# US 11,909,487 B2 · Beamforming for random access channel (RACH) > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,487 B2 - Document ID: US11909487B2 - Status: Granted - Kind: B2 - Application number: 17/267,355 - Filed: 2018-08-10 - Published: 2021-08-26 - Granted: 2024-02-20 - Earliest claimed: 2018-08-10 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (PUBL) - Inventors: Henrik Asplund; Arne Simonsson; David Astely - Web page: https://patentgrep.com/patent/US11909487B2 ## CPC - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04B 7/088: {using beam selection} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION ## Abstract The present disclosure relates to a method performed by a network node for beamforming, to a network node and to a system including a network node. One aspect of the disclosure provides a method (900) comprising: obtaining (910), at the network node (800), information relating to a plurality of signals received or transmitted using a set of receiving beams or a set of transmitting beams of the network node (800), each individual beam of the set having a unique beam direction; determining a set of candidate beams for use by the network node (800) for synchronisation signal, SS, transmission or random access channel, RACH, detection; based on the obtained information, selecting one or more of the determined candidate beams; and using the selected one or more of the determined candidate beams for SS transmission or RACH detection by the network node (800). ## Claims ### Claim 1 A method performed by a network node for beamforming, the method comprising: obtaining, at the network node, information relating to a plurality of signals received or transmitted using a set of receiving beams or a set of transmitting beams of the network node, wherein the information relates to one or more of: path loss between a receiving device and the network node; signal strength of a signal of the plurality of signals transmitted by the network node; and a random access success ratio for a beam of the set of beams used by the network node to transmit the plurality of signals and the information is derived from multiple measurements performed over a period of time; and each individual beam of the set having a unique beam direction; determining a set of candidate beams for use by the network node for synchronization signal, SS, transmission or random access channel, RACH detection; based on the obtained information, selecting one or more of the determined candidate beams, wherein selecting one or more of the candidate beams comprises selecting a first subset of the set of candidate beams and selecting a second subset of the set of candidate beams, and wherein using the selected one or more of the determined candidate beams for SS transmission or RACH detection by the network node comprises using the selected first subset for individual narrow-beam SS transmission or RACH detection and using the selected second subset for broad-beam SS transmission or RACH detection; and using the selected one or more of the determined candidate beams for SS transmission or RACH detection by the network node. ### Claim 2 (depends on 1) The method according to claim 1 wherein the plurality of signals received or transmitted using a set of receiving beams or a set of transmitting beams of the network node comprise: synchronization signal blocks; or RACH signals; or reference signals. ### Claim 3 (depends on 1) The method according to claim 1 wherein the information comprises a function of direction of arrival, DoA, of each individual beam. ### Claim 4 (depends on 3) The method according to claim 3, wherein the DoA is defined at least in part by an angle of elevation and an azimuth angle. ### Claim 5 (depends on 1) The method according to claim 1, wherein obtaining the information comprises: transmitting by the network node, using some or all of the individual beams of the set of transmitting beams, a plurality of signals; and/or, receiving, at the network node, signals from one or more receiving devices; and, deriving the information from the received signals or from information derived from the received signals. ### Claim 6 (depends on 1) The method according to claim 1 wherein the signals received at the network node are response signals received from the one or more receiving devices in response to the transmitted plurality of signals. ### Claim 7 (depends on 1) The method according to claim 1 wherein the first subset comprises a predetermined number of the candidate beams which are associated in the information with a lowest signal strength or a highest path loss. ### Claim 8 (depends on 1) The method according to claim 1 wherein the set of beams comprises a grid of beams. ### Claim 9 A network node comprising: a radio interface comprising a beamforming antenna; a processor; and memory, wherein the memory stores instructions which, when executed by the processor, cause the network node to: obtain information relating to a plurality of signals received or transmitted using a set of receiving beams or a set of transmitting beams of the network node, wherein the information relates to one or more of: path loss between a receiving device and the network node; signal strength of a signal of the plurality of signals transmitted by the network node; and a random access success ratio for a beam of the set of beams used by the network node to transmit the plurality of signals; and the information is derived from multiple measurements performed over a period of time and each individual beam of the set of transmitting beams having a unique beam direction; determine a set of candidate beams for use by the network node for synchronisation signal, SS, transmission or random access channel, RACH, detection; based on the obtained information, select one or more of the determined candidate beams, wherein selecting the one or more of the candidate beams comprises: selecting a first subset of the set of candidate beams and selecting a second subset of the set of candidate beams, and further cause the network node to use the selected first subset for individual narrow-beam SS transmission or RACH detection and to use the selected second subset for broad-beam SS transmission or RACH detection; and use the one or more determined candidate beams for SS transmission or RACH detection by the network node. ### Claim 10 (depends on 9) The network node according to claim 9 wherein the plurality of signals received or transmitted using a set of receiving beams or a set of transmitting beams of the network node comprise: synchronization signal blocks; or RACH signals; or reference signals. ### Claim 11 (depends on 9) The network node according to claim 9 wherein the information comprises a function of direction of arrival, DoA, of each individual beam. ### Claim 12 (depends on 11) The network node according to claim 11, wherein the DoA is defined at least in part by an angle of elevation and an azimuth angle. ### Claim 13 (depends on 9) The network node according to claim 9 wherein the instructions which, when executed by the processor, cause the network node to obtain the information comprise instructions which, when executed by the processor, cause the network node to: transmit, using some or all of the individual beams of the set of transmitting beams, a plurality of signals; and/or, receive signals from one or more receiving devices; and derive the information from the received signals or from information derived from the received signals. ### Claim 14 (depends on 13) The network node according to claim 13 wherein the signals received at the network node are response signals received from the one or more receiving devices in response to the transmitted plurality of signals. ### Claim 15 (depends on 9) The network node according to claim 9, wherein the first subset comprises a predetermined number of the candidate beams which are associated in the information with a lowest signal strength or a highest path loss. ### Claim 16 (depends on 9) The network node according to claim 9 wherein the set of beams comprises a grid of beams. ### Claim 17 A system comprising: a network node; and one or more wireless devices, wherein the network node is configured to: transmit a plurality of signals into a coverage area of the network node using a set of transmitting beams of the network node, each individual beam of the set having a unique beam direction; receive one or more signals from the one or more wireless devices using a set of receiving beams of the network node, each individual beam of the set having a unique beam direction, wherein the system is configured to: obtain information relating to the signals received or transmitted using the set of receiving beams or the set of transmitting beams of the network node wherein the information relates to one or more of: path loss between a receiving device and the network node; signal strength of a signal of the plurality of signals transmitted by the network node; and a random access success ratio for a beam of the set of beams used by the network node to transmit the plurality of signals; and the information is derived from multiple measurements performed over a period of time and; determine a set of candidate beams for use by the network node for synchronization signal, SS, transmission or random access channel, RACH, detection; based on the obtained information, select one or more of the determined candidate beams, and wherein the network node is further configured to: use the selected one or more of the determined candidate beams for SS transmission or RACH detection by the network node, wherein selecting the one or more of the candidate beams comprises: selecting a first subset of the set of candidate beams and selecting a second subset of the set of candidate beams, and further cause the network node to use the selected first subset for individual narrow-beam SS transmission or RACH detection and to use the selected second subset for broad-beam SS transmission or RACH detection. ### Claim 18 (depends on 17) The system according to claim 17, wherein the system further comprises: a data processing entity, wherein the data processing entity is configured to: receive, from the network node, information relating to the signals received or transmitted using the set of receiving beams or the set of transmitting beams of the network node; process the information received from the network node to derive the information; and transmit the derived information to the network node, and wherein the network node is configured to: determine the set of candidate beams for use by the network node for SS transmission or RACH detection; and based on the obtained information, select one or more of the determined candidate beams. ### Claim 19 (depends on 17) The system according to claim 17, wherein the system further comprises: a data processing entity, wherein the data processing entity is configured to: receive, from the network node, information relating to the signals received or transmitted using the set of receiving beams or the set of transmitting beams of the network node; process the information received from the network node to derive the information; determine the set of candidate beams for use by the network node for SS transmission or (RACH detection; based on the obtained information, select one or more of the determined candidate beams; and transmit information defining the selected one or more of the determined candidate beams to the network node. ### Claim 20 (depends on 18) The system according to claim 18, wherein the signals received or transmitted using the set of receiving beams or a set of transmitting beams of the network node comprise: synchronization signal blocks; or (RACH signals; or reference signals.