# US 12,603,692 B2 · Methods and apparatus for beam determination for physical uplink control channel (PUCCH) transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,603,692 B2 - Document ID: US12603692B2 - Status: Granted - Kind: B2 - Application number: 18/146,971 - Filed: 2022-12-27 - Published: 2023-05-04 - Granted: 2026-04-14 - Earliest claimed: 2020-11-02 - Assignees: Guangdong Oppo Mobile Telecommunications Corp., Ltd. - Applicants: Guangdong Oppo Mobile Telecommunications Corp., Ltd. - Inventors: Li Guo - Web page: https://patentgrep.com/patent/US12603692B2 ## CPC - H04B 7/06964: {Re-selection of one or more beams after beam failure} - H04W 52/325: {Power control of control or pilot channels} - H04W 72/20: Control channels or signalling for resource management - H04W 72/231: the control data signalling from the layers above the physical layer, e.g. RRC or MAC-CE signalling - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 74/0836: with 2-step access - H04W 76/15: Setup of multiple wireless link connections - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Methods and systems for starting a contention-based random-access channel (RACH) upon detecting beam failure of a serving cell. The method includes transmitting a medium access control (MAC) control element (CE), signaling the beam failure of the serving cell in a message of the contention-based RACH. The method further includes determining completion of the contention-based RACH based on receipt of a physical downlink control channel (PDCCH); and after receiving one or more of the last symbols of the PDCCH, determining a default transmission (Tx) beam for each resource of a physical uplink control channel (PUCCH) that includes a PUCCH spatial relation information parameter. ## Claims ### Claim 1 A method, executable by a user equipment (UE), the method comprising: upon detecting beam failure of a serving cell, starting a contention-based random-access channel (RACH); transmitting a medium access control (MAC) control element (CE), wherein the MAC CE signals the beam failure of the serving cell in a message of the contention-based RACH; determining completion of the contention-based RACH based on receipt of a physical downlink control channel (PDCCH); determining whether each resource of a physical uplink control channel (PUCCH) is configured with a PUCCH spatial relation information parameter, and when determining that the resource of the PUCCH is configured with the PUCCH spatial relation information parameter, after receiving one or more of the last symbols of the PDCCH, determining a default transmission (Tx) beam for the resource of the PUCCH that includes the PUCCH spatial relation information parameter. ### Claim 2 (depends on 1) The method of claim 1, wherein the default Tx beam matches a spatial-domain filter used in the latest physical RACH (PRACH) transmission. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining, after receiving one or more of the last symbols of the PDCCH, one or more power control parameters. ### Claim 4 (depends on 3) The method of claim 3, wherein the power control parameters comprise a reference signal (RS) resource index for uplink, qu, an RS resource index for downlink, qd, and/or a PUCCH power control adjustment state, I. ### Claim 5 (depends on 4) The method of claim 4, further comprising setting qu to 0. ### Claim 6 (depends on 4) The method of claim 4, further comprising setting qd to a RS selected for a preamble (Msg1) Tx in the PRACH, qnew. ### Claim 7 (depends on 4) The method of claim 4, further comprising setting I to 0. ### Claim 8 (depends on 1) The method of claim 1, further comprising: receiving, from a next-generation node B base station (gNB), one or more PUCCH resources, wherein one or more of the PUCCH resources includes the PUCCH spatial relation information parameter. ### Claim 9 (depends on 1) The method of claim 1, wherein the serving cell is either a primary cell (PCell) or a primary secondary cell (PSCell). ### Claim 10 (depends on 1) The method of claim 1, wherein the message of the contention-based RACH is a scheduled physical uplink shared channel (PUSCH) Tx (Msg3). ### Claim 11 (depends on 1) The method of claim 1, wherein the message of the contention-based RACH is a single message (MsgA), wherein MsgA comprises a preamble (Msg1) and a scheduled PUSCH Tx (Msg3). ### Claim 12 A user equipment (UE), comprising a processor and a memory, wherein the processor is configured to cause the UE to: start a contention-based random-access channel (RACH) upon detecting beam failure of a serving cell; transmit a medium access control (MAC) control element (CE), wherein the MAC CE signals the beam failure of the serving cell in a message of the contention-based RACH; determine completion of the contention-based RACH based on receipt of a physical downlink control channel (PDCCH); determine whether each resource of a physical uplink control channel (PUCCH) is configured with a PUCCH spatial relation information parameter, and when determining that the resource of the PUCCH is configured with the PUCCH spatial relation information parameter, after receiving one or more of the last symbols of the PDCCH, determine a default Tx beam for the resource of the PUCCH that includes the PUCCH spatial relation information parameter. ### Claim 13 (depends on 12) The UE of claim 12, wherein the default Tx beam matches a spatial-domain filter used in the latest physical RACH (PRACH) transmission. ### Claim 14 (depends on 12) The UE of claim 12, wherein the processor is further configured to cause the UE to: determine, after receiving one or more of the last symbols of the PDCCH, one or more power control parameters. ### Claim 15 (depends on 14) The UE of claim 14, wherein the power control parameters comprise a reference signal (RS) resource index for uplink, qu, an RS resource index for downlink, qd, and/or a PUCCH power control adjustment state, I. ### Claim 16 (depends on 15) The UE of claim 15, wherein the processor is further configured to cause the UE to set qu to 0. ### Claim 17 (depends on 15) The UE of claim 15, wherein the processor is further configured to cause the UE to set qd to a RS selected for a preamble (Msg1) Tx in the PRACH, qnew. ### Claim 18 (depends on 15) The UE of claim 15, wherein the processor is further configured to cause the UE to set I to 0. ### Claim 19 (depends on 12) The UE of claim 12, wherein the processor is further configured to cause the UE to: receive, from a next-generation node B base station (gNB), one or more PUCCH resources, wherein one or more of the PUCCH resources includes the PUCCH spatial relation information parameter. ### Claim 20 (depends on 12) The UE of claim 12, wherein the serving cell is either a primary cell (PCell) or a primary secondary cell (PSCell), wherein the message of the contention-based RACH is a scheduled physical uplink shared channel (PUSCH) Tx (Msg3); or the message of the contention-based RACH is a single message (MsgA), wherein MsgA comprises a preamble (Msg1) and a scheduled PUSCH Tx (Msg3).