the BFRQ message indicating a beam failure detected in an SCell and including an indication of a candidate recovery beam for the SCell; sending a message to the UE; and receiving a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0017] Certain aspects of the present disclosure relate to an apparatus for wireless communication by a UE. The apparatus generally includes a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: receive a BFRQ message from the UE, the BFRQ message indicating a beam failure detected in an SCell and including an indication of a candidate recovery beam for the SCell; send a message to the UE; and receive a media access control MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0018] Certain aspects of the present disclosure relate to an apparatus for wireless communication by a UE. The apparatus generally includes: a device for receiving a BFRQ message from the UE, the BFRQ message indicating a beam failure detected in an SCell and including an indication of a candidate recovery beam for the SCell; a device for sending a message to the UE; and a device for receiving a media access control MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0019] Certain aspects of the present disclosure relate to a computer-readable medium having instructions stored thereon for: receiving a BFRQ message from a UE, the BFRQ message indicating a beam failure detected in an SCell and including an indication of candidate recovery beams for the SCell; sending a message to the UE; and receiving a media access control MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0020] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are only indicative of several of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to understand in detail the manner in which the above-stated features of the present disclosure are used, a more particular description of the content briefly summarized above may be made with reference to various aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only certain typical aspects of the present disclosure and are not to be considered limiting of its scope, as the description may admit to other equally effective aspects.

[0023] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0024] Figure 2 is a block diagram conceptually illustrating designs of example base stations (BSs) and user equipment (UEs) in accordance with certain aspects of the present disclosure.

[0025] Figure 3

[0026] are example beam failure detection and recovery procedures that may be enhanced in accordance with certain aspects of the present disclosure.

[0026] Figure 4

[0013] Example operations for wireless communications by a UE are illustrated in accordance with certain aspects of the present disclosure.

[0027] Figure 5

[0013] Example operations for wireless communications by a network entity are illustrated in accordance with certain aspects of the present disclosure.

[0028] Figure 6 are example beam failure detection and recovery procedures in accordance with certain aspects of the present disclosure.

[0029] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation.

[0030] Detailed Description

[0031] Various aspects of the present disclosure relate to wireless communications, and more particularly to techniques for performing beam failure recovery involving secondary cells. In some cases, one or more mechanisms may be utilized to improve the reliability of the BFR mechanism, thereby implicitly providing a higher priority for recovery message delivery. Examples of such mechanisms include beam sweeping and repetition.

[0032] The following description provides examples of various aspects of the present disclosure, without limiting the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, replace, or add various procedures or components. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted, or combined. Moreover, the features described with reference to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionalities, or structures and functionalities as supplements to the various aspects of the present disclosure set forth herein or in addition. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of the claims. The wording "exemplary" is used herein to mean "used as an example, instance, or explanation". Any aspect described as "exemplary" herein is not necessarily to be interpreted as being superior to or superior to other aspects.

[0033] In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific radio access technology (RAT) and may operate on one or more frequencies. RAT may also be referred to as a radio technology, air interface, etc. Frequency may also be referred to as a carrier, subcarrier, frequency channel, frequency tone, subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

[0034] The techniques described herein can be used for various wireless networks and radio technologies. For clarity, although various aspects may be described herein using terms commonly associated with 3G, 4G and / or new radio (e.g., 5G NR) wireless technologies, various aspects of the present disclosure may be applied in communication systems based on other generations.

[0035] NR access can support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or more), millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or more), massive machine type communication MTC (mMTC) targeting non-backward compatible MTC technology, and / or mission critical services targeting ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet corresponding quality of service (QoS) requirements. In addition, these services can coexist in the same subframe.

[0036] Some wireless networks utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also often referred to as frequency tones, frequency bins, etc. Each subcarrier can be modulated with data. In general, modulation symbols are sent in the frequency domain for OFDM and in the time domain for SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. The system bandwidth can also be divided into subbands.

[0037] 5G NR can utilize OFDM with a cyclic prefix (CP) on the uplink and downlink, and includes support for half-duplex operation using time division duplex (TDD). A subframe can be 1ms, but the basic transmission time interval (TTI) can be called a time slot. A subframe contains a variable number of time slots (e.g., 1, 2, 4, 8, 16...time slots), depending on the subcarrier spacing (SCS). NR resource blocks (RBs) can be 12 consecutive frequency subcarriers. NR can support a base SCS of 15KHz, and other subcarrier spacings can be defined relative to the base SCS, such as 30kHz, 60kHz, 120kHz, 240kHz, etc. The symbol and time slot lengths scale with the SCS. The CP length also depends on the SCS. 5G NR can also support beamforming and can dynamically configure the beam direction. Multiple-input multiple-output (MIMO) transmission with precoding can also be supported. In some examples, MIMO configurations in the DL can support up to 8 transmit antennas (with multi-layer DL transmissions of up to 8 streams) and up to 2 streams per UE. In some examples, multi-layer transmissions of up to 2 streams per UE can be supported. Aggregation of multiple cells can be supported using up to 8 serving cells.

[0038] Figure 1 An example wireless communication network 100 is illustrated in which aspects of the present disclosure may be performed. A UE 120 of the network 100 may have a UE configured to perform Figure 4 The beam failure recovery module 122 of operation 400 and / or the BS 110 of the network 100 may have a module configured to perform Figure 5 The beam failure recovery module 112 of operation 500 is used.

[0039] like Figure 1As illustrated in , the wireless communication network 100 may include several base stations (BSs) 110a-z (each also individually referred to herein as BS 110 or collectively referred to as BS 110) and other network entities. BS 110 may provide communication coverage for a particular geographic area (sometimes referred to as a "cell"), which may be stationary or mobile depending on the location of mobile BS 110. In some examples, BS 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) in the wireless communication network 100 via various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network. Figure 1 In the example shown in , BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for a pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. The BS may support one or more cells. BS 110 communicates with user equipment (UE) 120a-y (each also individually referred to herein as UE 120 or collectively referred to as UE 120) in the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile.

[0040] The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.), which receives transmissions of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and sends transmissions of data and / or other information to a downstream station (e.g., UE 120 or BS 110), or the relay station relays transmissions between UEs 120 to facilitate communication between the devices.

[0041] A network controller 130 may couple to a set of BSs 110 and provide coordination and control for the BSs 110. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other (eg, directly or indirectly) via a wireless or wired backhaul.

[0042] Figure 2 1 and 120a (eg, in the example embodiment of the present invention) that can be used to implement various aspects of the present disclosure. Figure 1 Example components of the wireless communication network 100).

[0043] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for the exchange of control commands between wireless nodes. For example, a base station may transmit a MAC CE to a user equipment (UE) to place the UE in a discontinuous reception (DRX) mode to reduce the power consumption of the UE. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel. The MAC-CE may also be used to convey information that facilitates communication, such as information about buffer status and available power headroom.

[0044] The processor 220 may process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols (such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a reference signal (CRS) that varies from cell to cell). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols, where applicable, and may provide an output symbol stream to a modulator (MOD) 232a-232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signals from the modulators 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0045] At UE 120a, antennas 252a-252r may receive downlink signals from BS 110a and may provide received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all demodulators 254a-254r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to a data sink 260, and provide decoded control information to a controller / processor 280.

[0046] On the uplink, at the UE 120a, the transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for a reference signal (e.g., a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by a demodulator in a transceiver 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signal from the UE 120a may be received by the antenna 234, processed by the modulator 232, detected by the MIMO detector 236, if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120a. Receive processor 238 may provide decoded data to data sink 239 and decoded control information to controller / processor 240 .

[0047] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0048] The controller / processor 280 and / or other processors and modules at the UE 120a may perform or direct the execution of processes for the techniques described herein. Figure 2 As shown in FIG. 1 , the controller / processor 240 of BS 110a has a configuration that can be configured to perform Figure 5 The beam failure recovery module 241 of operation 500 is as follows. Figure 2As shown in FIG. 1 , according to various aspects described herein, the controller / processor 280 of the UE 120a has a plurality of processors configured to perform Figure 4 The beam failure recovery module 281 of operation 400. Although shown as being at the controller / processor, other components of the UE 120a and BS 110a may also be used to perform the operations described herein.

[0049] Some systems (such as NR) support carrier aggregation (CA). With CA, a UE can use multiple carriers / cells to communicate with a BS (or multiple BSs). CA involves a primary cell (PCell) and at least one secondary cell (SCell). The SCell can be configured for downlink only, or can be configured for both uplink and downlink. PCell and SCell can be in different frequency bands, such as a PCell in one frequency range (e.g., FR1, sub-6GHz) and a SCell in another frequency range (FR2, 28GHz). PCell and SCell can use different frequency modulation intervals or subcarrier spacings (SCS), resulting in different symbol lengths for PCell and SCell. For example, the symbol length for 120KHz SCS in F1 is eight times shorter than the symbol length for 15KHz SCS in FR1.

[0050] In FR2 (mmW (millimeter wave) communication), directional beamforming is used between the UE and the gNB. As such, the UE and the gNB communicate via a beam pair link (BPL). In some cases, the UE may detect a beam failure (e.g., the RSRP of the BPL is bad) and send a beam failure recovery request (BFRQ) to the gNB. This BFR procedure may be cell-specific (e.g., there may be PCell BFR and SCell BFR).

[0051] As mentioned above, aspects of the present disclosure relate to beam failure detection and recovery. In some systems, narrow beam transmission and reception help improve link budget at millimeter wave (mmW) frequencies, but may be prone to beam failure. In mmW, directional beamforming is used between the UE and the BS, and the UE and the BS communicate via a beam pair link (BPL). Beam failure generally refers to a scenario where the beam quality drops below a threshold, which can lead to a radio link failure (RLF). NR supports lower layer signaling for recovering from beam failures, which is called beam recovery. For example, instead of initiating a cell reselection when the beam quality becomes too low, a beam pair reselection within a cell can be performed.

[0052] Figure 3An example beam failure detection and recovery procedure according to certain aspects of the present disclosure is illustrated. A beam failure may be detected by monitoring a beam failure detection (BFD) reference signal (RS) and evaluating whether a beam failure trigger condition has been met. Figure 3 As shown in , UE 302 monitors the BFD RS from SCell 304 at 308. In some examples, beam failure detection is triggered if the estimated block error rate (BLER) of the reference signal associated with the configured control resource set (CORESET) is above a threshold (e.g., 10%). In some examples, UE 302 detects beam failure when the reference signal received power (RSRP) of the BPL is below a threshold.

[0053] To recover SCell 304, UE 302 may send a beam failure request (BFRQ) message on another cell. Figure 3 As shown in FIG, a BFRQ is sent on PCell 306. In NR systems, a two-step BFRQ may be used. The BFRQ may request a new transmission. Figure 3 As shown in FIG. 3 , after detecting a beam failure, UE 302 sends a first step (or first phase) of a BFRQ at 310. The first step of a BFRQ message may include a scheduling request (SR) on PCell 306. The SR may be sent on a dedicated SR resource. The SR may request scheduling for a second step (or second phase) of the BFRQ message. Figure 3 As shown in , at 312, UE 302 may receive a PDCCH in response to the SR from PCell 306, thereby scheduling a second step of the BFRQ message. Then, UE 302 may subsequently send the scheduled second step of the BFRQ message on PCell 306 at 314. For example, Figure 3 As shown in , UE 302 sends a PUSCH including a MAC CE. The MAC CE may include an index of a failed CC and a new recovery beam candidate beam. In some examples, to find a candidate new beam, the UE may monitor a beam identification reference signal.

[0054] In 316, Figure 3 As shown in , PCell 306 responds to the BFRQ by transmitting a beam failure recovery response (BFRR) message to UE 302. The BFRR message can acknowledge the MAC CE and include an uplink grant that schedules a new transmission. For example, the uplink grant can schedule a transmission for the same HARQ process as the PUSCH that carries the MAC CE in step two of the BFRQ. In some examples, the BFRR is sent on a CORESET that UE 302 monitors for the response (e.g., referred to as CORESET-BFR).

[0055] If the response is successfully received, the beam recovery is complete and a new BPL can be established. If the UE 302 cannot detect any response within a certain period of time, the UE 302 can perform a retransmission of the request. If the UE 302 cannot detect any response after a specified number of retransmissions, the UE 302 can notify higher layers, potentially causing RLF and cell reselection.

[0056] After receiving the BFRR at 316 and before establishing a new BPL, the UE 302 may communicate on the SCell 304 using the default beam.

[0057] Techniques and apparatus for a UE and a BS (associated with a SCell) to determine when to apply a default beam are desired.

[0058] Example of high reliability transmission (Tx) mode for two-step SCell BFR

[0059] Aspects of the present disclosure relate to wireless communications, and more particularly to techniques for performing beam failure recovery involving secondary cells. In some cases, one or more mechanisms may be utilized to improve the reliability of beam failure recovery (BFR) mechanisms by implicitly providing a higher priority for recovery messaging. Examples of such mechanisms include beam sweeping and repetition.

[0060] As mentioned above, for secondary cell (SCell) beam failure detection, for example, according to the above reference Figure 3 A two-step BFRQ procedure is described, where a BFR request (BFRQ) may be sent in a primary cell (PCell) physical uplink control channel (PUCCH) as a dedicated scheduling request. Techniques described herein utilize one or more mechanisms to improve the reliability of the BFR mechanism, such as implicitly providing a higher priority for recovery messaging (e.g., a media access control (MAC) control element (CE) sent to a user equipment (UE) (e.g., which may include information about the cell in which a beam failure was detected and / or an indication of a new candidate beam)).

[0061] Figure 4 4 is a flow diagram illustrating example operations 400 for wireless communication in accordance with certain aspects of the present disclosure. Operations 400 may be performed, for example, by a UE (such as, for example, UE 120a in wireless communication network 100). Operations 400 may be implemented as a processor (e.g., Figure 2 Further, in operation 500, the transmission and reception of signals by the UE may be performed, for example, by one or more antennas (e.g., Figure 2In some aspects, the transmission and / or reception of signals by the UE may be achieved by obtaining and / or outputting signals via a bus interface of one or more processors (eg, controller / processor 280).

[0062] Operations 400 may begin at 402 by performing beam failure detection (BFD) on a beam pair link (BPL) associated with an SCell in carrier aggregation (CA). At 404, the UE sends a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell. At 406, the UE receives a message from the other cell. At 408, the UE sends a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0063] Figure 5 5 is a flow diagram illustrating example operations 500 for wireless communication in accordance with certain aspects of the present disclosure. Operations 500 may be performed, for example, by a BS (such as, for example, BS 110a in wireless communication network 100). Operations 500 may be operations performed by the BS that are complementary to operations 400 performed by a UE. Operations 500 may be implemented as a process on one or more processors (e.g., Figure 2 Further, signal transmission and reception by the BS in operation 500 may be performed by, for example, one or more antennas (e.g., Figure 2 In some aspects, signal transmission and / or reception by the BS may be achieved by obtaining and / or outputting signals via a bus interface of one or more processors (eg, controller / processor 240).

[0064] Operations 500 may begin at 502 by receiving a BFRQ message from a UE indicating a beam failure detected in an SCell and including an indication of a candidate recovery beam for the SCell. At 504, the network entity sends the message to the UE. At 506, the network entity receives a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0065] You can refer to Figure 6 Call flow diagram to understand Figure 4 and Figure 5 Operations 400 and 500. As illustrated, after detecting beam failure, the UE sends a BFRQ (eg, a scheduling request in a PCell or a PUCCH-BFR).

[0066] like Figure 6As explained in , in some cases, the response (e.g., a message from PCELL) after the UE transmits the PUCCH-BFR can be a normal uplink grant (e.g., with a cellular cell radio network temporary identifier (C-RNTI) and / or modulation and coding scheme (MCS) C-RNTI).

[0067] After receiving the response message from the PCell, the UE may transmit a MAC CE (eg, with information about the cell in which the failure was detected and the candidate beams) using a high reliability transmission (Tx) mode.

[0068] By transmitting the SCell BFR MAC CE with higher reliability (eg, employing beam sweeping and / or repetition), the SCell BFR MAC CE may actually have a higher priority.

[0069] As illustrated, in some cases, a BFR MAC CE may be transmitted within a time window starting from the end of the PCell response (e.g., with beam sweeping and / or repetition). Within the time window, the UE may transmit a MAC CE (e.g., in step 2 of a two-step process) using a previously known UL grant based on downlink control information (DCI) (e.g., via a PCell response) or based on a configured grant (CG), which generally refers to a grant for periodic uplink resources.

[0070] In some cases, the UE may overwrite the relevant uplink grant information used to transmit the MAC CE, for example, based on a preconfigured high reliability Tx mode.

[0071] In some cases, the high reliability Tx mode may be based on a predetermined beam sweeping pattern (e.g., the UE transmits the MAC CE multiple times using different transmit beams according to the pattern). In some cases, the high reliability Tx mode may be a predetermined repetitive pattern (e.g., using the indicated beam given by the original uplink grant). The beam sweeping mode and / or repetitive mode may be configured (e.g., signaled via radio resource control (RRC), MAC CE, or DCI).

[0072] The duration of the time window duration (e.g., from the triggering / start of the PCell response) can be a fixed value, e.g., in number of time slots (e.g., ceil(N2 / 14)). In some cases, the duration of the time window can be dynamically configured by the gNB.

[0073] Example Embodiments

[0074] Embodiment 1: A method for wireless communication by a user equipment (UE), comprising: performing beam failure detection (BFD) on a beam pair link (BPL) associated with a secondary cell (SCell) in carrier aggregation (CA); sending a beam failure recovery request (BFRQ) message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receiving a message from the other cell; and sending a media access control (MAC) control element (CE) after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0075] Embodiment 2: The method as described in Embodiment 1, wherein the message conveys the grant of resources for sending the MAC-CE.

[0076] Embodiment 3: A method as described in Embodiment 1, wherein the one or more mechanisms include beam sweeping, in which different transmit beams are used to send the MAC CE multiple times.

[0077] Embodiment 4: A method as described in Embodiment 3, wherein the different transmit beams are defined by a beam sweep pattern.

[0078] Embodiment 5: The method as described in Embodiment 4 further includes receiving a signal indicating the beam sweeping mode.

[0079] Embodiment 6: The method as described in any one of Embodiments 3 to 5, wherein the beam sweeping is performed within a time window triggered by reception of the message from the other cell.

[0080] Embodiment 7: The method as described in Embodiment 6, wherein the time window is dynamically configured.

[0081] Embodiment 8: The method as described in any one of Embodiments 1 to 7, wherein the one or more mechanisms include sending the MAC CE by repetition.

[0082] Embodiment 9: A method as described in Embodiment 8, wherein the repetition is defined by a repetition pattern and is sent according to a beam indicated in the message.

[0083] Embodiment 10: The method as described in Embodiment 9 further includes receiving signaling indicating the repetition mode.

[0084] Embodiment 11: The method of embodiment 10, wherein the repetition is performed within a time window triggered by reception of the message from the other cell.

[0085] Embodiment 12: A method as described in Embodiment 11, wherein the time window is dynamically configured.

[0086] Embodiment 13: The method as described in any one of Embodiments 1 to 12, wherein the message from the other cellular cell includes an uplink grant scrambled by C-RNTI or MCS-C-RNTI.

[0087] Embodiment 14: A method for wireless communication by a network entity, comprising: receiving a BFRQ message from a UE, the BFRQ message indicating a beam failure detected in a SCell and including an indication of a candidate recovery beam for the SCell; sending a message to the UE; and receiving a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0088] Embodiment 15: The method of embodiment 14, wherein the message conveys a grant of resources for sending the MAC-CE.

[0089] Embodiment 16: A method as described in Embodiment 14 or 15, wherein the one or more mechanisms include beam sweeping, in which the UE uses different transmit beams to send the MAC CE multiple times.

[0090] Embodiment 17: A method as described in Embodiment 16, wherein the different transmit beams are defined by a beam sweep pattern.

[0091] Embodiment 18: The method as described in Embodiment 17 further includes providing signaling indicating the beam sweeping mode to the UE.

[0092] Embodiment 19: A method as described in any one of Embodiments 16 to 18, wherein the beam sweeping is performed within a time window triggered by the reception of the message.

[0093] Embodiment 20: A method as described in Embodiment 19, wherein the time window is dynamically configured by the network entity.

[0094] Embodiment 21: A method as described in any one of Embodiments 14 to 20, wherein the one or more mechanisms include sending the MAC CE by repetition.

[0095] Embodiment 22: A method as described in Embodiment 21, wherein the repetition is defined by a repetition pattern and is sent according to a beam indicated in the message.

[0096] Embodiment 23: The method as described in Embodiment 22 further includes providing signaling indicating the repetition mode to the UE.

[0097] Embodiment 24: A method as described in Embodiment 23, wherein the repetition is performed within a time window triggered by the reception of the message.

[0098] Embodiment 25: A method as described in Embodiment 24, wherein the time window is dynamically configured by the network entity.

[0099] Embodiment 26: A method as described in any one of Embodiments 14 to 25, wherein the message includes an uplink grant scrambled by C-RNTI or MCS-C-RNTI.

[0100] Embodiment 27: An apparatus for wireless communication by a UE, comprising a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: perform BFD on a BPL associated with an SCell in a CA; send a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receive a message from the other cell; and send a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0101] Embodiment 28: The apparatus of Embodiment 27, wherein the message conveys a grant of resources for sending the MAC-CE.

[0102] Embodiment 29: An apparatus for wireless communication by a UE, comprising a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: receive a BFRQ message from the UE, the BFRQ message indicating a beam failure detected in an SCell and including an indication of a candidate recovery beam for the SCell; send a message to the UE; and receive a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0103] Embodiment 30: The apparatus of Embodiment 29, wherein the message conveys a grant of resources for sending the MAC-CE.

[0104] Embodiment 31: A device for wireless communication by a UE, comprising: a device for performing beam BFD for a BPL associated with an SCell in a CA; a device for sending a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; a device for receiving a message from the other cell; and a device for sending a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0105] Embodiment 32: A computer-readable medium having stored thereon instructions for: performing beam BFD for a BPL associated with an SCell in a CA; sending a BFRQ message to another cell, the BFRQ message including an indication of a candidate recovery beam for the SCell; receiving a message from the other cell; and sending a MAC CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0106] Embodiment 33: A device for wireless communication by a UE, comprising: a device for receiving a BFRQ message from the UE, the BFRQ message indicating a beam failure detected in a SCell and including an indication of a candidate recovery beam for the SCell; a device for sending a message to the UE; and a device for receiving a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0107] Embodiment 34: A computer-readable medium having stored thereon instructions for: receiving a BFRQ message from a UE, the BFRQ message indicating a beam failure detected in a SCell and including an indication of a candidate recovery beam for the SCell; sending a message to the UE; and receiving a MAC CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability.

[0108] The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology under development.

[0109] In 3GPP, the term "cell" may refer to the coverage area of ​​a B node (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and BS, next-generation B node (gNB or g B node), access point (AP), distributed unit (DU), carrier, or transmission reception point (TRP) may be used interchangeably. The BS may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a radius of several thousand meters) and may allow unrestricted access by UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a residence, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS.

[0110] UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smart phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, ultrabook, appliance, medical device or medical equipment, biometric sensor / device, wearable device (such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music device, video device, satellite radio, etc.), transportation component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via wireless or wired medium. Some UEs may be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can provide connectivity for or to a network (e.g., a wide area network (such as the Internet) or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0111] In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., BS) allocates resources for communication between some or all devices and equipment within its service area or cell. A scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. A base station is not the only entity that can be used as a scheduling entity. In some examples, a UE may act as a scheduling entity, and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs may utilize resources scheduled by the UE for wireless communication. In some examples, a UE may act as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In a mesh network example, UEs may communicate directly with each other in addition to communicating with a scheduling entity.

[0112] In some examples, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh networks, and / or various other suitable applications. Generally, a sidelink signal may refer to a signal that is communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, the sidelink signal may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum).

[0113] Each method disclosed herein includes one or more steps or actions for implementing the method. These method steps and / or actions can be interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be changed without departing from the scope of the claims.

[0114] As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0115] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0116] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be easily understood by those skilled in the art, and the universal principles defined herein can be applied to other aspects. Thus, the claims are not intended to be limited to the various aspects shown herein, but should be granted the full scope consistent with the language of the claims, wherein the singular reference to the element is not intended to mean "there is and only one" (unless specifically stated) but "one or more". Unless otherwise specifically stated, the term "some / some" refers to one or more. The elements of the various aspects described throughout this disclosure are all structural and functional equivalents currently or hereafter known to ordinary technicians in the art and are expressly incorporated herein by reference, and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be donated to the public, regardless of whether such disclosure is explicitly recorded in the claims. Any element of the claim should not be interpreted under the provisions of 35 USC§112(f), unless the element is explicitly stated using the phrase "device for..." or in the case of a method claim, the element is stated using the phrase "step for..."

[0117] The various operations of the methods described above may be performed by any suitable device capable of performing the corresponding functions. These devices may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations illustrated in the accompanying drawings, these operations may have corresponding paired device-plus-function components with similar numbers.

[0118] The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0119] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the user terminal 120 (see Figure 1 ), a user interface (e.g., a keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and will not be described further. The processor may be implemented with one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuit systems capable of executing software. Those skilled in the art will recognize how to best implement the functionality described with respect to the processing system, depending on the specific application and the overall design constraints imposed on the overall system.

[0120] If implemented in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or other. Computer-readable media include both computer storage media and communication media, which include any media that facilitate the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. As an example, a machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium having instructions stored thereon that is separated from a wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or additionally, a machine-readable medium or any part thereof may be integrated into a processor, such as a cache and / or a general register file, which may be the case. As an example, examples of machine-readable storage media may include RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. Machine-readable media may be implemented in a computer program product.

[0121] A software module may include a single instruction, or many instructions, and may be distributed over several different code segments, distributed between different programs, and distributed across multiple storage media. A computer-readable medium may include several software modules. These software modules include instructions that cause a processing system to perform various functions when executed by an apparatus such as a processor. These software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or may be distributed across multiple storage devices. As an example, when a triggering event occurs, a software module may be loaded into a RAM from a hard drive. During the execution of a software module, a processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When describing the functionality of a software module as described below, it will be understood that such functionality is implemented by the processor when the processor executes instructions from the software module.

[0122] Likewise, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared (IR), radio, and microwave), then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Disks, where disks often reproduce data magnetically, and discs reproduce data optically with lasers. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of computer-readable media.

[0123] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having stored (and / or encoded) thereon instructions that can be executed by one or more processors to perform the operations described herein, such as for performing the operations described herein and in Figure 4 and / or Figure 5 Instructions for the operations explained in .

[0124] In addition, it should be appreciated that modules and / or other appropriate means for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.) so that once the storage device is coupled to or provided to a user terminal and / or base station, the device can obtain the various methods. In addition, any other suitable technology suitable for providing the methods and techniques described herein to a device may be utilized.

[0125] It will be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment UE, comprising: performing beam failure detection BFD on a beam pair link BPL associated with a secondary cell SCell in carrier aggregation CA; Sending a failure recovery request (BFRQ) message to another cell, wherein the BFRQ message includes an indication of a candidate recovery beam for the SCell; receiving a message from the another cell; as well as sending a media access control MAC control element CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability, wherein the one or more mechanisms include: beam sweeping and using different transmit beams to send the MAC CE multiple times, or The MAC CE is sent with a repetition defined by a repetition pattern.

2. The method of claim 1, wherein: The message conveys a grant of resources for sending the MAC CE.

3. The method of claim 1, wherein: The different transmit beams are defined by beam sweep patterns. The method of claim 3 , further comprising receiving signaling indicating the beam sweeping pattern.

5. The method of claim 1, wherein: The beam sweeping is performed within a time window triggered by reception of the message from the another cell.

6. The method of claim 5, wherein: The time window is dynamically configured.

7. The method of claim 1, wherein: The repetitions are sent according to the beam indicated in the message.

8. The method of claim 7, further comprising receiving signaling indicating the repetition pattern.

9. The method of claim 8, wherein: The repetition is performed within a time window triggered by reception of the message from the another cell.

10. The method of claim 9, wherein: The time window is dynamically configured.

11. The method of claim 1, wherein: The message from the other cell includes an uplink grant scrambled by a C-RNTI or an MCS-C-RNTI.

12. A method for wireless communication by a network entity, comprising: receiving a beam failure recovery request (BFRQ) message from a user equipment (UE), the BFRQ message indicating a beam failure detected in a secondary cell (SCell) and including an indication of a candidate recovery beam for the SCell; Sending a message to the UE; as well as receiving a media access control MAC control element CE after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability, wherein the one or more mechanisms include: beam sweeping and sending the MAC CE multiple times using different transmit beams, or The MAC CE is sent with a repetition defined by a repetition pattern.

13. The method of claim 12, wherein: The message conveys a grant of resources for sending the MAC CE.

14. The method of claim 12, wherein: The different transmit beams are defined by beam sweep patterns.

15. The method of claim 14, further comprising providing signaling to the UE indicating the beam sweeping pattern.

16. The method of claim 12, wherein: The beam sweeping is performed within a time window triggered by reception of the message.

17. The method of claim 16, wherein: The time window is dynamically configured by the network entity.

18. The method of claim 12, wherein: The repetitions are sent according to the beam indicated in the message.

19. The method of claim 18, further comprising providing signaling to the UE indicating the repetition pattern.

20. The method of claim 19, wherein: The repetition is performed within a time window triggered by the receipt of the message.

21. The method of claim 20, wherein: The time window is dynamically configured by the network entity.

22. The method of claim 12, wherein: The message includes an uplink grant scrambled by C-RNTI or MCS-C-RNTI.

23. An apparatus for wireless communication by a user equipment UE, comprising: a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: performing beam failure detection BFD on a beam pair link BPL associated with a secondary cell SCell in carrier aggregation CA; Sending a failure recovery request (BFRQ) message to another cell, wherein the BFRQ message includes an indication of a candidate recovery beam for the SCell; receiving a message from the another cell; as well as Sending a media access control MAC control element CE after receiving the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability, wherein the one or more mechanisms include: beam sweeping and using different transmit beams to send the MAC CE multiple times, or The MAC CE is sent with a repetition defined by a repetition pattern.

24. The device of claim 23, wherein: The message conveys a grant of resources for sending the MAC CE.

25. The apparatus of claim 23, wherein: The different transmit beams are defined by beam sweep patterns.

26. The apparatus of claim 25, the memory and the at least one processor further configured to receive signaling indicative of the beam sweeping pattern.

27. The apparatus of claim 23, wherein: The beam sweeping is performed within a time window triggered by reception of the message from the another cell.

28. The apparatus of claim 27, wherein: The time window is dynamically configured.

29. The apparatus of claim 23, wherein: The repetitions are sent according to the beam indicated in the message.

30. The apparatus of claim 29, the memory and the at least one processor further configured to receive signaling indicating the repetitive pattern.

31. The device of claim 30, wherein: The repetition is performed within a time window triggered by reception of the message from the another cell.

32. The apparatus of claim 31, wherein: The time window is dynamically configured.

33. The apparatus of claim 23, wherein: The message from the other cell includes an uplink grant scrambled by a C-RNTI or an MCS-C-RNTI.

34. An apparatus for wireless communication by a network entity, comprising: a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: receiving a beam failure recovery request (BFRQ) message from a user equipment (UE), the BFRQ message indicating a beam failure detected in a secondary cell (SCell) and including an indication of a candidate recovery beam for the SCell; Sending a message to the UE; as well as A media access control MAC control element CE is received after sending the message, wherein the MAC CE is sent using one or more mechanisms to enhance reliability, wherein the one or more mechanisms include: beam sweeping and using different transmit beams to send the MAC CE multiple times, or The MAC CE is sent with a repetition defined by a repetition pattern.

35. The apparatus of claim 34, wherein: The message conveys a grant of resources for sending the MAC CE.

36. The apparatus of claim 34, wherein: The different transmit beams are defined by beam sweep patterns.

37. The apparatus of claim 36, the memory and the at least one processor being further configured to provide signaling indicating the beam sweeping pattern to the UE.

38. The apparatus of claim 34, wherein: The beam sweeping is performed within a time window triggered by reception of the message.

39. The apparatus of claim 38, wherein: The time window is dynamically configured by the network entity.

40. The apparatus of claim 34, wherein: The repetitions are sent according to the beam indicated in the message.

41. The apparatus of claim 40, the memory and the at least one processor further configured to provide signaling to the UE indicating the repetition pattern.

42. The apparatus of claim 41, wherein: The repetition is performed within a time window triggered by the receipt of the message.

43. The apparatus of claim 42, wherein: The time window is dynamically configured by the network entity.

44. The apparatus of claim 34, wherein: The message includes an uplink grant scrambled by C-RNTI or MCS-C-RNTI.

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