# US 11,909,127 B2 · Antenna system, calibration unit, and calibration method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,127 B2 - Document ID: US11909127B2 - Status: Granted - Kind: B2 - Application number: 17/434,114 - Filed: 2020-01-27 - Published: 2022-05-05 - Granted: 2024-02-20 - Earliest claimed: 2019-02-28 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Tung Nguyen - Web page: https://patentgrep.com/patent/US11909127B2 ## CPC - H01Q 3/267: {Phased-array testing or checking devices} - H04B 7/06: at the transmitting station - H04B 17/12: of transmit antennas, e.g. of the amplitude or phase - H04B 7/0413: MIMO systems - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H04B: TRANSMISSION ## Abstract A reference signal generator generates a reference signal having high auto-correlation. A delay unit delays the reference signal to generate delayed reference signals and outputs the reference signal and the delayed reference signals to the transmission units, respectively. A calibration network combines the output signals of the transmission units. An analyzer analyzes a correlation between a demodulated signal and the reference signal to determine variations of timing, amplitude and a phase of the output signal of each transmission unit. Each transmission unit calibrates the timing, amplitude and phase of the output signal based on a corresponding determination result. ## Claims ### Claim 1 An antenna system comprising: an antenna comprising a plurality of antenna elements; a plurality of transmission units, the transmission units modulating input signals and output the modulated signals as output signals to the antenna elements, respectively; a reference signal generator configured to generate a reference signal having high auto-correlation; a delay unit configured to delay the reference signal to generate delayed reference signals having delay amounts different from each other and to output the reference signal and the delayed reference signals to the transmission units, respectively; a calibration network configured to combines the output signals of the transmission units; and an analyzer configured to analyze a correlation between a signal obtained by demodulating a combined signal output from the calibration network and the reference signal to determine variations of timing, amplitude and a phase of the output signal of each transmission unit, and to notify the transmission units of determination results, wherein each transmission unit calibrates the timing, amplitude and phase of the output signal based on a corresponding determination result. ### Claim 2 (depends on 1) The antenna system according to claim 1, wherein the reference signal having high auto-correlation is a pseudo noise (PN) sequence. ### Claim 3 (depends on 2) The antenna system according to claim 2, further comprising a receiver configured to demodulate the combined signal and output the demodulated signal to the analyzer. ### Claim 4 (depends on 2) The antenna system according to claim 2, wherein a receiver disposed in another antenna system demodulates the combined signal and output the demodulated signal to the analyzer. ### Claim 5 (depends on 2) The antenna system according to claim 2, wherein the delay unit delays the reference signal to generate N−1 PN sequences that are delayed by Δt to (N−1)*fit, respectively, where N is an integer equal to or more than two, and the reference signal and the N−1 PN sequences are output to N transmission units, respectively. ### Claim 6 (depends on 2) The antenna system according to claim 2, wherein the analyzer determines the timing of the PN sequence based on a position along a time axis of a corresponding peak in a power level of the correlation, determines the amplitude of the PN sequence based on a power level of the corresponding peak in the power level of the correlation, and determines the phase of the PN sequence based on a jump of a corresponding peak in a phase of the correlation. ### Claim 7 (depends on 6) The antenna system according claim 6, wherein the timing and amplitude of each PN sequence are calibrated based on the power level of the correlation between the received signal and reference signal that is firstly obtained, and the phase of each PN sequence is calibrated based on the phase of the correlation between the received signal and reference signal that is obtained after the timing and amplitude of each PN sequence have been calibrated. ### Claim 8 An calibration unit comprising: a reference signal generator configured to generate a reference signal having high auto-correlation; a delay unit configured to delay the reference signal to generate delayed reference signals having delay amounts different from each other and to respectively output the reference signal and the delayed reference signals to transmission units, the transmission units respectively modulating input signals and output the modulated signals as output signals to the antenna elements; a calibration network configured to combines the output signals of the transmission units; and an analyzer configured to analyze a correlation between a signal obtained by demodulating a combined signal output from the calibration network and the reference signal to determine variations of timing, amplitude and a phase of the output signal of each transmission unit, and to notify the transmission units of determination results, wherein each transmission unit calibrates the timing, amplitude and phase of the output signal based on a corresponding determination result. ### Claim 9 (depends on 8) The calibration unit according to claim 8, wherein the reference signal having high auto-correlation is a pseudo noise (PN) sequence. ### Claim 10 (depends on 9) The calibration unit according to claim 9, wherein the antenna elements, the transmission units and a receiver configured to demodulate the combined signal and output the demodulated signal to the analyzer are included in an antenna system. ### Claim 11 (depends on 9) The calibration unit according to claim 9, wherein the antenna elements and the transmission units are included in a first antenna system, and a receiver configured to demodulate the combined signal and output the demodulated signal to the analyzer are included in a second antenna system that is different from the first antenna system. ### Claim 12 (depends on 9) The calibration unit according to claim 9, wherein the delay unit delays the reference signal to generate N−1 PN sequences that are delayed by Δt to (N−1)*fit, respectively, where N is an integer equal to or more than two, and the reference signal and the N−1 PN sequences are output to N transmission units, respectively. ### Claim 13 (depends on 9) The calibration unit according to claim 9, wherein the analyzer determines the timing of the PN sequence based on a position along a time axis of a corresponding peak in a power level of the correlation, determines the amplitude of the PN sequence based on a power level of the corresponding peak in the power level of the correlation, and determines the phase of the PN sequence based on a jump of a corresponding peak in a phase of the correlation. ### Claim 14 (depends on 13) The calibration unit according to claim 13, wherein the timing and amplitude of each PN sequence are calibrated based on the power level of the correlation between the received signal and reference signal that is firstly obtained, and the phase of each PN sequence is calibrated based on the phase of the correlation between the received signal and reference signal that is obtained after the timing and amplitude of each PN sequence have been calibrated. ### Claim 15 A calibration method comprising: generating a reference signal having high auto-correlation; delaying the reference signal to generate delayed reference signals having delay amounts different from each other; outputting the reference signal and the delayed reference signals to transmission units, respectively, the transmission units respectively modulating input signals and output the modulated signals as output signals to the antenna elements; combining the output signals of the transmission units to generate a combined signal; and analyzing a correlation between a signal obtained by demodulating the combined signal and the reference signal to determine variations of timing, amplitude and a phase of the output signal of each transmission unit; notifying the transmission units of determination results, wherein each transmission unit calibrates the timing, amplitude and phase of the output signal based on a corresponding determination result. ### Claim 16 (depends on 15) The calibration method according to claim 15, wherein the reference signal having high auto-correlation is a pseudo noise (PN) sequence. ### Claim 17 (depends on 16) The calibration method according to claim 16, wherein the antenna elements, the transmission units and a receiver configured to demodulate the combined signal and output the demodulated signal to the analyzer are included in an antenna system. ### Claim 18 (depends on 16) The calibration method according to claim 16, wherein the antenna elements and the transmission units are included in a first antenna system, and a receiver configured to demodulate the combined signal and output the demodulated signal to the analyzer are included in a second antenna system that is different from the first antenna system. ### Claim 19 (depends on 16) The calibration method according to claim 16, wherein the reference signal is delayed to generate N−1 PN sequences that are delayed by Δt to (N−1)*fit, respectively, where N is an integer equal to or more than two, and the reference signal and the N−1 PN sequences are output to N transmission units, respectively. ### Claim 20 (depends on 16) The calibration method according to claim 16, wherein the timing of the PN sequence is determined based on a position along a time axis of a corresponding peak in a power level of the correlation, the amplitude of the PN sequence is determined based on a power level of the corresponding peak in the power level of the correlation, and the phase of the PN sequence is determined based on a jump of a corresponding peak in a phase of the correlation.