# US 2021/0242924 A1 · Beam training performed by a terminal device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242924 A1 - Document ID: US20210242924A1 - Status: Published application - Kind: A1 - Application number: 17/236,437 - Filed: 2021-04-21 - Published: 2021-08-05 - Earliest claimed: 2019-05-15 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Andreas NILSSON - Web page: https://patentgrep.com/patent/US20210242924A1 ## CPC - H04B 7/06952: {Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping} - H04B: TRANSMISSION ## Abstract A mechanisms for beam training. The method includes receiving, using a fixed beam, a first occurrence of a set of beam reference signals. The method includes determining a respective compensation factor for at least one of the received beam reference signals. The method includes receiving, using a set of directional beams, a second occurrence of the set of beam reference signals. The method includes evaluating which directional beam in the set of directional beams to use for subsequent communication with the network node based on strongest received beam reference signal in the second occurrence of the set of beam reference signals as compensated for using the compensation factors. ## Claims ### Claim 1 A method for beam training, the method being performed by a terminal device, the method comprising: the terminal device using a first receive beam (RXB1) to receive a first beam reference signal transmitted by a base station using a first transmit (TX) beam; the terminal device obtaining a first measurement value related to a measurement of the received first beam reference signal; the terminal device using the RXB1 to receive a second beam reference signal transmitted by the base station using a second TX beam; the terminal device obtaining a second measurement value related to a measurement of the received second beam reference signal; the terminal device using the first and second measurement values to calculate a compensation value; the terminal device using a second receive beam (RXB2) to receive a third beam reference signal transmitted by the base station using the first TX beam; the terminal device obtaining a third measurement value related to a measurement of the received third beam reference signal; the terminal device using a third receive beam (RXB3) to receive a fourth beam reference signal transmitted by the base station using the second TX beam; the terminal device obtaining a fourth measurement value related to a measurement of the received fourth beam reference signal; the terminal device adjusting the third measurement value using the calculated compensation value, thereby obtaining a compensated third measurement value; and the terminal device using the compensated third measurement value and the fourth measurement value to select an RX beam from a set of RX beams comprising the second RX beam and the third RX beam. ### Claim 2 (depends on 1) The method of claim 1, wherein the first beam reference signal is a part of a Synchronization Signal Block (SSB) and the second beam reference signal is also part of the SSB. ### Claim 3 (depends on 2) The method of claim 2, wherein the SSB comprises a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS), the first beam reference signal is the PSS, and the second beam reference signal is the SSS. ### Claim 4 (depends on 2) The method of claim 2, wherein the SSB comprises a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and Demodulation Reference Signal (DMRS); the first beam reference signal is the PSS or the SSS, and the second beam reference signal is the DMRS. ### Claim 5 (depends on 1) The method of claim 1, wherein using the first measurement value (m1) and the second measurement value (m2) to calculate the compensation value (cv) comprises: i) calculating cv=m1−m2 or ii) calculating cv=m2−m1. ### Claim 6 (depends on 1) The method of claim 1, wherein adjusting the third measurement value (m3) using the calculated compensation value (cv), thereby obtaining a compensated third measurement value (m3′) comprises calculating: m3′=m3+cv. ### Claim 7 (depends on 1) The method of claim 1, wherein RXB1 is wider than RXB2 and RSB1 is also wider than RXB3. ### Claim 8 (depends on 7) The method of claim 7, wherein RXB1 is not a directional beam, RXB2 is a directional beam that points in a first direction, and RXB3 is a directional beam that points in a second direction that is different than the first direction. ### Claim 9 A terminal device for beam training, the terminal device comprising processing circuitry, the processing circuitry being configured to cause the terminal device to perform a process that includes: the terminal device using a first receive beam (RXB1) to receive a first beam reference signal transmitted by a base station using a first transmit (TX) beam; the terminal device obtaining a first measurement value related to a measurement of the received first beam reference signal; the terminal device using the RXB1 to receive a second beam reference signal transmitted by the base station using a second TX beam; the terminal device obtaining a second measurement value related to a measurement of the received second beam reference signal; the terminal device using the first and second measurement values to calculate a compensation value; the terminal device using a second receive beam (RXB2) to receive a third beam reference signal transmitted by the base station using the first TX beam; the terminal device obtaining a third measurement value related to a measurement of the received third beam reference signal; the terminal device using a third receive beam (RXB3) to receive a fourth beam reference signal transmitted by the base station using the second TX beam; the terminal device obtaining a fourth measurement value related to a measurement of the received fourth beam reference signal; the terminal device adjusting the third measurement value using the calculated compensation value, thereby obtaining a compensated third measurement value; and the terminal device using the compensated third measurement value and the fourth measurement value to select an RX beam from a set of RX beams comprising the second RX beam and the third RX beam. ### Claim 10 (depends on 9) The terminal device of claim 9, wherein the first beam reference signal is a part of a Synchronization Signal Block (SSB) and the second beam reference signal is also part of the SSB. ### Claim 11 (depends on 10) The terminal device of claim 10, wherein the SSB comprises a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS), the first beam reference signal is the PSS, and the second beam reference signal is the SSS. ### Claim 12 (depends on 10) The terminal device of claim 10, wherein the SSB comprises a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and Demodulation Reference Signal (DMRS); the first beam reference signal is the PSS or the SSS, and the second beam reference signal is the DMRS. ### Claim 13 (depends on 9) The terminal device of claim 9, wherein using the first measurement value (m1) and the second measurement value (m2) to calculate the compensation value (cv) comprises: i) calculating cv=m1−m2 or ii) calculating cv=m2−m1. ### Claim 14 (depends on 9) The terminal device of claim 9, wherein adjusting the third measurement value (m3) using the calculated compensation value (cv), thereby obtaining a compensated third measurement value (m3′) comprises calculating: m3′=m3+cv. ### Claim 15 (depends on 9) The terminal device of claim 9, wherein RXB1 is wider than RXB2 and RSB1 is also wider than RXB3. ### Claim 16 (depends on 15) The terminal device of claim 15, wherein RXB1 is not a directional beam, RXB2 is a directional beam that points in a first direction, and RXB3 is a directional beam that points in a second direction that is different than the first direction. ### Claim 17 A computer program product comprising a non-transitory computer readable medium storing a computer program for beam training, the computer program comprising computer code which, when run on processing circuitry of a terminal device, causes the terminal device to perform a process that includes: the terminal device using a first receive beam (RXB1) to receive a first beam reference signal transmitted by a base station using a first transmit (TX) beam; the terminal device obtaining a first measurement value related to a measurement of the received first beam reference signal; the terminal device using the RXB1 to receive a second beam reference signal transmitted by the base station using a second TX beam; the terminal device obtaining a second measurement value related to a measurement of the received second beam reference signal; the terminal device using the first and second measurement values to calculate a compensation value; the terminal device using a second receive beam (RXB2) to receive a third beam reference signal transmitted by the base station using the first TX beam; the terminal device obtaining a third measurement value related to a measurement of the received third beam reference signal; the terminal device using a third receive beam (RXB3) to receive a fourth beam reference signal transmitted by the base station using the second TX beam; the terminal device obtaining a fourth measurement value related to a measurement of the received fourth beam reference signal; the terminal device adjusting the third measurement value using the calculated compensation value, thereby obtaining a compensated third measurement value; and the terminal device using the compensated third measurement value and the fourth measurement value to select an RX beam from a set of RX beams comprising the second RX beam and the third RX beam. ### Claim 18 (depends on 17) The computer program product of claim 17, wherein the first beam reference signal is a part of a Synchronization Signal Block (SSB) and the second beam reference signal is also part of the SSB. ### Claim 19 (depends on 18) The computer program product of claim 18, wherein the SSB comprises a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS), the first beam reference signal is the PSS, and the second beam reference signal is the SSS. ### Claim 20 (depends on 18) The computer program product of claim 18, wherein the SSB comprises a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and Demodulation Reference Signal (DMRS); the first beam reference signal is the PSS or the SSS, and the second beam reference signal is the DMRS. ### Claim 21 (depends on 17) The computer program product of claim 17, wherein using the first measurement value (m1) and the second measurement value (m2) to calculate the compensation value (cv) comprises: i) calculating cv=m1−m2 or ii) calculating cv=m2−m1. ### Claim 22 (depends on 17) The computer program product of claim 17, wherein adjusting the third measurement value (m3) using the calculated compensation value (cv), thereby obtaining a compensated third measurement value (m3′) comprises calculating: m3′=m3+cv. ### Claim 23 (depends on 17) The computer program product of claim 17, wherein RXB1 is wider than RXB2 and RSB1 is also wider than RXB3. ### Claim 24 (depends on 23) The computer program product of claim 23, wherein RXB1 is not a directional beam, RXB2 is a directional beam that points in a first direction, and RXB3 is a directional beam that points in a second direction that is different than the first direction.