# US 11,451,312 B2 · Mobile-assisted phase calibration method and system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,312 B2 - Document ID: US11451312B2 - Status: Granted - Kind: B2 - Application number: 17/364,703 - Filed: 2021-06-30 - Published: 2022-01-06 - Granted: 2022-09-20 - Earliest claimed: 2020-07-02 - Assignees: Spirent Communications, Inc. - Applicants: Spirent Communications, Inc. - Inventors: Alfonso Rodriguez-Herrera; John Douglas Reed - Web page: https://patentgrep.com/patent/US11451312B2 ## CPC - H04B 17/12: of transmit antennas, e.g. of the amplitude or phase - H04B 7/0413: MIMO systems - H04B 7/06: at the transmitting station - H04B 17/191: {Over-the-air testing} - H04B 17/327: Received signal code power [RSCP] - H04B: TRANSMISSION ## Abstract Disclosed is a method of calibrating phase alignment of signals from multiple transmit antennas on multiple channels during OTA testing of a MIMO DUT, including generating a noisy test signal by adding noise to a signal pattern and transmitting the noisy test signal to the DUT on first and second channels OTA and sweeping a relative phase of the signal pattern, but not the added noise, in the first and second channels, while receiving from the DUT reports of a SNR for a received signal on at least one of the first channel and subsequently on the second channels. The method also includes analyzing variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT and using the determined phase alignment to perform OTA testing of the DUT. The method can also include receiving a RSRP and/or a RSSI. ## Claims ### Claim 1 A method of calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test, (DUT), including: generating a noisy test signal by adding noise to a signal pattern and transmitting the noisy test signal to the DUT on first and second channels OTA; sweeping a relative phase of the signal pattern, but not the added noise, in the first and second channels, while receiving from the DUT reports of a signal-to-noise ratio (SNR) for a received signal on at least one of the first channel and subsequently on the second channel; analyzing variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT; and using the determined phase alignment to perform OTA testing of the DUT. ### Claim 2 (depends on 1) The method of claim 1, further including: while sweeping a relative phase of the signal pattern, further receiving from the DUT reports of a reference signal received power (RSRP) or a received signal strength indicator (RSSI), for a received signal on at least one of the first and second channels; and combining analysis of variation in the RSRP or RSSI with analysis of variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT. ### Claim 3 (depends on 2) The method of claim 2, wherein the SNR, RSRP and RSSI are all requested at once for a phase sweep iteration. ### Claim 4 (depends on 1) The method of claim 1, wherein the test signal is sourced from a Network Emulator. ### Claim 5 (depends on 1) The method of claim 1, wherein the test signal is sourced from a Base Station. ### Claim 6 (depends on 1) The method of claim 1, wherein a channel emulator (CE) uses an Additive White Gaussian Noise (AWGN) generator to calibrate the SNR reading in the DUT. ### Claim 7 A method of calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test, (DUT), including: generating a noisy test signal by adding noise to a signal pattern and transmitting the noisy test signal to the DUT on first and second channels OTA; sweeping a relative phase of the signal pattern, but not the added noise, in the first and second channels, while receiving from the DUT reports of a reference signal received power (RSRP) or a received signal strength indicator (RSSI), collectively signal measurement, for a received signal on at least one of the first and second channels; analyzing variation in the signal measurement to determine phase alignment of the first and second channels, as received and processed by the DUT; and using the determined phase alignment to perform OTA testing of the DUT. ### Claim 8 (depends on 7) The method of claim 7, wherein the test signal is sourced from a Network Emulator. ### Claim 9 (depends on 7) The method of claim 7, wherein the test signal is sourced from a Base Station. ### Claim 10 (depends on 7) The method of claim 7, wherein a channel emulator (CE) uses its output power set points to calibrate the RSSI and RSRP readings in the DUT. ### Claim 11 A tangible non-transitory computer readable storage media, loaded with program instructions that, when executed on processors, cause the processors to implement a method of calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test (DUT), the method including: generating a noisy test signal by adding noise to a signal pattern and transmitting the noisy test signal to the DUT on first and second channels OTA; sweeping a relative phase of the signal pattern, but not the added noise, in the first and second channels, while receiving from the DUT reports of a signal-to-noise ratio (SNR) for a received signal on at least one of the first channel and subsequently on the second channel; analyzing variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT; and using the determined phase alignment to perform OTA testing of the DUT. ### Claim 12 (depends on 11) The tangible non-transitory computer readable storage media of claim 11, further including: while sweeping a relative phase of the signal pattern, further receiving from the DUT reports of a reference signal received power (RSRP) or a received signal strength indicator (RSSI), for a received signal on at least one of the first and second channels; and combining analysis of variation in the RSRP or RSSI with analysis of variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT. ### Claim 13 (depends on 12) The tangible non-transitory computer readable storage media of claim 12, wherein the SNR, RSRP and RSSI are all requested at once for a phase sweep iteration. ### Claim 14 (depends on 11) A system for calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test (DUT), the system including a processor, memory coupled to the processor and computer instructions from the non-transitory computer readable storage media of claim 11 loaded into the memory. ### Claim 15 (depends on 14) The system of claim 14, wherein the test signal is sourced from a Network Emulator. ### Claim 16 (depends on 14) The system of claim 14, wherein the test signal is sourced from a Base Station. ### Claim 17 A tangible non-transitory computer readable storage media, loaded with program instructions that, when executed on processors, cause the processors to implement a method of calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test (DUT), the method including: generating a noisy test signal by adding noise to a signal pattern and transmitting the noisy test signal to the DUT on first and second channels OTA; sweeping a relative phase of the signal pattern, but not the added noise, in the first and second channels, while receiving from the DUT reports of a reference signal received power (RSRP) or a received signal strength indicator (RSSI), collectively signal measurement, for a received signal on at least one of the first and second channels; analyzing variation in the signal measurement to determine phase alignment of the first and second channels, as received and processed by the DUT; and using the determined phase alignment to perform OTA testing of the DUT. ### Claim 18 (depends on 17) A system for calibrating phase alignment of signals from multiple transmit antennas on multiple channels during over-the-air (OTA) testing of a multiple-input multiple-output (MIMO) device under test (DUT), the system including a processor, memory coupled to the processor and computer instructions from the non-transitory computer readable storage media of claim 17 loaded into the memory. ### Claim 19 (depends on 18) The system of claim 18, further configurable to carry out a method including: while sweeping a relative phase of the signal pattern, further receiving from the DUT reports of a reference signal received power (RSRP) or a received signal strength indicator (RSSI), for a received signal on at least one of the first and second channels; and combining analysis of variation in the RSRP or RSSI with analysis of variation in the SNR to determine phase alignment of the first and second channels, as received and processed by the DUT. ### Claim 20 (depends on 19) The system of claim 19, wherein the SNR, RSRP and RSSI are all requested at once for a phase sweep iteration.