# US 11,309,941 B2 · System and method for beam switching and reporting > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,309,941 B2 - Document ID: US11309941B2 - Status: Granted - Kind: B2 - Application number: 16/794,120 - Filed: 2020-02-18 - Published: 2020-06-11 - Granted: 2022-04-19 - Earliest claimed: 2016-05-26 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Muhammad Nazmul Islam; Bilal Sadiq; Tao Luo; Sundar Subramanian; Junyi Li - Web page: https://patentgrep.com/patent/US11309941B2 ## CPC - H04B 7/0417: Feedback systems - H01Q 1/245: {with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure} - H04B 7/0404: the mobile station comprising multiple antennas, e.g. to provide uplink diversity - H04B 7/0426: Power distribution - H04B 7/0452: Multi-user MIMO systems - H04B 7/061: {using feedback from receiving side} - H04B 7/0617: {for beam forming} - H04B 7/0621: {Feedback content} - H04B 7/088: {using beam selection} - H04W 16/28: using beam steering - H04W 28/0221: {power availability or consumption} - H04W 40/08: based on transmission power - H04W 52/146: {Uplink power control} - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 74/0838: using contention-free random access [CFRA] - H04B: TRANSMISSION - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A UE may select a first beam for communication with a base station. The UE may attempt, through the selected first beam, at least one RACH procedure with the base station. The UE may determine that the at least one RACH procedure failed with the base station. The UE may send, after a successful RACH procedure with the base station, information indicating that the at least one RACH procedure failed. In an aspect, the UE may select a new beam for communication with the base station after the determination that the at least one RACH procedure failed, and at least a portion of the successful RACH procedure may be performed through the selected new beam. ## Claims ### Claim 1 A method of wireless communication by a user equipment (UE), comprising: determining that communication with a base station is unsuccessful; initiating a non-contention-based random access channel (RACH) procedure with the base station using a first beam when the communication with the base station is unsuccessful; determining that the non-contention-based RACH procedure with the base station is unsuccessful; initiating a contention-based RACH procedure with the base station using a second beam based on determining that the non-contention-based RACH procedure is unsuccessful; and sending information indicating an index corresponding to the first beam through which the non-contention-based RACH procedure was unsuccessful. ### Claim 2 (depends on 1) The method of claim 1, further comprising: selecting the first beam from a list of candidate beams associated with the communication with the base station when the communication with the base station is unsuccessful; and selecting the second beam from the list of candidate beams when the non-contention-based RACH procedure using the first beam is unsuccessful. ### Claim 3 (depends on 2) The method of claim 2, further comprising: determining the list of candidate beams associated with the communication with the base station before the communication with the base station is unsuccessful. ### Claim 4 (depends on 2) The method of claim 2, further comprising: excluding the first beam from the list of candidate beams when the second beam is selected. ### Claim 5 (depends on 1) The method of claim 1, wherein the determining that the non-contention-based RACH procedure is unsuccessful is based on expiration of a timer. ### Claim 6 (depends on 1) The method of claim 1, wherein the non-contention-based RACH procedure is initiated on at least one resource associated with the non-contention-based RACH procedure. ### Claim 7 (depends on 1) The method of claim 1, further comprising: determining that a quality of a third beam used for the communication with the base station is deteriorated, wherein the determining that the communication with the base station is unsuccessful is based on the determining that the quality of the third beam is deteriorated. ### Claim 8 An apparatus for wireless communication by a user equipment (UE), comprising: means for determining that communication with a base station is unsuccessful; means for initiating a non-contention-based random access channel (RACH) procedure with the base station using a first beam when the communication with the base station is unsuccessful; means for determining that the non-contention-based RACH procedure with the base station is unsuccessful; means for initiating a contention-based RACH procedure with the base station using a second beam based on the determining that the non-contention-based RACH procedure is unsuccessful; and means for sending information indicating an index corresponding to the first beam through which the non-contention-based RACH procedure was unsuccessful. ### Claim 9 (depends on 8) The apparatus of claim 8, further comprising: means for selecting the first beam from a list of candidate beams associated with the communication with the base station when the communication with the base station is unsuccessful; and means for selecting the second beam from the list of candidate beams when the non-contention-based RACH procedure using the first beam is unsuccessful. ### Claim 10 (depends on 9) The apparatus of claim 9, further comprising: means for determining the list of candidate beams associated with the communication with the base station before the communication with the base station is unsuccessful. ### Claim 11 (depends on 9) The apparatus of claim 9, further comprising: means for excluding the first beam from the list of candidate beams when the second beam is selected. ### Claim 12 (depends on 8) The apparatus of claim 8, wherein the determining that the non-contention-based RACH procedure is unsuccessful is based on expiration of a timer. ### Claim 13 (depends on 8) The apparatus of claim 8, wherein the non-contention-based RACH procedure is initiated on at least one resource associated with the non-contention-based RACH procedure. ### Claim 14 (depends on 8) The apparatus of claim 8, further comprising: means for determining that a quality of a third beam used for the communication with the base station is deteriorated, wherein the means for determining that the communication with the base station is unsuccessful is configured for the determining based on determining that the quality of the third beam is deteriorated. ### Claim 15 An apparatus for wireless communication by a user equipment (UE), comprising: a memory; and at least one processor coupled to the memory and configured to: determine that communication with a base station is unsuccessful; initiate a non-contention-based random access channel (RACH) procedure with the base station using a first beam when the communication with the base station is unsuccessful; determining that the non-contention-based RACH procedure with the base station is unsuccessful; initiate a contention-based RACH procedure with the base station using a second beam based on determining that the non-contention-based RACH procedure is unsuccessful; and send information indicating an index corresponding to the first beam through which the non-contention-based RACH procedure was unsuccessful. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the at least one processor is further configured to: select the first beam from a list of candidate beams associated with the communication with the base station when the communication with the base station is unsuccessful; and select the second beam from the list of candidate beams when the non-contention-based RACH procedure using the first beam is unsuccessful. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the at least one processor is further configured to: determine the list of candidate beams associated with the communication with the base station before the communication with the base station is unsuccessful. ### Claim 18 (depends on 16) The apparatus of claim 16, wherein the at least one processor is further configured to: excluding the first beam from the list of candidate beams when the second beam is selected. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the determining that the first type of RACH procedure is unsuccessful is based on expiration of a timer. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein the non-contention-based RACH procedure is initiated on at least one resource associated with the first type of RACH procedure. ### Claim 21 (depends on 15) The apparatus of claim 15, wherein the at least one processor is further configured to: determine that a quality of a third beam used for the communication with the base station is deteriorated, wherein the determination that the communication with the base station is unsuccessful is based on the determination that the quality of the third beam is deteriorated. ### Claim 22 A non-transitory computer-readable medium storing computer-executable code for wireless communication by a user equipment (UE), the code when executed by a processor cause the processor to: determine that communication with a base station is unsuccessful; initiate a non-contention-based random access channel (RACH) procedure with the base station using a first beam when the communication with the base station is unsuccessful; determine that the non-contention-based RACH procedure with the base station is unsuccessful; initiate a contention-based RACH procedure with the base station using a second beam based on the determining that the non-contention-based RACH procedure is unsuccessful; and send information indicating an index corresponding to the first beam through which the non-contention-based RACH procedure was unsuccessful.