WO2020063757A1

WO2020063757A1 - Apparatus and method for beam failure recovery in secondary cell

Info

Publication number: WO2020063757A1
Application number: PCT/CN2019/108171
Authority: WO
Inventors: Yushu Zhang; Qian Li; Gang Xiong
Original assignee: Intel Corporation
Priority date: 2018-09-27
Filing date: 2019-09-26
Publication date: 2020-04-02

Abstract

Provided herein is an apparatus and a method for beam failure recovery (BFR) in a secondary cell (SCell). An apparatus for a user equipment (UE) operating in a secondary cell includes a radio frequency (RF) interface; and processing circuitry coupled with the RF interface. The processing circuitry is to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; monitor communications from the access node for a second message that carries a BFR response; encode an identifier of the UE in a third message for transmission to the access node; and monitor communications from the access node for a fourth message that carries a collision handling response. Additionally, various BFR procedures applicable to the SCell are disclosed, including a contention based 4-step BFR procedure, a contention based 2-step BFR procedure, a contention free 4-step BFR procedure, and a contention free 2-step BFR procedure.

Description

APPARATUS AND METHOD FOR BEAM FAILURE RECOVERY IN SECONDARY CELL

Priority Declaration

This application is based on and claims priority to International Applications No. PCT/CN2018/108021 filed on September 27, 2018 and No. PCT/CN2019/074741 filed on February 09, 2019, both of which are incorporated herein by reference in their entirety.

Technical Field

Embodiments of the present disclosure generally relate to wireless communication, and in particular to apparatuses and methods for beam failure recovery (BFR) in a secondary cell (SCell) .

Background Art

Explosive wireless traffic growth leads to an urgent need of both of communication rate and capacity improvements. Multi-antenna technology has been introduced and studied to improve the rate and capacity of wireless communication. As the number of antennas is increasing, beam management is becoming more and more important. This disclosure will provide solutions for BFR in a SCell.

Summary

An aspect of the disclosure provides an apparatus for a user equipment (UE) operating in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; monitor communications from the access node for a second message that carries a BFR response; encode an identifier of the UE in a third message for transmission to the access node; and monitor communications from the access node for a fourth message that carries a collision handling response, and the RF interface is to transmit the first message and the third message to the access node and receive the second message and the fourth message from the access node.

An aspect of the disclosure provides an apparatus for an access node serving a user equipment (UE) in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: decode a first message carrying a beam failure recovery (BFR) request from the UE; encode a BFR response in a second message for transmission to the UE; decode a third message carrying an identifier of the UE; and encode a collision handling response in a fourth message for transmission to the UE, and the RF interface is to receive the first message and the third message from the UE and transmit the second message and the fourth message to the UE.

An aspect of the disclosure provides a computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of a user equipment (UE) operating in a secondary cell (SCell) , to cause the one or more processors to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; monitor communications from the access node for a second message that carries a BFR response; encode an identifier of the UE in a third message for transmission to the access node; and monitor communications from the access node for a fourth message that carries a collision handling response, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

An aspect of the disclosure provides a computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of a user equipment (UE) operating in a secondary cell (SCell) , to cause the one or more processors to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; and monitor communications from the access node for a second message that carries a BFR response, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Brief Description of the Drawings

Embodiments of the disclosure will be illustrated, by way of example and not limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

FIG. 1 illustrates an example architecture of a system of a network, in accordance with various embodiments of the disclosure.

FIG. 2 illustrates a message flow in a contention based 4-step BFR procedure between a user equipment (UE) and an access node (AN) in a SCell, in accordance with various embodiments of the disclosure.

FIG. 3 illustrates a message flow in a contention based 2-step BFR procedure between a UE and an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 4 illustrates a message flow in a contention free 4-step BFR procedure between a UE and an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 5 illustrates a message flow in a contention free 2-step BFR procedure between a UE and an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 6 illustrates a flowchart for a contention based 4-step BFR procedure performed at a UE in a SCell, in accordance with various embodiments of the disclosure.

FIG. 7 illustrates a flowchart for a contention based 2-step BFR procedure performed at a UE in a SCell, in accordance with various embodiments of the disclosure.

FIG. 8 illustrates a flowchart for a contention free 4-step BFR procedure performed at a UE in a SCell, in accordance with various embodiments of the disclosure.

FIG. 9 illustrates a flowchart for a contention free 2-step BFR procedure performed at a UE in a SCell, in accordance with various embodiments of the disclosure.

FIG. 10 illustrates a flowchart for a contention based 4-step BFR procedure performed at an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 11 illustrates a flowchart for a contention based 2-step BFR procedure performed at an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 12 illustrates a flowchart for a contention free 4-step BFR procedure performed at an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 13 illustrates a flowchart for a contention free 2-step BFR procedure performed at an AN in a SCell, in accordance with various embodiments of the disclosure.

FIG. 14 illustrates example components of a device in accordance with some embodiments of the disclosure.

FIG. 15 illustrates example interfaces of baseband circuitry in accordance with some embodiments of the disclosure.

FIG. 16 is a block diagram illustrating components, according to some example embodiments of the disclosure, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein.

Detailed Description of Embodiments

Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of the disclosure to others skilled in the art. However, it will be apparent to those skilled in the art that many alternate embodiments may be practiced using portions of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to those skilled in the art that alternate embodiments may be practiced without the specific details. In other instances, well known features may have been omitted or simplified in order to avoid obscuring the illustrative embodiments.

Further, various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

The phrases “in an embodiment” “in one embodiment” and “in some embodiments” are used repeatedly herein. The phrase generally does not refer to the same embodiment; however, it may. The terms “comprising, ” “having, ” and “including” are synonymous, unless the context dictates otherwise. The phrases “A or B” and “A/B” mean “ (A) , (B) , or (A and B) . ”

In 3GPP Rel-15, a beam failure recovery (BFR) mechanism (or procedure) has been specified. The BFR mechanism may include beam failure detection (BFD) , new beam identification (NBI) , beam failure recovery request (BFRQ) , and BFR response. BFD may be used to discover beam failure, which is based on measurement of downlink reference signal. NBI may be used to identify a new beam whose quality is above a threshold when beam failure happens. BFRQ may be used to inform the access network side (e.g., next generation NodeB (gNB) ) that beam failure happens as well as a new beam information is requested from a user equipment (UE) . BFR response is used to inform the UE that BFRQ is received by the gNB and a new beam will be applied.

For BFR in a primary cell (PCell) , when the UE detects a beam failure for all control channel resource sets (CORESETs) , the UE may transmit a BFRQ over a physical random access channel (PRACH) to inform the gNB new beam index (es) based on PRACH resource index (es) . Then the gNB can update beams for the CORESETs to maintain communication with the UE. Either a contention free PRACH (CF-PRACH) or a contention based PRACH (CB-PRACH) may be used for BFR in the PCell. For the CF-PRACH based BFR, the gNB may reserve some dedicate PRACH resources for a UE. Once the gNB detects the PRACH resources, the gNB can identify which UE declares beam failure. But the CF-PRACH based BFR would take large overhead as the number of UEs increases. In order to reduce the overhead, the CB-PRACH based BFR is proposed. For the CB-PRACH based BFR, the gNB may reserve some PRACH resources for a group of UEs or all the UEs. After receiving the PRACH resources for BFR, the gNB may need to handle collision between the UEs by subsequent messages (e.g. Message 3 and Message 4) during a random access procedure. Compared to the CF-PRACH based BFR, the CB-PRACH based BFR would take less overhead, but additional latency may be introduced for collision handling.

As described above, various BFR mechanisms have been specified for BFR in the PCell. Similar to the PCell, a beam failure may also occur in a secondary cell (SCell) . Currently mechanisms for BFR in the SCell are still in discussion, and how to effectively perform the BFR in SCell could be an issue. In the disclosure, embodiments related to contention based BFR procedures and contention free BFR procedures in the SCell will be discussed in detail.

FIG. 1 illustrates an example architecture of a system 100 of a network, in accordance with various embodiments. The following description is provided for an example system 100 that operates in conjunction with the Long Term Evolution (LTE) system standards and Fifth Generation (5G) or New Radio (NR) system standards as provided by Third Generation Partnership Project (3GPP) technical specifications. However, the example embodiments are not limited in this regard and the described embodiments may apply to other networks that benefit from the principles described herein, such as future 3GPP systems (e.g., Sixth Generation (6G) ) systems, IEEE 802.16 protocols (e.g., Wireless Metropolitan Area Network (WMAN) , Worldwide Interoperability for Microwave Access (WiMAX) , etc. ) , or the like.

As shown in FIG. 1, the system 100 includes UE 101a and UE 101b (collectively referred to as “UEs 101” or “UE 101” ) . In this example, UEs 101 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks) , but may also comprise any mobile or non-mobile computing device, such as consumer electronics devices, cellular phones, smartphones, feature phones, tablet computers, wearable computer devices, personal digital assistants (PDAs) , pagers, wireless handsets, desktop computers, laptop computers, in-vehicle infotainment (IVI) , in-car entertainment (ICE) devices, an Instrument Cluster (IC) , head-up display (HUD) devices, onboard diagnostic (OBD) devices, dashtop mobile equipment (DME) , mobile data terminals (MDTs) , Electronic Engine Management System (EEMS) , electronic/engine control units (ECUs) , electronic/engine control modules (ECMs) , embedded systems, microcontrollers, control modules, engine management systems (EMS) , networked or “smart” appliances, Machine-Type Communications (MTC) devices, Machine-to-Machine (M2M) , Internet of Things (IoT) devices, and/or the like.

In some embodiments, any of the UEs 101 may be IoT UEs, which may comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as M2M or MTC for exchanging data with an MTC server or device via a Public Land Mobile Network (PLMN) , Proximity-Based Service (ProSe) or Device-to-Device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure) , with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc. ) to facilitate the connections of the IoT network.

The UEs 101 may be configured to connect, for example, communicatively couple, with an access network (AN) or radio access network (RAN) 110. In embodiments, the RAN 110 may be a Next Generation RAN (NG RAN) or a 5G RAN, an Evolved Universal Terrestrial RAN (E-UTRAN) , or a legacy RAN, such as a Universal Terrestrial RAN (UTRAN) or GSM EDGE RAN (GERAN) . As used herein, the term “NG RAN” or the like may refer to a RAN 110 that operates in an NR or 5G system 100, and the term “E-UTRAN” or the like may refer to a RAN 110 that operates in an LTE or 4G system 100. The UEs 101 utilize connections (or channels) 103 and 104, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below) .

In this example, the

connections

103 and 104 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a Code-Division Multiple Access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP LTE protocol, a 5G protocol, a NR protocol, and/or any of the other communications protocols discussed herein. In embodiments, the UEs 101 may directly exchange communication data via a ProSe interface 105. The ProSe interface 105 may alternatively be referred to as a SL interface 105 and may comprise one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH) , a Physical Sidelink Shared Channel (PSSCH) , a Physical Sidelink Downlink Channel (PSDCH) , and a Physical Sidelink Broadcast Channel (PSBCH) .

The UE 101b is shown to be configured to access an access point (AP) 106 (also referred to as “Wireless Local Area Network (WLAN) node 106, ” “WLAN 106, ” “WLAN Termination (WT) 106, ” “WT 106” or the like) via connection 107. The connection 107 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, wherein the AP 106 would comprise a wireless fidelity

router. In this example, the AP 106 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below) . In various embodiments, the UE 101b, RAN 110, and AP 106 may be configured to utilize LTE-WLAN aggregation (LWA) operation and/or LTE/WLAN Radio Level Integration with IPsec Tunnel (LWIP) operation. The LWA operation may involve the UE 101b in RRC_CONNECTED being configured by a RAN node 111a-b to utilize radio resources of LTE and WLAN. LWIP operation may involve the UE 101b using WLAN radio resources (e.g., connection 107) via IPsec protocol tunneling to authenticate and encrypt packets (e.g., IP packets) sent over the connection 107. IPsec tunneling may include encapsulating the entirety of original IP packets and adding a new packet header, thereby protecting the original header of the IP packets.

The RAN 110 can include one or more Access Nodes (ANs) or

RAN nodes

111a and 111b (collectively referred to as “RAN nodes 111” or “RAN node 111” ) that enable the

connections

103 and 104. As used herein, the terms “access node, ” “access point, ” or the like may describe equipment that provides the radio baseband functions for data and/or voice connectivity between a network and one or more users. These access nodes can be referred to as Base Stations (BSs) , gNBs, RAN nodes, eNBs, NodeBs, Road Side Units (RSUs) , Transceiver Points (TRxPs) or Transmission Reception Points (TRPs) , and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell) . As used herein, the term “NG RAN node” or the like may refer to a RAN node 111 that operates in an NR or 5G system 100 (for example, a gNB) , and the term “E-UTRAN node” or the like may refer to a RAN node 111 that operates in an LTE or 4G system 100 (e.g., an eNB) . According to various embodiments, the RAN nodes 111 may be implemented as one or more of a dedicated physical device such as a macrocell base station, and/or a low power (LP) base station for providing femtocells, picocells or other like cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells.

In some embodiments, all or parts of the RAN nodes 111 may be implemented as one or more software entities running on server computers as part of a virtual network, which may be referred to as a Cloud RAN (CRAN) and/or a virtual baseband unit pool (vBBUP) . In these embodiments, the CRAN or vBBUP may implement a RAN function split, such as a Packet Data Convergence Protocol (PDCP) split wherein Radio Resource Control (RRC) and PDCP layers are operated by the CRAN/vBBUP and other L2 protocol entities are operated by individual RAN nodes 111; a Medium Access Control Layer (MAC) /Physical Layer (PHY) split wherein RRC, PDCP, Radio Link Control (RLC) , and MAC layers are operated by the CRAN/vBBUP and the PHY layer is operated by individual RAN nodes 111; or a “lower PHY” split wherein RRC, PDCP, RLC, MAC layers and upper portions of the PHY layer are operated by the CRAN/vBBUP and lower portions of the PHY layer are operated by individual RAN nodes 111. This virtualized framework allows the freed-up processor cores of the RAN nodes 111 to perform other virtualized applications.

In V2X scenarios one or more of the RAN nodes 111 may be or act as RSUs. The term “Road Side Unit” or “RSU” may refer to any transportation infrastructure entity used for V2X communications. An RSU may be implemented in or by a suitable RAN node or a stationary (or relatively stationary) UE, where an RSU implemented in or by a UE may be referred to as a “UE-type RSU, ” an RSU implemented in or by an eNB may be referred to as an “eNB-type RSU, ” an RSU implemented in or by a gNB may be referred to as a “gNB-type RSU, ” and the like. In one example, an RSU is a computing device coupled with radio frequency circuitry located on a roadside that provides connectivity support to passing vehicle UEs 101 (vUEs 101) . The RSU may also include internal data storage circuitry to store intersection map geometry, traffic statistics, media, as well as applications/software to sense and control ongoing vehicular and pedestrian traffic. The RSU may operate on the 5.9 GHz Direct Short Range Communications (DSRC) band to provide very low latency communications required for high speed events, such as crash avoidance, traffic warnings, and the like. Additionally or alternatively, the RSU may operate on the cellular V2X band to provide the aforementioned low latency communications, as well as other cellular communications services. Additionally or alternatively, the RSU may operate as a Wi-Fi hotspot (2.4 GHz band) and/or provide connectivity to one or more cellular networks to provide uplink and downlink communications. The computing device (s) and some or all of the radiofrequency circuitry of the RSU may be packaged in a weatherproof enclosure suitable for outdoor installation, and may include a network interface controller to provide a wired connection (e.g., Ethernet) to a traffic signal controller and/or a backhaul network.

Any of the RAN nodes 111 can terminate the air interface protocol and can be the first point of contact for the UEs 101. In some embodiments, any of the RAN nodes 111 can fulfill various logical functions for the RAN 110 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

In embodiments, the UEs 101 can be configured to communicate using OFDM communication signals with each other or with any of the RAN nodes 111 over a multicarrier communication channel in accordance with various communication techniques, such as, but not limited to, an Orthogonal Frequency Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications) , although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 111 to the UEs 101, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time-frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

According to various embodiments, the UEs 101, 102 and the RAN nodes 111, 112 communicate data (for example, transmit and receive) data over a licensed medium (also referred to as the “licensed spectrum” and/or the “licensed band” ) and an unlicensed shared medium (also referred to as the “unlicensed spectrum” and/or the “unlicensed band” ) . The licensed spectrum may include channels that operate in the frequency range of approximately 400 MHz to approximately 3.8 GHz, whereas the unlicensed spectrum may include the 5 GHz band.

To operate in the unlicensed spectrum, the UEs 101, 102 and the RAN nodes 111, 112 may operate using Licensed Assisted Access (LAA) , enhanced LAA (eLAA) , and/or further enhanced (feLAA) mechanisms. In these implementations, the UEs 101, 102 and the RAN nodes 111, 112 may perform one or more known medium-sensing operations and/or carrier-sensing operations in order to determine whether one or more channels in the unlicensed spectrum is unavailable or otherwise occupied prior to transmitting in the unlicensed spectrum. The medium/carrier sensing operations may be performed according to a listen-before-talk (LBT) protocol.

LBT is a mechanism whereby equipment (for example, UEs 101, 102, RAN nodes 111, 112, etc. ) senses a medium (for example, a channel or carrier frequency) and transmits when the medium is sensed to be idle (or when a specific channel in the medium is sensed to be unoccupied) . The medium sensing operation may include Clear Channel Assessment (CCA) , which utilizes at least Energy Detection (ED) to determine the presence or absence of other signals on a channel in order to determine if a channel is occupied or clear. This LBT mechanism allows cellular/LAA networks to coexist with incumbent systems in the unlicensed spectrum and with other LAA networks. ED may include sensing Radio Frequency (RF) energy across an intended transmission band for a period of time and comparing the sensed RF energy to a predefined or configured threshold.

Typically, the incumbent systems in the 5 GHz band are WLANs based on IEEE 802.11 technologies. WLAN employs a contention-based channel access mechanism, called Carrier Sense Multiple Access with collision avoidance (CSMA/CA) . Here, when a WLAN node (e.g., a mobile station (MS) such as UE 101 or 102, AP 106, or the like) intends to transmit, the WLAN node may first perform CCA before transmission. Additionally, a backoff mechanism is used to avoid collisions in situations where more than one WLAN node senses the channel as idle and transmits at the same time. The backoff mechanism may be a counter that is drawn randomly within the Contention Window Size (CWS) , which is increased exponentially upon the occurrence of collision and reset to a minimum value when the transmission succeeds. The LBT mechanism designed for LAA is somewhat similar to the CSMA/CA of WLAN. In some implementations, the LBT procedure for DL or UL transmission bursts including Physical Downlink Shared Channel (PDSCH) or Physical Uplink Shared Channel (PUSCH) transmissions, respectively, may have an LAA contention window that is variable in length between X and Y extended CCA (ECCA) slots, where X and Y are minimum and maximum values for the CWSs for LAA. In one example, the minimum CWS for an LAA transmission may be 9 microseconds (μs) ; however, the size of the CWS and a Maximum Channel Occupancy Time (MCOT) (for example, a transmission burst) may be based on governmental regulatory requirements.

The LAA mechanisms are built upon Carrier Aggregation (CA) technologies of LTE-Advanced systems. In CA, each aggregated carrier is referred to as a Component Carrier (CC) . A CC may have a bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz and a maximum of five CCs can be aggregated, and therefore, a maximum aggregated bandwidth is 100 MHz. In Frequency Division Duplex (FDD) systems, the number of aggregated carriers can be different for Downlink (DL) and Uplink (UL) , where the number of UL CCs is equal to or lower than the number of DL component carriers. In some cases, individual CCs can have a different bandwidth than other CCs. In Time Division Duplex (TDD) systems, the number of CCs as well as the bandwidths of each CC is usually the same for DL and UL.

CA also comprises individual serving cells to provide individual CCs. The coverage of the serving cells may differ, for example, because CCs on different frequency bands will experience different pathloss. A primary service cell or a primary cell (PCell) may provide a Primary Component Carrier (PCC) for both UL and DL, and may handle RRC and Non-Access Stratum (NAS) related activities. The other serving cells are referred to as secondary cells (SCells) , and each SCell may provide an individual SCC for both UL and DL. The SCCs may be added and removed as required, while changing the PCC may require the UE 101, 102 to undergo a handover. In LAA, eLAA, and feLAA, some or all of the SCells may operate in the unlicensed spectrum (referred to as “LAA SCells” ) , and the LAA SCells are assisted by a PCell operating in the licensed spectrum. When a UE is configured with more than one LAA SCell, the UE may receive UL grants on the configured LAA SCells indicating different PUSCH starting positions within a same subframe.

The PDSCH carries user data and higher-layer signaling to the UEs 101. The Physical Downlink Control Channel (PDCCH) carries information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 101 about the transport format, resource allocation, and Hybrid Automatic Repeat Request (HARQ) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 101b within a cell) may be performed at any of the RAN nodes 111 based on channel quality information fed back from any of the UEs 101. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 101.

The PDCCH uses Control Channel Elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as Resource Element Groups (REGs) . Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the Downlink Control Information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=1, 2, 4, or 8) .

Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced PDCCH (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced CCEs (ECCEs) . Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced REGs (EREGs) . An ECCE may have other numbers of EREGs in some situations.

The RAN nodes 111 may be configured to communicate with one another via interface 112. In embodiments where the system 100 is an LTE system, the interface 112 may be an X2 interface 112. The X2 interface may be defined between two or more RAN nodes 111 (e.g., two or more eNBs and the like) that connect to Evolved Packet Core (EPC) 120, and/or between two eNBs connecting to EPC 120. In some implementations, the X2 interface may include an X2 user plane interface (X2-U) and an X2 control plane interface (X2-C) . The X2-U may provide flow control mechanisms for user data packets transferred over the X2 interface, and may be used to communicate information about the delivery of user data between eNBs. For example, the X2-U may provide specific sequence number information for user data transferred from a Master eNB (MeNB) to an Secondary eNB (SeNB) ; information about successful in sequence delivery of PDCP Protocol Data Units (PDUs) to a UE 101 from an SeNB for user data; information of PDCP PDUs that were not delivered to a UE 101; information about a current minimum desired buffer size at the SeNB for transmitting to the UE user data; and the like. The X2-C may provide intra-LTE access mobility functionality, including context transfers from source to target eNBs, user plane transport control, etc.; load management functionality; as well as inter-cell interference coordination functionality.

In embodiments where the system 100 is a 5G or NR system, the interface 112 may be an Xn interface 112. The Xn interface is defined between two or more RAN nodes 111 (e.g., two or more gNBs and the like) that connect to 5G Core network (5GC) 120, between a RAN node 111 (e.g., a gNB) connecting to 5GC 120 and an eNB, and/or between two eNBs connecting to 5GC 120. In some implementations, the Xn interface may include an Xn user plane (Xn-U) interface and an Xn control plane (Xn-C) interface. The Xn-U may provide non-guaranteed delivery of user plane PDUs and support/provide data forwarding and flow control functionality. The Xn-C may provide management and error handling functionality, functionality to manage the Xn-C interface; mobility support for UE 101 in a connected mode (e.g., CM-CONNECTED) including functionality to manage the UE mobility for connected mode between one or more RAN nodes 111. The mobility support may include context transfer from an old (source) serving RAN node 111 to new (target) serving RAN node 111; and control of user plane tunnels between old (source) serving RAN node 111 to new (target) serving RAN node 111. A protocol stack of the Xn-U may include a transport network layer built on Internet Protocol (IP) transport layer, and a GPRS Tunnelling Protocol for User Plane (GTP-U) layer on top of a User Datagram Protocol (UDP) and/or IP layer (s) to carry user plane PDUs. The Xn-C protocol stack may include an application layer signaling protocol (referred to as Xn Application Protocol (Xn-AP) ) and a transport network layer that is built on SCTP. The SCTP may be on top of an IP layer, and may provide the guaranteed delivery of application layer messages. In the transport IP layer, point-to-point transmission is used to deliver the signaling PDUs. In other implementations, the Xn-U protocol stack and/or the Xn-C protocol stack may be same or similar to the user plane and/or control plane protocol stack (s) shown and described herein.

The RAN 110 is shown to be communicatively coupled to a core network-in this embodiment, core network (CN) 120. The CN 120 may comprise a plurality of network elements 122, which are configured to offer various data and telecommunications services to customers/subscribers (e.g., users of UEs 101) who are connected to the CN 120 via the RAN 110. The components of the CN 120 may be implemented in one physical node or separate physical nodes including components to read and execute instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) . In some embodiments, Network Functions Virtualization (NFV) may be utilized to virtualize any or all of the above-described network node functions via executable instructions stored in one or more computer-readable storage mediums (described in further detail below) . A logical instantiation of the CN 120 may be referred to as a network slice, and a logical instantiation of a portion of the CN 120 may be referred to as a network sub-slice. NFV architectures and infrastructures may be used to virtualize one or more network functions, alternatively performed by proprietary hardware, onto physical resources comprising a combination of industry-standard server hardware, storage hardware, or switches. In other words, NFV systems can be used to execute virtual or reconfigurable implementations of one or more EPC components/functions.

Generally, the application server 130 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc. ) . The application server 130 can also be configured to support one or more communication services (e.g., Voice-over-IP (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc. ) for the UEs 101 via the EPC 120.

In embodiments, the CN 120 may be a 5GC (referred to as “5GC 120” or the like) , and the RAN 110 may be connected with the CN 120 via an NG interface 113. In embodiments, the NG interface 113 may be split into two parts, an NG user plane (NG-U) interface 114, which carries traffic data between the RAN nodes 111 and a UPF, and the S1 control plane (NG-C) interface 115, which is a signaling interface between the RAN nodes 111 and Access and Mobility Management Functions (AMFs) . In other embodiments, the CN 120 may be an EPC. Where CN 120 is an EPC (referred to as “EPC 120” or the like) , the RAN 110 may be connected with the CN 120 via an S1 interface 113. In embodiments, the S1 interface 113 may be split into two parts, an S1 user plane (S1-U) interface 114, which carries traffic data between the RAN nodes 111 and the Serving Gateway (S-GW) , and the S1-MME interface 115, which is a signaling interface between the RAN nodes 111 and Mobility Management Entities (MMEs) .

The quantity of devices and/or networks illustrated in FIG. 1 is provided for explanatory purposes only. In practice, there may be additional devices and/or networks, fewer devices and/or networks, different devices and/or networks, or differently arranged devices and/or networks than illustrated in FIG. 1. Alternatively or additionally, one or more of the devices of system 100 may perform one or more functions described as being performed by another one or more of the devices of system 100. Furthermore, while “direct” connections are shown in FIG. 1, these connections should be interpreted as logical communication pathways, and in practice, one or more intervening devices (e.g., routers, gateways, modems, switches, hubs, etc. ) may be present.

FIG. 2 illustrates a message flow in a contention based 4-step BFR procedure between a user equipment (UE) and an access node (AN) in a SCell, in accordance with various embodiments of the disclosure. As shown in FIG. 2, the contention based 4-step BFR procedure may involve transmission and reception of four messages between the UE (e.g. UE 101a in FIG. 1) and the AN (e.g. RAN node 111a) serving the UE.

Message 1

When the UE determines a beam failure occurs in the SCell, the UE may encode a beam failure recovery (BFR) request in a first message (e.g. Message 1 in a 4-step random access procedure) and transmit the first message to the AN.

In some embodiments, for the contention based BFR procedure, some PRACH resources (referred to as “CB-PRACH” resources herein) for BFR can be configured for a group of UEs or all the UEs in the SCell by higher-layer signaling. When the UE detects a beam failure in the SCell, the UE may select a CB-PRACH resource to transmit a BFR request to the AN.

The CB-PRACH resource may be associated with a synchronization signal block (SSB) and/or Channel State Information Reference Signal (CSI-RS) . In an embodiment, one or more new candidate beams may be configured by the AN based on the SSB or the CSI-RS. In other words, the AN may inform the UE whether the synchronization signal in the SSB or the CSI-RS is used as a Reference Signal (RS) to identify the new candidate beams.

In some embodiments, the CB-PRACH resources may be dedicated to the BFR procedure. Also, a CB-PRACH resource may be associated with a new candidate beam, which means that a new beam index may be implicitly indicated by a PRACH resource index. For example, the UE can select a CB-PRACH resource to carry the BFR request if a beam quality for a DL RS associated with the CB-PRACH is above a predetermined threshold, and then the AN can select a new beam based on the PRACH resource index of the CB-PRACH resource carrying the BFR request from the UE.

Alternatively, for the contention based BFR procedure, some PUCCH resources (referred to as “CB-PUCCH” resources herein) for BFR can be configured for a group of UEs or all the UEs in the SCell by higher-layer signaling, where each PUCCH resource can be associated with a SSB or a CSI-RS. The UE may use a CB-PUCCH resource to transmit the BFR request to the AN.

The CB-PUCCH resources may also be dedicated to the BFR procedure. Also, a CB-PUCCH resource may be associated with a new candidate beam. For example, a mapping relationship between each new candidate beam and a corresponding CB-PUCCH resource may be predetermined and known at both the UE and the AN. After the UE detects a beam failure in the SCell and identifies a new candidate beam, the UE may transmit a BFR request by a CB-PUCCH resource associated with the new candidate beam.

Message 2

When the AN receives the BFR request from the UE, the AN may decode the BFR request and then transmit a BFR response in a second message (e.g. Message 2 in the 4-step random access procedure) to UE. In an embodiment, the AN may transmit the second message carrying the BFR response over a PDCCH in K slots after receiving the first message from the UE, where K is predefined, e.g. K=0 or K=4, or configured by higher-layer signaling. The PDCCH may be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR may be associated with the CB-PRACH resource or the CB- PUCCH resource carrying the BFR request. Accordingly, the UE may monitor the dedicated SS-BFR K slots after the transmission of the BFRQ to receive the BFR response.

In an embodiment, the PDCCH may be based on a DCI format 0_0 only or either DCI format 0_0 or DCI format 0_1. In an embodiment, the PDCCH may be based on a DCI format scrambled by a cell radio network temporary ID (C-RNTI) of the UE if the C-RNTI of the UE is carried together with the BFR request in the first message over the CB-PRACH or CB-PUCCH resource. Alternatively, the PDCCH may be based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CB-PRACH resource.

In an embodiment, the SS-BFR may be Quasi-Co-Located (QCLed) with a SSB or a CSI-RS associated with the CB-PRACH resource or the CB-PUCCH resource. In an embodiment, the UE may retransmit the BFR request when the BFR response is not received within a time window. In an embodiment, the time window may be predefined or configured by higher-layer signaling. In an embodiment, the UE may be allowed to perform up to a number of retransmission of the BFRQ. The number of retransmission may be predefined or configured by higher-layer signaling.

In an embodiment, all the SS-BFR could be tied to one CORESET (CORESET-BFR) . The UE may not monitor the SS-BFR/CORESET-BFR before the UE transmits the BFR request or after the BFR procedure is finished. The UE shall expect Transmission Configuration Indication (TCI) should not be configured for the CORESET-BFR.

Message 3 and Message 4

For the contention based BFR procedure, it should be expected that collision between UEs may happen and a collision handling procedure may be required. Thus after receiving the BFR response, the UE may encode a contention resolution identifier (ID) in a third message and transmit the third message (e.g. Message 3 in the 4-step random access procedure) to the AN. Then the UE may monitor a collision handling response in a fourth message (e.g. Message 4 in the 4-step random access procedure) from the AN to determine the UE is identified by the AN. For example, in Message 3, the UE may transmit a UE ID (e.g. C-RNTI) to the AN and monitor a collision handling response from the AN. If the UE detects the UE ID from the collision handling response correctly, the UE may consider that the BFR request is correctly received by the AN.

In the third message, in addition to the UE ID, the UE may also transmit failed Component Carrier (CC) index (es) and/or information associated with a new candidate beam. In an embodiment, the information associated with the new candidate beam may include a SSB/CSI-RS resource index, a beam index or a quality indicator of the new candidate beam. The quality indicator may include Layer 1 reference signal receiving power (L1-RSRP) , Layer 1 signal to interference plus noise (L1-SINR) or Layer 1 reference signal receiving quality (L1-RSRQ) . Which metric is used as the beam quality indicator may be predefined or configured by higher-layer signaling.

In an embodiment, a dedicated logical channel can be reserved to carry the BFR information in the third message, as shown in Table 1.

Table 1: An example for Logical Channel ID (LCID) indication

In addition, possible MAC Channel Element (MAC CE) formats for the BFR information are illustrated below in Table 2 to Table 4, where ‘R” stands for a reserved bit.

Table 2: MAC CE format for BFR information (option 1)

Table 3: MAC CE format for BFR information (option 2)

Table 4: MAC CE format for BFR information (option 3)

As illustrated in the above Table 2 to Table 4, the content and format of the third message may be specified depending on practical requirements or restrictions. The third message may carry the contention resolution ID, the failed Component Carrier (CC) index (es) and/or information associated with a new candidate beam, and accordingly the fourth message may carry the collision handling response and/or confirmation with the failed CC index (es) and the new candidate beam.

In some embodiments, the first message and the third message may be combined in a same message for transmission to the AN over the CB-PRACH resource or the CB-PUCCH resource, and accordingly the second message and the fourth message may be received in a same message from the AN. In this way, the latency for beam failure recovery may be reduced.

FIG. 3 illustrates a message flow in a contention based 2-step BFR procedure between a user equipment (UE) and an access node (AN) in a SCell, in accordance with various embodiments of the disclosure. As shown in FIG. 3, the contention based 2-step BFR procedure may only involve transmission and reception of two messages (Message A and Message B) between the UE and the AN.

For the UE in RRC_CONNECTED mode, Message A may be a combination of the first message and the third message in FIG. 2, and Message B may be a combination of the second message and the fourth message in FIG. 2. Thus detailed description about Message A and Message B will not be repeated herein. It should be noted that when the UE is informed to switch and fall back to a 4-step random access procedure, Message 3 and Message 4 may also be needed after Message B to handle collision.

In addition to the above illustrated contention based BFR procedures, a contention free 4-step BFR procedure and a contention free 2-step BFR procedure may also be applied to perform the BFR in the SCell.

For the contention free 4-step BFR procedure, when detecting a beam failure in the SCell, the UE may transmit a first message carrying a BFR request to the AN over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

The CF-PRACH resource or the CF-PUCCH resource is reserved only for the UE by the AN. After receiving the BFR request over the CF-PRACH resource or the CF-PUCCH resource, the AN can identify which UE declares beam failure. In other words, there is no collision between the UEs. For CF-PUCCH based BFR, the UE ID, i.e. C-RNTI, can be carried by the CF-PUCCH. After receiving a PDCCH scrambled by C-RNTI, the UE can consider that the BFR request is successfully received by the AN. Likewise, for CF-PRACH based BFR, after receiving a PDCCH scrambled by RA-RNTI, the UE can consider the BFR request is successfully received by the AN. So after the UE receives the BFR response from the AN, the BFR procedure may be completed. That is, the BFR procedure may only need the first message to send the BFR request and the second message to provide the BFR response. The first message and the second message in the contention free 4-step BFR procedure in FIG. 4 may be the same as the first message and the second message in the contention based 4-step BFR procedure in FIG. 2, so detailed description about these messages will be omitted here.

In some situations, more information may be desired by the AN e.g. in order to select a new beam appropriate to maintain communication with the UE. Therefore, the contention free 4-step BFR procedure as shown in FIG. 4 may also include a third message and a fourth message. For example, the third message may carry failed Component Carrier (CC) index (es) and/or information associated with a new candidate beam, and accordingly the fourth message may carry confirmation with the failed CC index (es) and the new candidate beam. In an embodiment, the information associated with the new candidate beam may include a SSB/CSI-RS resource index, a beam index or a quality indicator (e.g. L1-RSRP, L1-SINR, or L1-RSRQ) of the new candidate beam.

In some embodiments, the third message may be transmitted by the UE over a physical uplink shared channel (PUSCH) in response to an uplink grant from the AN. For example, after confirming reception of the BFR request, the AN may inform the UE to provide the failed Component Carrier (CC) index (es) and/or information associated with new candidate beams. Then based on the failed Component Carrier (CC) index (es) and/or information associated with new candidate beams, the AN can select a new beam from the new candidate beams to continue the communication with the UE.

In some embodiments, the first message and the third message in the message flow of FIG. 4 may be combined in a same message for transmission to the AN over the CF-PRACH resource or the CF-PUCCH resource, and accordingly the second message and the fourth message may be received in a same message from the AN. In this way, the latency for beam failure recovery may be reduced.

As shown in FIG. 5, Message A may correspond to a combination of Message 1 and Message 2 in FIG. 4 and Message B may correspond to a combination of Message 3 and Message 4 in FIG. 4. Thus detailed description about FIG. 5 will be omitted here.

Further to the above discussed message flows for various BFR procedures in the SCell, the BFR procedures at the UE side and the AN side will be described separately with reference to FIG. 6 to FIG. 13.

At 610, the UE may determine a beam failure occurs in the SCell, e.g., based on measurement of downlink reference signal.

At 620, the UE may transmit a first message carrying a BFR request to an AN serving the UE.

At 630, the UE may monitor communications from the AN for a second message that carries a BFR response.

At 640, the UE may transmit a third message carrying a contention resolution ID, e.g. C-RNTI, to the AN.

At 650, the UE may monitor communications from the AN for a fourth message that carries a collision handling response.

Details about the first to fourth messages have been discussed with reference to the message flow in FIG. 2 and will be omitted here for conciseness.

At 710, the UE may determine a beam failure occurs in the SCell, e.g., based on measurement of downlink reference signal.

At 720, the UE may transmit a first message carrying a BFR request, a UE ID and a failed CC index and/or information associated with a new candidate beam to an AN serving the UE.

At 730, the UE may monitor communications from the AN for a second message that carries a BFR response and a collision handling response.

Details about the first to second messages have been discussed with reference to the message flow in FIG. 3 and will be omitted here for conciseness.

At 810, the UE may determine a beam failure occurs in the SCell, e.g., based on measurement of downlink reference signal.

At 820, the UE may transmit a first message carrying a BFR request to an AN serving the UE.

At 830, the UE may monitor communications from the AN for a second message that carries a BFR response.

At 840, the UE may transmit a third message carrying a failed CC index and/or information associated with a new candidate beam to the AN.

At 850, the UE may monitor communications from the AN for a fourth message that carries a confirmation with the new candidate beam.

Details about the first to fourth messages have been discussed with reference to the message flow in FIG. 4 and will be omitted here for conciseness.

At 910, the UE may determine a beam failure occurs in the SCell, e.g., based on measurement of downlink reference signal.

At 920, the UE may transmit a first message carrying a BFR request, a fail CC index and/or information associated with a new candidate beam to an AN serving the UE.

At 930, the UE may monitor communications from the AN for a second message that carries a BFR response and a confirmation with the new candidate beam.

Details about the first to second messages have been discussed with reference to the message flow in FIG. 5 and will be omitted here for conciseness.

At 1010, the AN may decode a first message carrying a BFR request from a UE.

At 1020, the AN may transmit a second message carrying a BFR response to the UE.

At 1030, the AN may decode a third message carrying a contention resolution ID from the UE.

At 1040, the AN may transmit a fourth message carrying a collision handling response to the UE.

At 1110, the AN may decode a first message carrying a BFR request, a UE ID and a failed CC index and/or information associated with a new candidate beam from a UE.

At 1120, the AN may transmit a second message carrying a BFR response and a collision handling response to the UE.

At 1210, the AN may decode a first message carrying a BFR request from a UE.

At 1220, the AN may transmit a second message carrying a BFR response to the UE.

At 1230, the AN may decode a third message carrying a failed CC index and/or information associated with a new candidate beam from the UE.

At 1240, the AN may transmit a fourth message carrying a confirmation with the new candidate beam to the UE.

At 1310, the AN may decode a first message carrying a BFR request, a fail CC index and/or information associated with a new candidate beam from a UE.

At 1320, the AN may transmit a second message carrying a BFR response and a confirmation with the new candidate beam to the UE.

FIG. 14 illustrates example components of a device 1400 in accordance with some embodiments. In some embodiments, the device 1400 may include application circuitry 1402, baseband circuitry 1404, Radio Frequency (RF) circuitry 1406, front-end module (FEM) circuitry 1408, one or more antennas 1410, and power management circuitry (PMC) 1412 coupled together at least as shown. The components of the illustrated device 1400 may be included in a UE or a RAN node. In some embodiments, the device 1400 may include less elements (e.g., a RAN node may not utilize application circuitry 1402, and instead include a processor/controller to process IP data received from an EPC) . In some embodiments, the device 1400 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations) .

The application circuitry 1402 may include one or more application processors. For example, the application circuitry 1402 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor (s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc. ) . The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 1400. In some embodiments, processors of application circuitry 1402 may process IP data packets received from an EPC.

The baseband circuitry 1404 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1404 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 1406 and to generate baseband signals for a transmit signal path of the RF circuitry 1406. Baseband processing circuitry 1404 may interface with the application circuitry 1402 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1406. For example, in some embodiments, the baseband circuitry 1404 may include a third generation (3G) baseband processor 1404A, a fourth generation (4G) baseband processor 1404B, a fifth generation (5G) baseband processor 1404C, or other baseband processor (s) 1404D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G) , sixth generation (6G) , etc. ) . The baseband circuitry 1404 (e.g., one or more of baseband processors 1404A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1406. In other embodiments, some or all of the functionality of baseband processors 1404A-D may be included in modules stored in the memory 1404G and executed via a Central Processing Unit (CPU) 1404E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc.

In some embodiments, modulation/demodulation circuitry of the baseband circuitry 1404 may include Fast-Fourier Transform (FFT) , precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 1404 may include convolution, tail-biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 1404 may include one or more audio digital signal processor (s) (DSP) 1404F. The audio DSP (s) 1404F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 1404 and the application circuitry 1402 may be implemented together such as, for example, on a system on a chip (SOC) .

In some embodiments, the baseband circuitry 1404 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 1404 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry 1404 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

RF circuitry 1406 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 1406 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1406 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1408 and provide baseband signals to the baseband circuitry 1404. RF circuitry 1406 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1404 and provide RF output signals to the FEM circuitry 1408 for transmission.

In some embodiments, the receive signal path of the RF circuitry 1406 may include mixer circuitry 1406a, amplifier circuitry 1406b and filter circuitry 1406c. In some embodiments, the transmit signal path of the RF circuitry 1406 may include filter circuitry 1406c and mixer circuitry 1406a. RF circuitry 1406 may also include synthesizer circuitry 1406d for synthesizing a frequency for use by the mixer circuitry 1406a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 1406a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1408 based on the synthesized frequency provided by synthesizer circuitry 1406d. The amplifier circuitry 1406b may be configured to amplify the down-converted signals and the filter circuitry 1406c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 1404 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 1406a of the receive signal path may include passive mixers, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 1406a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 1406d to generate RF output signals for the FEM circuitry 1408. The baseband signals may be provided by the baseband circuitry 1404 and may be filtered by filter circuitry 1406c.

In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively.

In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection) . In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may be configured for super-heterodyne operation.

In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 1406 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 1404 may include a digital baseband interface to communicate with the RF circuitry 1406.

In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 1406d may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 1406d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

The synthesizer circuitry 1406d may be configured to synthesize an output frequency for use by the mixer circuitry 1406a of the RF circuitry 1406 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 1406d may be a fractional N/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO) , although that is not a requirement. Divider control input may be provided by either the baseband circuitry 1404 or the applications processor 1402 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1402.

Synthesizer circuitry 1406d of the RF circuitry 1406 may include a divider, a delay-locked loop (DLL) , a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA) . In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 1406d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO) . In some embodiments, the RF circuitry 1406 may include an IQ/polar converter.

FEM circuitry 1408 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1410, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1406 for further processing. FEM circuitry 1408 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1406 for transmission by one or more of the one or more antennas 1410. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 1406, solely in the FEM 1408, or in both the RF circuitry 1406 and the FEM 1408.

In some embodiments, the FEM circuitry 1408 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 1406) . The transmit signal path of the FEM circuitry 1408 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1406) , and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1410) .

In some embodiments, the PMC 1412 may manage power provided to the baseband circuitry 1404. In particular, the PMC 1412 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 1412 may often be included when the device 1400 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 1412 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

While FIG. 14 shows the PMC 1412 coupled only with the baseband circuitry 1404. However, in other embodiments, the PMC 1412 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 1402, RF circuitry 1406, or FEM 1408.

In some embodiments, the PMC 1412 may control, or otherwise be part of, various power saving mechanisms of the device 1400. For example, if the device 1400 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 1400 may power down for brief intervals of time and thus save power.

If there is no data traffic activity for an extended period of time, then the device 1400 may transition off to an RRC_Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 1400 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 1400 may not receive data in this state, in order to receive data, it must transition back to RRC_Connected state.

An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours) . During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

Processors of the application circuitry 1402 and processors of the baseband circuitry 1404 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 1404, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 1404 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers) . As referred to herein, Layer 3 may include a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may include a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may include a physical (PHY) layer of a UE/RAN node, described in further detail below.

FIG. 15 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 1404 of FIG. 14 may include processors 1404A-1404E and a memory 1404G utilized by said processors. Each of the processors 1404A- 1404E may include a memory interface, 1504A-1504E, respectively, to send/receive data to/from the memory 1404G.

The baseband circuitry 1404 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 1512 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 1404) , an application circuitry interface 1514 (e.g., an interface to send/receive data to/from the application circuitry 1402 of FIG. 14) , an RF circuitry interface 1516 (e.g., an interface to send/receive data to/from RF circuitry 1406 of FIG. 14) , a wireless hardware connectivity interface 1518 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components,

components (e.g.,

Low Energy) ,

components, and other communication components) , and a power management interface 1520 (e.g., an interface to send/receive power or control signals to/from the PMC 1412) .

FIG. 16 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein. Specifically, FIG. 16 shows a diagrammatic representation of hardware resources 1600 including one or more processors (or processor cores) 1610, one or more memory/storage devices 1620, and one or more communication resources 1630, each of which may be communicatively coupled via a bus 1640. For embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 1602 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources 1600.

The processors 1610 (e.g., a central processing unit (CPU) , a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU) , a digital signal processor (DSP) such as a baseband processor, an application specific integrated circuit (ASIC) , a radio-frequency integrated circuit (RFIC) , another processor, or any suitable combination thereof) may include, for example, a processor 1612 and a processor 1614.

The memory/storage devices 1620 may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices 1620 may include, but are not limited to any type of volatile or non-volatile memory such as dynamic random access memory (DRAM) , static random-access memory (SRAM) , erasable programmable read-only memory (EPROM) , electrically erasable programmable read-only memory (EEPROM) , Flash memory, solid-state storage, etc.

The communication resources 1630 may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices 1604 or one or more databases 1606 via a network 1608. For example, the communication resources 1630 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB) ) , cellular communication components, NFC components,

components (e.g.,

Low Energy) ,

components, and other communication components.

Instructions 1650 may include software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors 1610 to perform any one or more of the methodologies discussed herein. The instructions 1650 may reside, completely or partially, within at least one of the processors 1610 (e.g., within the processor’s cache memory) , the memory/storage devices 1620, or any suitable combination thereof. Furthermore, any portion of the instructions 1650 may be transferred to the hardware resources 1600 from any combination of the peripheral devices 1604 or the databases 1606. Accordingly, the memory of processors 1610, the memory/storage devices 1620, the peripheral devices 1604, and the databases 1606 are examples of computer-readable and machine-readable media.

The following paragraphs describe examples of various embodiments.

Example 1 includes an apparatus for a user equipment (UE) operating in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; monitor communications from the access node for a second message that carries a BFR response; encode an identifier of the UE in a third message for transmission to the access node; and monitor communications from the access node for a fourth message that carries a collision handling response, and the RF interface is to transmit the first message and the third message to the access node and receive the second message and the fourth message from the access node.

Example 2 includes the apparatus of Example 1, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 3 includes the apparatus of Example 2, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 4 includes the apparatus of Example 2, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 5 includes the apparatus of Example 2, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 6 includes the apparatus of Example 2, wherein: the first message and the third message are combined in a same message for transmission to the access node over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are received in a same message from the access node.

Example 7 includes the apparatus of Example 1, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 8 includes the apparatus of any of Examples 1-7, wherein the processing circuitry is further to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message or the third message.

Example 9 includes the apparatus of Example 8, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 10 includes an apparatus for a user equipment (UE) operating in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: determine a beam failure occurs in the secondary cell; encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; and monitor communications from the access node for a second message that carries a BFR response, and the RF interface is to transmit the first message to the access node and receive the second message from the access node.

Example 11 includes the apparatus of Example 10, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 12 includes the apparatus of Example 11, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 13 includes the apparatus of Example 11, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 14 includes the apparatus of Example 11, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 15 includes the apparatus of any of Examples 10-14, wherein the processing circuitry is further to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message.

Example 16 includes the apparatus of any of Examples 10-14, wherein the processing circuitry is further to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in a third message for transmission to the access node.

Example 17 includes the apparatus of Example 16, wherein the third message is to be transmitted over a physical uplink shared channel (PUSCH) in response to an uplink grant from the access node.

Example 18 includes the apparatus of any of Examples 15-17, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 19 includes an apparatus for an access node serving a user equipment (UE) in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: decode a first message carrying a beam failure recovery (BFR) request from the UE; encode a BFR response in a second message for transmission to the UE; decode a third message carrying an identifier of the UE; and encode a collision handling response in a fourth message for transmission to the UE, and the RF interface is to receive the first message and the third message from the UE and transmit the second message and the fourth message to the UE.

Example 20 includes the apparatus of Example 19, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 21 includes the apparatus of Example 20, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 22 includes the apparatus of Example 20, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 23 includes the apparatus of Example 20, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 24 includes the apparatus of Example 19, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 25 includes the apparatus of Example 20, wherein: the first message and the third message are received from the UE in a same message over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are combined in a same message for transmission to the UE.

Example 26 includes the apparatus of any of Examples 19-25, wherein: a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message, and the processing circuitry is further to encode a confirmation with the new candidate beam in the second message; or a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the third message, and the processing circuitry is further to encode a confirmation with the new candidate beam in the fourth message.

Example 27 includes the apparatus of Example 26, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 28 includes the apparatus of Example 20, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 29 includes the apparatus of Example 28, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 30 includes the apparatus of Example 29, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 31 includes the apparatus of Example 28, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CB-PRACH resource or the CB-PUCCH resource.

Example 32 includes the apparatus of Example 28, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CB-PRACH resource.

Example 33 includes an apparatus for an access node serving a user equipment (UE) in a secondary cell, comprising: a radio frequency (RF) interface; and processing circuitry coupled with the RF interface, wherein the processing circuitry is to: decode a first message carrying a beam failure recovery (BFR) request from the UE; and encode a BFR response in a second message for transmission to the UE, and the RF interface is to receive the first message from the UE and transmit the second message to the UE.

Example 34 includes the apparatus of Example 33, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 35 includes the apparatus of Example 34, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 36 includes the apparatus of Example 34, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 37 includes the apparatus of Example 34, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 38 includes the apparatus of any of Examples 33-37, wherein a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message and the processing circuitry is further to encode a confirmation with the new candidate beam in the second message.

Example 39 includes the apparatus of any of Examples 33-37, wherein the processing circuitry is further to inform the UE to transmit a failed Component Carrier (CC) index or information associated with a new candidate beam to the access node.

Example 40 includes the apparatus of Example 38 or 39, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 41 includes the apparatus of Example 34, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 42 includes the apparatus of Example 41, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 43 includes the apparatus of Example 42, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 44 includes the apparatus of Example 41, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CF-PRACH resource or the CF-PUCCH resource.

Example 45 includes the apparatus of Example 41, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CF-PRACH resource.

Example 46 includes a method performed at a user equipment (UE) operating in a secondary cell, the method comprising: determining a beam failure occurs in the secondary cell; encoding a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; monitoring communications from the access node for a second message that carries a BFR response; encoding an identifier of the UE in a third message for transmission to the access node; and monitoring communications from the access node for a fourth message that carries a collision handling response.

Example 47 includes the method of Example 46, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 48 includes the method of Example 47, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 49 includes the method of Example 47, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 50 includes the method of Example 47, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 51 includes the method of Example 47, wherein: the first message and the third message are combined in a same message for transmission to the access node over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are received in a same message from the access node.

Example 52 includes the method of Example 46, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 53 includes the method of any of Examples 46-52, further comprising encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message or the third message.

Example 54 includes the method of Example 53, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 55 includes a method performed at a user equipment (UE) operating in a secondary cell, the method comprising: determining a beam failure occurs in the secondary cell; encoding a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; and monitoring communications from the access node for a second message that carries a BFR response.

Example 56 includes the method of Example 55, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 57 includes the method of Example 56, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 58 includes the method of Example 56, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 59 includes the method of Example 56, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 60 includes the method of any of Examples 55-59, further comprising encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message.

Example 61 includes the method of any of Examples 55-59, further comprising encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in a third message for transmission to the access node.

Example 62 includes the method of Example 61, wherein the third message is to be transmitted over a physical uplink shared channel (PUSCH) in response to an uplink grant from the access node.

Example 63 includes the method of any of Examples 60-62, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 64 includes a method performed at an access node serving a user equipment (UE) in a secondary cell, the method comprising: decoding a first message carrying a beam failure recovery (BFR) request from the UE; encoding a BFR response in a second message for transmission to the UE; decoding a third message carrying an identifier of the UE; and encoding a collision handling response in a fourth message for transmission to the UE.

Example 65 includes the method of Example 64, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 66 includes the method of Example 65, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 67 includes the method of Example 65, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 68 includes the method of Example 65, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 69 includes the method of Example 65, wherein: the first message and the third message are received from the UE in a same message over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are combined in a same message for transmission to the UE.

Example 70 includes the method of Example 64, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 71 includes the method of any of Examples 64-70, wherein: a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message, and the method further comprises encoding a confirmation with the new candidate beam in the second message; or a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the third message, and the method further comprises encoding a confirmation with the new candidate beam in the fourth message.

Example 72 includes the method of Example 71, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 73 includes the method of Example 65, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 74 includes the method of Example 73, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 75 includes the method of Example 74, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 76 includes the method of Example 73, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CB-PRACH resource or the CB-PUCCH resource.

Example 77 includes the method of Example 73, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CB-PRACH resource.

Example 78 includes a method performed at an access node serving a user equipment (UE) in a secondary cell, the method comprising: decoding a first message carrying a beam failure recovery (BFR) request from the UE; and encoding a BFR response in a second message for transmission to the UE.

Example 79 includes the method of Example 78, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 80 includes the method of Example 79, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 81 includes the method of Example 79, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 82 includes the method of Example 79, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 83 includes the method of any of Examples 78-82, wherein a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message and the method further comprises encoding a confirmation with the new candidate beam in the second message.

Example 84 includes the method of any of Examples 78-82, further comprising informing the UE to transmit a failed Component Carrier (CC) index or information associated with a new candidate beam to the access node.

Example 85 includes the method of Example 83 or 84, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 86 includes the method of Example 79, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 87 includes the method of Example 86, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 88 includes the method of Example 87, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 89 includes the method of Example 86, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CF-PRACH resource or the CF-PUCCH resource.

Example 90 includes the method of Example 86, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CF-PRACH resource.

Example 91 includes an apparatus for a user equipment (UE) operating in a secondary cell, the apparatus comprising: means for determining a beam failure occurs in the secondary cell; means for encoding a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; means for monitoring communications from the access node for a second message that carries a BFR response; means for encoding an identifier of the UE in a third message for transmission to the access node; and means for monitoring communications from the access node for a fourth message that carries a collision handling response.

Example 92 includes the apparatus of Example 91, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 93 includes the apparatus of Example 92, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 94 includes the apparatus of Example 92, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 95 includes the apparatus of Example 92, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 96 includes the apparatus of Example 92, wherein: the first message and the third message are combined in a same message for transmission to the access node over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are received in a same message from the access node.

Example 97 includes the apparatus of Example 91, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 98 includes the apparatus of any of Examples 91-97, further comprising means for encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message or the third message.

Example 99 includes the apparatus of Example 98, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 100 includes an apparatus for a user equipment (UE) operating in a secondary cell, the apparatus comprising: means for determining a beam failure occurs in the secondary cell; means for encoding a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; and means for monitoring communications from the access node for a second message that carries a BFR response.

Example 101 includes the apparatus of Example 100, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 102 includes the apparatus of Example 101, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 103 includes the apparatus of Example 101, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 104 includes the apparatus of Example 101, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 105 includes the apparatus of any of Examples 100-104, further comprising means for encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message.

Example 106 includes the apparatus of any of Examples 100-104, further comprising means for encoding a failed Component Carrier (CC) index or information associated with a new candidate beam in a third message for transmission to the access node.

Example 107 includes the apparatus of Example 106, wherein the third message is to be transmitted over a physical uplink shared channel (PUSCH) in response to an uplink grant from the access node.

Example 108 includes the apparatus of any of Examples 105-107, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 109 includes an apparatus for an access node serving a user equipment (UE) in a secondary cell, the apparatus comprising: means for decoding a first message carrying a beam failure recovery (BFR) request from the UE; means for encoding a BFR response in a second message for transmission to the UE; means for decoding a third message carrying an identifier of the UE; and means for encoding a collision handling response in a fourth message for transmission to the UE.

Example 110 includes the apparatus of Example 109, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.

Example 111 includes the apparatus of Example 110, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 112 includes the apparatus of Example 110, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.

Example 113 includes the apparatus of Example 110, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 114 includes the apparatus of Example 110, wherein: the first message and the third message are received from the UE in a same message over the CB-PRACH resource or the CB-PUCCH resource; and the second message and the fourth message are combined in a same message for transmission to the UE.

Example 115 includes the apparatus of Example 109, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.

Example 116 includes the apparatus of any of Examples 109-115, wherein: a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message, and the apparatus further comprises means for encoding a confirmation with the new candidate beam in the second message; or a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the third message, and the apparatus further comprises means for encoding a confirmation with the new candidate beam in the fourth message.

Example 117 includes the apparatus of Example 116, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 118 includes the apparatus of Example 110, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 119 includes the apparatus of Example 118, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 120 includes the apparatus of Example 119, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CB-PRACH resource or the CB-PUCCH resource.

Example 121 includes the apparatus of Example 118, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CB-PRACH resource or the CB-PUCCH resource.

Example 122 includes the apparatus of Example 118, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CB-PRACH resource.

Example 123 includes an apparatus for an access node serving a user equipment (UE) in a secondary cell, the apparatus comprising: means for decoding a first message carrying a beam failure recovery (BFR) request from the UE; and means for encoding a BFR response in a second message for transmission to the UE.

Example 124 includes the apparatus of Example 123, wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.

Example 125 includes the apparatus of Example 124, wherein the CF-PRACH resource or the CF-PUCCH resource is dedicated to a BFR procedure at the UE.

Example 126 includes the apparatus of Example 124, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a new candidate beam.

Example 127 includes the apparatus of Example 124, wherein the CF-PRACH resource or the CF-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .

Example 128 includes the apparatus of any of Examples 123-127, wherein a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message and the apparatus further comprises means for encoding a confirmation with the new candidate beam in the second message.

Example 129 includes the apparatus of any of Examples 123-127, further comprising means for informing the UE to transmit a failed Component Carrier (CC) index or information associated with a new candidate beam to the access node.

Example 130 includes the apparatus of Example 128 or 129, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.

Example 131 includes the apparatus of Example 124, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.

Example 132 includes the apparatus of Example 131, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 133 includes the apparatus of Example 132, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CF-PRACH resource or the CF-PUCCH resource.

Example 134 includes the apparatus of Example 131, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CF-PRACH resource or the CF-PUCCH resource.

Example 135 includes the apparatus of Example 131, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CF-PRACH resource.

Example 136 includes a computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of a user equipment (UE) operating in a secondary cell, to cause the one or more processors to perform the method of any of Examples 46 to 77.

Example 137 includes a computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of an access node serving a user equipment (UE) in a secondary cell, to cause the one or more processors to perform the method of any of Examples 78 to 90.

Although certain embodiments have been illustrated and described herein for purposes of description, a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments described herein be limited only by the appended claims and the equivalents thereof.

Claims

An apparatus for a user equipment (UE) operating in a secondary cell, comprising:

a radio frequency (RF) interface; and

processing circuitry coupled with the RF interface,

wherein the processing circuitry is to:

determine a beam failure occurs in the secondary cell;

encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE;

monitor communications from the access node for a second message that carries a BFR response;

encode an identifier of the UE in a third message for transmission to the access node; and

monitor communications from the access node for a fourth message that carries a collision handling response, and

the RF interface is to transmit the first message and the third message to the access node and receive the second message and the fourth message from the access node.
The apparatus of claim 1, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.
The apparatus of claim 2, wherein the CB-PRACH resource or the CB-PUCCH resource is dedicated to a BFR procedure at the UE.
The apparatus of claim 2, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a new candidate beam.
The apparatus of claim 2, wherein the CB-PRACH resource or the CB-PUCCH resource is associated with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) .
The apparatus of claim 2, wherein:

the first message and the third message are combined in a same message for transmission to the access node over the CB-PRACH resource or the CB-PUCCH resource; and

the second message and the fourth message are received in a same message from the access node.
The apparatus of claim 1, wherein the identifier of the UE is a cell radio network temporary identifier (C-RNTI) of the UE.
The apparatus of any of claims 1-7, wherein the processing circuitry is further to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message or the third message.
The apparatus of claim 8, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.
An apparatus for an access node serving a user equipment (UE) in a secondary cell, comprising:

a radio frequency (RF) interface; and

processing circuitry coupled with the RF interface,

wherein the processing circuitry is to:

decode a first message carrying a beam failure recovery (BFR) request from the UE;

encode a BFR response in a second message for transmission to the UE;

decode a third message carrying an identifier of the UE; and

encode a collision handling response in a fourth message for transmission to the UE, and

the RF interface is to receive the first message and the third message from the UE and transmit the second message and the fourth message to the UE.
The apparatus of claim 10, wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.
The apparatus of claim 11, wherein:

the first message and the third message are received from the UE in a same message over the CB-PRACH resource or the CB-PUCCH resource; and

the second message and the fourth message are combined in a same message for transmission to the UE.
The apparatus of claim 10, wherein:

a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the first message, and the processing circuitry is further to encode a confirmation with the new candidate beam in the second message; or

a failed Component Carrier (CC) index or information associated with a new candidate beam is carried in the third message, and the processing circuitry is further to encode a confirmation with the new candidate beam in the fourth message.
The apparatus of claim 13, wherein the information associated with the new candidate beam comprises a synchronization signal block (SSB) /channel state information reference signal (CSI-RS) resource index, a beam index or a quality indicator of the new candidate beam.
The apparatus of claim 11, wherein the second message is to be transmitted over a physical downlink control channel (PDCCH) in K slots after receiving the first message from the UE, where K is predefined or configured by higher-layer signaling.
The apparatus of claim 15, wherein the PDCCH is to be transmitted in a dedicated search space for beam failure recovery (SS-BFR) configured by higher-layer signaling, and the SS-BFR is associated with the CB-PRACH resource or the CB-PUCCH resource.
The apparatus of claim 16, wherein the SS-BFR is Quasi-Co-Located (QCLed) with a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) associated with the CB-PRACH resource or the CB-PUCCH resource.
The apparatus of claim 15, wherein the PDCCH is based on a DCI format scrambled by a cell radio network temporary identifier (C-RNTI) of the UE when the C-RNTI of the UE is carried in the first message over the CB-PRACH resource or the CB-PUCCH resource.
The apparatus of claim 15, wherein the PDCCH is based on a DCI format scrambled by a random access radio network temporary identifier (RA-RNTI) of the UE when the first message is to be transmitted over the CB-PRACH resource.
A computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of a user equipment (UE) operating in a secondary cell (SCell) , to cause the one or more processors to:

determine a beam failure occurs in the secondary cell;

encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE;

monitor communications from the access node for a second message that carries a BFR response;

encode an identifier of the UE in a third message for transmission to the access node; and

monitor communications from the access node for a fourth message that carries a collision handling response,

wherein the first message is to be transmitted to the access node over a contention based physical random access channel (CB-PRACH) resource or a contention based physical uplink control channel (CB-PUCCH) resource configured by higher-layer signaling.
The computer-readable medium of claim 20, wherein:

the first message and the third message are combined in a same message for transmission to the access node over the CB-PRACH resource or the CB-PUCCH resource; and

the second message and the fourth message are received in a same message from the access node.
The computer-readable medium of claim 20, wherein the instructions, when executed by the one or more processors of the UE, further cause the one or more processors to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in the first message or the third message.
A computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors of a user equipment (UE) operating in a secondary cell (SCell) , to cause the one or more processors to:

determine a beam failure occurs in the secondary cell;

encode a beam failure recovery (BFR) request in a first message for transmission to an access node serving the UE; and

monitor communications from the access node for a second message that carries a BFR response,

wherein the first message is to be transmitted to the access node over a contention free physical random access channel (CF-PRACH) resource or a contention free physical uplink control channel (CF-PUCCH) resource configured by higher-layer signaling.
The computer-readable medium of claim 23, wherein the instructions, when executed by the one or more processors of the UE, further cause the one or more processors to encode a failed Component Carrier (CC) index or information associated with a new candidate beam in a third message for transmission to the access node.
The computer-readable medium of claim 24, wherein the third message is to be transmitted over a physical uplink shared channel (PUSCH) in response to an uplink grant from the access node.