# US 10,873,405 B2 · Method for obtaining uplink calibration values, calibration method, and corresponding terminal and base station > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,405 B2 - Document ID: US10873405B2 - Status: Granted - Kind: B2 - Application number: 16/251,739 - Filed: 2019-01-18 - Published: 2019-05-23 - Granted: 2020-12-22 - Earliest claimed: 2016-07-22 - Assignees: Huawei Technologies Duesseldorf GmbH - Applicants: Huawei Technologies Duesseldorf GmbH - Inventors: Samer Bazzi; Wen Xu - Web page: https://patentgrep.com/patent/US10873405B2 ## CPC - H04B 17/21: for calibration; for correcting measurements - H04B 7/0417: Feedback systems - H04B 7/061: {using feedback from receiving side} - H04B 7/0617: {for beam forming} - H04B 17/24: with feedback of measurements to the transmitter - H04B 17/327: Received signal code power [RSCP] - H04L 25/0202: {Channel estimation} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method for obtaining uplink calibration values in a terminal of a wireless communication system is provided, in order to enable a Base Station (BS) having a number of antennas to determine a respective hardware chain value for each antenna of the number of antennas, said method comprising calculating, by the terminal, an uplink calibration value for each antenna on the basis of a downlink channel estimate value for each antenna and a normalization value obtained from said downlink channel estimate values, and sending transmitting, by the terminal, the calculated uplink calibration value for each antenna to the BS. A corresponding terminal for a wireless communication system, adapted to obtain uplink calibration values, is also provided. ## Claims ### Claim 1 A method for obtaining uplink calibration values in a terminal of a wireless communication system to enable a Base Station (BS) having a number of antennas to determine a respective hardware chain value for each antenna of the number of antennas, the method comprising: obtaining, by the terminal, a downlink channel estimate value for each antenna, and determining a downlink channel estimate value with a lowest signal power, wherein the number of antennas are divided into groups; obtaining, by the terminal, a different normalization value for each group of antennas based on the downlink channel estimate value with the lowest signal power within each group; obtaining, by the terminal, an uplink calibration value for each antenna on the basis of the downlink channel estimate value for each antenna and the different normalization value for each group; transmitting, by the terminal, the obtained uplink calibration value for each antenna to the BS; and signaling, by the terminal, the obtained different normalization value for each group to the BS, wherein the BS further obtains the respective hardware chain value for each antenna from the received uplink calibration value and the obtained different normalization value. ### Claim 2 (depends on 1) The method according to claim 1, further comprising: receiving, by the terminal, a pilot signal on a downlink channel for each antenna from the BS, and obtaining, by the terminal, the downlink channel estimate value for each antenna from the received pilot signal. ### Claim 3 (depends on 1) The method according to claim 1, wherein the normalization value is calculated by the terminal as a function of maximum transmit power of the terminal and the downlink channel estimate value with the lowest signal power. ### Claim 4 (depends on 3) The method according to claim 3, further comprising: obtaining, by the terminal, the normalization value by multiplying the maximum transmit power of the terminal with a value obtained from the downlink channel estimate value with the lowest signal power. ### Claim 5 (depends on 4) The method according to claim 4, wherein the terminal obtains the value as the squared absolute value of the downlink channel estimate value with the lowest signal power. ### Claim 6 (depends on 1) The method according to claim 1, further comprising: obtaining, by the terminal, the uplink calibration values for each antenna by multiplying a normalization factor with the inverse of the respective downlink channel estimate value for each antenna, wherein the normalization factor is the square root of the normalization value. ### Claim 7 (depends on 1) The method according to claim 1, wherein the normalization value is the same normalization value for all antennas in the BS. ### Claim 8 (depends on 1) The method according to claim 1, wherein the number of antennas is grouped based on a maximum allowed signaling overhead or a number of free resources. ### Claim 9 A terminal for a wireless communication system, adapted to obtain uplink calibration values to enable a Base Station (BS), having a number of antennas to determine a respective hardware chain value for each antenna of the number of antennas, the terminal comprising: a processor, configured to: obtain, a downlink channel estimate value for each antenna, and determine a downlink channel estimate value with a lowest signal power, wherein the number of antennas are divided into groups; obtain a different normalization value for each group of antennas based on the downlink channel estimate value with the lowest signal power within each group; obtain an uplink calibration value for each antenna on the basis of the downlink channel estimate value for each antenna and the different normalization value for each group; a transmitter, configured to cooperate with the processor to transmit the obtained uplink calibration value for each antenna to the BS; and signal, the obtained different normalization value for each group to the BS, wherein the BS further obtains the respective hardware chain value for each antenna from the received uplink calibration value and the obtained different normalization value. ### Claim 10 (depends on 9) The terminal according to claim 9, wherein the terminal is a User equipment (UE) for the wireless communication system. ### Claim 11 (depends on 9) The terminal according to claim 9, wherein the terminal is either integrated into the BS or co-located with the BS and exclusively adapted to obtain the uplink calibration values. ### Claim 12 (depends on 9) The terminal according to claim 9, wherein the number of antennas is grouped based on a maximum allowed signaling overhead or a number of free resources. ### Claim 13 (depends on 9) The terminal according to claim 9, wherein: the transmitter is further configured to receive a pilot signal on a downlink channel for each antenna from the BS, and the processor is further configured to obtain the downlink channel estimate value for each antenna from the received pilot signal. ### Claim 14 (depends on 9) The terminal according to claim 9, wherein the normalization value is calculated by the terminal as a function of maximum transmit power of the terminal and the downlink channel estimate value with the lowest signal power. ### Claim 15 (depends on 14) The terminal according to claim 14, wherein the processor is further configured to: obtain the normalization value by multiplying the maximum transmit power of the terminal with a value obtained from the downlink channel estimate value with the lowest signal power. ### Claim 16 (depends on 15) The terminal according to claim 15, wherein the terminal obtains the value as the squared absolute value of the downlink channel estimate value with the lowest signal power. ### Claim 17 A Base Station (BS), having a number of antennas divided into a number of groups of antennas, the BS comprising: a receiver, configured to cooperate with a processor to receive an uplink calibration signal from a terminal, the uplink calibration signal comprising an uplink calibration value for each antenna and a different normalization value for each antenna group, wherein the uplink calibration value is obtained from a downlink channel estimate value for each antenna and the different normalization value for each antenna group; the different normalization value for each antenna group is obtained from a downlink channel estimate value with a lowest signal power within each group, and the processor, configured to process each received uplink calibration value and each received different normalization value into a respective hardware chain value for each antenna of the number of antennas. ### Claim 18 (depends on 17) The BS according to claim 17, wherein the number of antennas is grouped based on a maximum allowed signaling overhead or a number of free resources. ### Claim 19 A calibration method for determining hardware chain values in a Base Station (BS), having a number of antennas grouped in a number of groups, wherein a respective hardware chain value for each antenna of the number of antennas is obtained, the method comprising: receiving, by the BS, an uplink calibration signal from a terminal, the uplink calibration signal comprising an uplink calibration value for each antenna and a different normalization value for each group of antennas, wherein the uplink calibration value is obtained from a downlink channel estimate value for each antenna and the different normalization value for each antenna group; the different normalization value for each antenna group is obtained from a downlink channel estimate value with a lowest signal power within each group, and processing, by the BS, each received uplink calibration value and each received different normalization value into the respective hardware chain value for each antenna. ### Claim 20 (depends on 19) The method according to claim 19, wherein the number of antennas is grouped based on a maximum allowed signaling overhead or a number of free resources.