# US 12,119,960 B2 · Method for improved synchronization between a transmitter and a receiver on a wireless network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,119,960 B2 - Document ID: US12119960B2 - Status: Granted - Kind: B2 - Application number: 18/504,496 - Filed: 2023-11-08 - Published: 2024-04-18 - Granted: 2024-10-15 - Earliest claimed: 2021-01-15 - Assignees: Morse Micro Pty. Ltd. - Applicants: Morse Micro Pty. LTD. - Inventors: Peter Bradley; Eyal Mendel - Web page: https://patentgrep.com/patent/US12119960B2 ## CPC - H04L 25/022: {of frequency response} - H04L 27/2657: {Carrier synchronisation} - H04L 25/03006: {Arrangements for removing intersymbol interference} - H04L 25/497: by correlative coding, e.g. partial response coding or echo modulation coding {transmitters and receivers for partial response systems (transversal equalizers at the transmitter end H04L25/03343)} - H04L 27/2663: {Coarse synchronisation, e.g. by correlation} - H04L 2025/03815: {Transmission of a training request} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present disclosure provides a method for estimating timing and/or frequency of a wireless signal; the method including the steps: receiving a digitally modulated signal; extracting a plurality of signal samples associated with a short training field (STF) of a PHY protocol data unit (PPDU) of an 802.11 frame; performing correlation operations on the plurality of signal samples to generate a predetermined number of correlation peaks; comparing the generated correlation peaks with a variable dynamic threshold; and calculating timing and/or frequency of the digitally modulated signal using the outcome of the comparing step. ## Claims ### Claim 1 A method for estimating timing and/or frequency of a wireless signal; the method comprising the steps: receiving a digitally modulated signal; extracting a plurality of signal samples associated with a short training field (STF) of a PHY protocol data unit (PPDU) of a frame; performing correlation operations on the plurality of signal samples to generate a number of correlation peaks comparing the generated correlation peaks with a variable dynamic threshold; and calculating timing and/or frequency of the digitally modulated signal using the outcome of the comparing step; wherein comparing the generated correlation peaks with the variable dynamic threshold is performed in time windows only; and within each of the time windows, the generated correlation peaks are compared with the variable dynamic threshold, whilst outside of the time windows the generated correlation peaks are compared with a highest correlation peak detected for the digitally modulated signal. ### Claim 2 (depends on 1) The method of claim 1, wherein the variable dynamic threshold is configured to minimize a number of false peak detections. ### Claim 3 (depends on 1) The method of claim 1, wherein the variable dynamic threshold decreases with a distance from a last detected correlation peak. ### Claim 4 (depends on 1) The method of claim 1, wherein the variable dynamic threshold is calculated by applying low-pass filtering to the correlation peaks. ### Claim 5 (depends on 1) The method of claim 1, wherein the time windows are calculated based on an expected frequency of the correlation peaks. ### Claim 6 (depends on 1) The method of claim 1, wherein, if a correlation peak higher than the highest correlation peak is detected outside of the time windows thereby forming a new higher peak, a frequency and/or timing estimation process is restarted based on the new higher peak. ### Claim 7 (depends on 6) The method of claim 6, wherein the estimation process is restarted only if a number of correlation peaks detected is lower than a predetermined minimum number of correlation peaks. ### Claim 8 (depends on 1) The method of claim 1, wherein the step of performing correlation operations on the plurality of signal samples to generate a number of correlation peaks comprises autocorrelating the plurality of signal samples. ### Claim 9 (depends on 1) The method of claim 1, wherein the step of performing correlation operations on the plurality of signal samples to generate a number of correlation peaks comprises averaging phase differences of the signal samples. ### Claim 10 (depends on 1) The method of claim 1, further comprising reducing the variable dynamic threshold after a first correlation peak has been detected to optimize the probability of detecting another correlation peak. ### Claim 11 (depends on 1) The method of claim 1, further comprising reducing the variable dynamic threshold once a predetermined number of correlation peaks related to the STF for the PPDU have been detected. ### Claim 12 (depends on 1) The method of claim 1, further comprising increasing the variable dynamic threshold after a predetermined amount of time corresponding with the duration of the STF, to minimize the probability of detection of a long training field (LTF) side lobe. ### Claim 13 (depends on 1) The method of claim 1, further comprising comparing one or more correlation peaks related to the STF with a long training field (LTF) timing point to determine whether any detected correlation peaks should be discarded. ### Claim 14 (depends on 1) The method of claim 1, wherein the method further comprises sensing an amount of energy on an wireless medium (WM) and setting a value of the variable dynamic threshold based on the amount of energy. ### Claim 15 (depends on 1) The method of claim 1, wherein the method further comprises sensing a baseline noise present on a channel and setting a value of the variable dynamic threshold based on the baseline noise. ### Claim 16 (depends on 1) The method of claim 1, wherein the step of performing correlation operations on the plurality of signal samples to generate a number of correlation peaks comprises cross-correlating the plurality of signal samples across at least 3 correlation peaks. ### Claim 17 (depends on 1) The method of claim 1, further comprising determining whether a false peak detection has occurred using one or more of the following steps: restarting peak detection if a required number of correlation peaks is not detected in a predetermined time window; calculating an average signal to noise ratio (SNR) metric from detected correlation peaks and determining a difference between a genuine pattern of correlation peaks related to a STF and a false detection pattern; detecting a correlation peak with maximum intensity before reaching a required minimum number of correlation peaks; and detecting a large sudden change in correlation peak strength before a minimum number of correlation peaks is detected. ### Claim 18 A device for estimating timing and/or frequency of a wireless signal, the device comprising: a receiver module configured to receive a digitally modulated signal; an antenna unit communicatively coupled to the receiver module; a packet detect module configured to analyze a PHY protocol data unit (PPDU), the PPDU having a plurality of signal samples associated therewith; a correlator configured to perform operations on the plurality of signal samples; and at least one processor and memory, the memory having software that when executed by the at least one processor causes the at least one processor to perform operations, the operations comprising; receiving the digitally modulated signal, extracting the plurality of signal samples associated with a short training field (STF) of the PPDU of a frame, performing correlation operations on the plurality of signal samples to generate a number of correlation peaks, comparing the generated correlation peaks with a variable dynamic threshold, and calculating timing and/or frequency of the digitally modulated signal using the outcome of the comparing step, wherein comparing the generated correlation peaks with the variable dynamic threshold is performed in time windows only, and within each of the time windows, the generated correlation peaks are compared with the variable dynamic threshold, whilst outside of the time windows the generated correlation peaks are compared with a highest correlation peak detected for the digitally modulated signal. ### Claim 19 (depends on 18) The device of claim 18, the operations further comprising, if a correlation peak higher than the highest correlation peak is detected outside of the time windows thereby forming a new higher peak, a frequency and/or timing estimation process is restarted based on the new higher peak. ### Claim 20 (depends on 18) The device of claim 18, the operations further comprising restarting the estimation process only if a number of correlation peaks detected is lower than a predetermined minimum number of correlation peaks.