# US 10,484,076 B2 · Methods, network node and wireless terminal for beam tracking when beamforming is employed > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,484,076 B2 - Document ID: US10484076B2 - Status: Granted - Kind: B2 - Application number: 15/759,876 - Filed: 2018-02-06 - Published: 2019-02-14 - Granted: 2019-11-19 - Earliest claimed: 2017-03-22 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Johan Furuskog; Håkan Andersson; Mattias Frenne; Johan Kåredal; John Skördeman; Tomas Sundin; Niclas Wiberg; Qiang Zhang - Web page: https://patentgrep.com/patent/US10484076B2 ## CPC - H04B 7/088: {using beam selection} - H04B 7/0617: {for beam forming} - H04B 7/06952: {Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping} - H04B 17/328: {Reference signal received power [RSRP]; Reference signal received quality [RSRQ]} - H04W 16/28: using beam steering - 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 A network node (100), a wireless terminal (102) and methods therein, for supporting beam tracking in the wireless terminal (102) when a selected network beam (Bc) and a selected terminal beam (Tc) are used. The network node (100) identifies a set of candidate network beams (B) having spatial characteristics similar to the selected network beam (Bc), and signals the candidate network beams to the wireless terminal (102). When the network node (100) transmits beam reference signals in the candidate network beams using beam sweeping, the wireless terminal (102) measures received power using different candidate terminal beams (T) and estimates received power of combinations of beam reference signal and candidate terminal beam that have not been measured, based on the measured combinations of beam reference signal and candidate terminal beam. ## Claims ### Claim 1 A method performed by a network node for supporting beam tracking in a wireless terminal when beamforming is employed in radio communication between the wireless terminal and the network node using a current selected network beam (Bc) and a current selected terminal beam (Tc), the method comprising: identifying a set of candidate network beams (B) having spatial characteristics similar to the current selected network beam (Bc), wherein a beam reference signal is associated with each candidate network beam in the set of candidate network beams (B); signalling to the wireless terminal identities of the beam reference signals associated with the set of candidate network beams (B) or identities of the candidate network beams; and transmitting the beam reference signals in the set of candidate network beams (B) using beam sweeping where at least some of the beam reference signals are transmitted separately multiple times, thereby enabling the wireless terminal to measure received power of the beam reference signals using different candidate terminal beams (T). ### Claim 2 (depends on 1) A method according to claim 1, wherein the set of candidate network beams (B) is identified as transmitted from the same transmission point as the selected network beam (Bc). ### Claim 3 (depends on 1) A method according to claim 1, wherein the set of candidate network beams (B) is identified as being sufficiently strong for reception by the wireless terminal. ### Claim 4 (depends on 1) A method according to claim 1, wherein the set of candidate network beams (B) is identified as transmitted in similar directions as the selected network beam (Bc). ### Claim 5 (depends on 1) A method according to claim 1, wherein the set of candidate network beams (B) is identified by using a machine-learning algorithm to determine groups of network beams that generally have the same best terminal beam. ### Claim 6 A network node arranged to support beam tracking in a wireless terminal when beamforming is employed in radio communication between the wireless terminal and the network node using a current selected network beam (Bc) and a current selected terminal beam (Tc), wherein the network node comprises: a communication circuit; at least one processor operatively coupled to the communication circuit; and at least one memory storing computer-executable instructions that, when executed by the at least one processor, configure the network node to: identify a set of candidate network beams (B) having spatial characteristics similar to the current selected network beam (Bc), wherein a beam reference signal is associated with each candidate network beam in the set of candidate network beams (B); signal to the wireless terminal identities of the beam reference signals associated with the set of candidate network beams (B) or identities of the candidate network beams; and transmit the beam reference signals in the set of candidate network beams (B) using beam sweeping where at least some of the beam reference signals are transmitted separately multiple times, thereby enabling the wireless terminal to measure received power of the beam reference signals using different candidate terminal beams (T). ### Claim 7 (depends on 6) A network node according to claim 6, wherein execution of the instructions further configures the network node to identify the set of candidate network beams (B) as transmitted from the same transmission point as the selected network beam (Bc). ### Claim 8 (depends on 6) A network node according to claim 6, wherein execution of the instructions further configures the network node to identify the set of candidate network beams (B) as being sufficiently strong for reception by the wireless terminal. ### Claim 9 (depends on 6) A network node according to claim 6, wherein execution of the instructions further configures the network node to identify the set of candidate network beams (B) as transmitted in similar directions as the selected network beam (Bc). ### Claim 10 (depends on 6) A network node according to claim 6, wherein execution of the instructions further configures the network node to identify the set of candidate network beams (B) by using a machine-learning algorithm to determine groups of network beams that generally have the same best terminal beam. ### Claim 11 A method performed by a wireless terminal for beam tracking when beamforming is employed in radio communication between the wireless terminal and a network node using a current selected network beam (Bc) and a current selected terminal beam (Tc), the method comprising: receiving from the network node identities of beam reference signals associated with a set of candidate network beams (B) or identities of the candidate network beams; measuring received power of said beam reference signals using different candidate terminal beams (T); and estimating received power of combinations of beam reference signal and candidate terminal beam (T) that have not been measured, based on the measured combinations of beam reference signal and candidate terminal beam (T). ### Claim 12 (depends on 11) A method according to claim 11, wherein measuring received power comprises: measuring each beam reference signal for the current selected terminal beam (Tc); and measuring at least one beam reference signal associated with a candidate network beam (B) for each candidate terminal beam in the set of candidate terminal beams (T). ### Claim 13 (depends on 12) A method according to claim 12, wherein estimating received power of combinations comprises estimating received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), by using a measured received power RP(Bc,T) of a second beam reference signal (Bc) in the first candidate terminal beam (T) and applying an offset based on a relation between a measured received power RP(B,To) of the first beam reference signal (B) in a second candidate terminal beam (To), and a measured received power RP(Bc,To) of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 14 (depends on 13) A method according to claim 13, wherein said relation is the difference between the measured received powers RP(B,To), RP(Bc,To) in decibels, or said relation is the ratio between the measured received powers RP(B,To), RP(Bc,To) in linear. ### Claim 15 (depends on 12) A method according to claim 12, estimating received power of combinations comprises estimating received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), by using a measured received power RP(B,To) of the first beam reference signal (B) in a second candidate terminal beam (To), and applying an offset based on a relation between a measured received power RP(Bc,T) of a second beam reference signal (Bc) in the first candidate terminal beam (T), and a measured received power RP(Bc,To) of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 16 (depends on 15) A method according to claim 15, wherein said relation is the difference between the measured received powers RP(Bc,T), RP(Bc,To) in decibels, or said relation is the ratio between the measured received powers RP(Bc,T), RP(Bc,To) in linear. ### Claim 17 (depends on 12) A method according to claim 12, wherein estimating received power of combinations comprises estimating received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), as RP(B,T) =RP(Bc,T) +RP(B,To) −RP(Bc,To), where: RP(Bc,T) is a measured received power of a second beam reference signal (Bc) in the first candidate terminal beam (T); RP(B,To) is a measured received power of the first beam reference signal (B) in a second candidate terminal beam (To); and RP(Bc,To) is a measured received power of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 18 (depends on 11) A method according to claim 11, further comprising selecting a new combination of network beam (B) and terminal beam (T) for use in the radio communication or for further evaluation, the new combination corresponding to a combination of beam reference signal and candidate terminal beam (T) that has a measured or estimated received power that is higher than the currently used combination of network beam (Bc) and terminal beam (Tc). ### Claim 19 A wireless terminal arranged to perform beam tracking when beamforming is employed in radio communication between the wireless terminal and a network node using a current selected network beam (Bc) and a current selected terminal beam (Tc), wherein the wireless terminal comprises: a communication circuit; at least one processor operatively coupled to the communication circuit; and at least one memory storing computer-executable instructions that, when executed by the at least one processor, configure the wireless terminal to: receive from the network node identities of beam reference signals associated with a set of candidate network beams (B) or identities of the candidate network beams; measure received power of said beam reference signals using different candidate terminal beams (T); and estimate received power of combinations of beam reference signal and candidate terminal beam (T) that have not been measured, based on the measured combinations of beam reference signal and candidate terminal beam (T). ### Claim 20 (depends on 19) A wireless terminal according to claim 19, wherein execution of the instructions further configures the wireless terminal to: measure each beam reference signal for the current selected terminal beam (Tc); and measure at least one beam reference signal associated with a candidate network beam (B) for each candidate terminal beam in the set of candidate terminal beams (T). ### Claim 21 (depends on 20) A wireless terminal according to claim 20, wherein execution of the instructions further configures the wireless terminal to estimate received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), by using a measured received power RP(Bc,T) of a second beam reference signal (Bc) in the first candidate terminal beam (T) and by applying an offset based on a relation between a measured received power RP(B,To) of the first beam reference signal (B) in a second candidate terminal beam (To) and a measured received power RP(Bc,To) of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 22 (depends on 21) A wireless terminal according to claim 21, wherein said relation is the difference between the measured received powers RP(B,To), RP(Bc,To) in decibels, or said relation is the ratio between the measured received powers RP(B,To), RP(Bc,To) in linear. ### Claim 23 (depends on 20) A wireless terminal according to claim 20, wherein execution of the instructions further configures the wireless terminal to estimate received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), by using a measured received power RP(B,To) of the first beam reference signal (B) in a second candidate terminal beam (To), and by applying an offset based on a relation between a measured received power RP(Bc,T) of a second beam reference signal (Bc) in the first candidate terminal beam (T) and a measured received power RP(Bc,To) of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 24 (depends on 23) A wireless terminal according to claim 23, wherein said relation is the difference between the measured received powers RP(Bc,T), RP(Bc,To) in decibels, or said relation is the ratio between the measured received powers RP(Bc,T), RP(Bc,To) in linear. ### Claim 25 (depends on 20) A wireless terminal according to claim 20, wherein execution of the instructions further configures the wireless terminal to estimate received power RP(B,T) of a non-measured combination of a first beam reference signal (B) and a first candidate terminal beam (T), as RP(B,T) =RP(Bc,T) +RP(B,To) −RP(Bc,To), where: RP(Bc,T) is a measured received power of a second beam reference signal (Bc) in the first candidate terminal beam (T), RP(B,To) is a measured received power of the first beam reference signal (B) in a second candidate terminal beam (To), and RP(Bc,To) is a measured received power of the second beam reference signal (Bc) in the second candidate terminal beam (To). ### Claim 26 (depends on 19) A wireless terminal according to claim 19, wherein execution of the instructions further configures the wireless terminal to select a new combination of network beam (B) and terminal beam (T) for use in the radio communication or for further evaluation, corresponding to a combination of beam reference signal and candidate terminal beam (T) that has a measured or estimated received power that is higher than the currently used combination of network beam (Bc) and terminal beam (Tc). ### Claim 27 (depends on 1) A non-transitory, computer-readable medium comprising computer-executable instructions that, when executed on at least one processor comprising a network node, cause the network node to carry out operations corresponding to the method of claim 1. ### Claim 28 (depends on 11) A non-transitory, computer-readable medium comprising computer-executable instructions that, when executed on at least one processor comprising a wireless terminal, cause the wireless terminal to carry out operations corresponding to the method of claim 11.