# US 9,882,799 B2 · Assigning time stamps to received data packets > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,882,799 B2 - Document ID: US9882799B2 - Status: Granted - Kind: B2 - Application number: 14/736,528 - Filed: 2015-06-11 - Published: 2015-10-01 - Granted: 2018-01-30 - Earliest claimed: 2012-12-12 - Assignees: Bayerische Motoren Werke Aktiengesellschaft - Applicants: Bayerische Motoren Werke Aktiengesellschaft - Inventors: Horst Kloeden; Felix Klanner; Armin Bartsch; Andreas Rauch - Web page: https://patentgrep.com/patent/US9882799B2 ## CPC - H04L 43/106: using time related information in packets, e.g. by adding timestamps - H04J 3/0658: {Clock or time synchronisation among packet nodes} - H04L 43/067: using time frame reporting - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract A method is provided for assigning a time stamp to a specific data packet which, as with a group of received data packets, is received by a cyclically operating sensor. The specific data packet especially is part of the group of received data packets. The method includes: determining the time of arrival of each data packet of the group of received data packets; assigning a time stamp to each data packet of the group of data packets based on a first reference point in time; determining the time difference between the determined time of arrival and the assigned time stamp for each data packet of the group of data packets to provide a group of time differences; determining negative time differences from among the group of time differences, for the data packets of which it has been determined that the time of arrival preceded the respective assigned time stamp; determining the negative time differences that are not to be classified as outliers; determining a second reference point in time taking into account the negative time differences that are not to be classified as outliers; and assigning a time stamp to the specific data packet based on the second reference point in time. ## Claims ### Claim 1 A method for assigning a time stamp to a specific data packet which, as with a group of received data packets, is received by a cyclically operating sensor, wherein the specific data packet is part of the group of received data packets, the method comprising the acts of: determining an arrival time for each data packet of the group of received data packets; assigning a time stamp to each data packet of the group of data packets based on a first reference instant; determining a time difference between the determined arrival time and the assigned time stamp for each data packet of the group of data packets to provide a group of time differences; determining negative time differences from the group of time differences for the data packets where the arrival time was determined to precede the respective assigned time stamp; determining the negative time differences which are not to be classified as outliers; determining a second reference instant taking into account the negative time differences which are not to be classified as outliers; and assigning a time stamp to the specific data packet based on the second reference instant. ### Claim 2 (depends on 1) The method according to claim 1, wherein the act of determining the negative time differences which are not to be classified as outliers comprises the following acts of: determining a threshold value on the basis of the determined negative time differences; and determining the negative time differences of which the magnitude is smaller than a magnitude of the threshold value. ### Claim 3 (depends on 2) The method according to claim 2, wherein the threshold value is determined based on one of the following conditions: a variance of the negative time differences; a variance of the negative time differences which lie in a quantile of the time differences; and a variance of the negative time differences of which the magnitude is smaller than a maximum value. ### Claim 4 (depends on 3) The method according to claim 3, wherein the threshold value is determined based on a multiple of a square root of the variances used to determine the threshold value. ### Claim 5 (depends on 4) The method according to claim 4, wherein the multiple is an odd-number. ### Claim 6 (depends on 3) The method according to claim 3, wherein the variances of the negative time differences which lie in the quantile of the time differences lie in a 90th or 95th percentile. ### Claim 7 (depends on 2) The method according to claim 2, wherein the act of determining the threshold value comprises the following acts of: forming clusters of the negative time differences; and determining the threshold value based on a boundary between two clusters. ### Claim 8 (depends on 1) The method according to claim 1, wherein the act of determining the negative time differences which are not to be classified as outliers comprises the following acts of: forming clusters of the negative time differences; and determining one or more of the clusters to be classified as outliers. ### Claim 9 (depends on 1) The method according to claim 1, wherein the act of determining the second reference instant taking into account the negative time differences which are not to be classified as outliers comprises the following acts of: selecting a single time difference from the negative time differences which are not to be classified as outliers; and setting the second reference instant to the arrival time of the data packet for which the arrival time of the selected single time difference has been determined. ### Claim 10 (depends on 9) The method according to claim 9, wherein the act of selecting the single time difference comprises the following acts of: selecting the negative time difference of which a magnitude is greater than the magnitudes of the remaining negative time differences which are not to be classified as outliers; or selecting the negative time difference which forms a boundary element of a quantile of the negative time differences which are not to be classified as outliers. ### Claim 11 (depends on 10) The method according to claim 10, wherein the boundary element of the quantile is a 90th percentile. ### Claim 12 (depends on 9) The method according to claim 9, wherein the act of determining the second reference instant taking into account the negative time differences which are not to be classified as outliers further takes into account one or more of the following criteria: a total number of data packets received by the sensor since the start-up of a system performing the method; a transit time since the start-up of a system performing the method; a number of determinations of a reference instant since the start-up of a system performing the method; and a size of the magnitudes or a statistic measure of the size of the magnitudes of all determined negative time differences since the start-up of a system performing the method. ### Claim 13 (depends on 1) The method according to claim 1, wherein the act of determining the second reference instant taking into account the negative time differences which are not to be classified as outliers comprises the following acts of: determining a descriptive value, for the negative time differences or a subgroup of the negative time differences which are not to be classified as outliers; and setting the second reference instant to the descriptive value. ### Claim 14 (depends on 13) The method according to claim 13, wherein the descriptive value is a statistical measure. ### Claim 15 (depends on 13) The method according to claim 13, wherein the descriptive value is one of the following values: an average of the negative time differences, or a subgroup thereof, which are not to be classified as outliers; or a median of the negative time differences, or a subgroup thereof, which are not to be classified as outliers. ### Claim 16 (depends on 15) The method according to claim 15, wherein the subgroup of the negative time differences is a subgroup quantile of the negative time differences. ### Claim 17 (depends on 1) The method according to claim 1, wherein the group of data packets comprises a minimum number of data packets and/or wherein the specific data packet is included in the group of data packets or is received later as the last-received data packet of the group. ### Claim 18 A motor vehicle, comprising: an electronic controller including a memory storing a program having program code segments; and an associated processor for executing the program code segments to: determine an arrival time for each data packet of the group of received data packets; assign a time stamp to each data packet of the group of data packets based on a first reference instant; determine a time difference between the determined arrival time and the assigned time stamp for each data packet of the group of data packets to provide a group of time differences; determine negative time differences from the group of time differences for the data packets where the arrival time was determined to precede the respective assigned time stamp; determine the negative time differences which are not to be classified as outliers; determine a second reference instant taking into account the negative time differences which are not to be classified as outliers; and assign a time stamp to the specific data packet based on the second reference instant. ### Claim 19 A computer product, comprising a non-transitory computer readable medium having stored thereon program code segments that: determine an arrival time for each data packet of the group of received data packets; assign a time stamp to each data packet of the group of data packets based on a first reference instant; determine a time difference between the determined arrival time and the assigned time stamp for each data packet of the group of data packets to provide a group of time differences; determine negative time differences from the group of time differences for the data packets where the arrival time was determined to precede the respective assigned time stamp; determine the negative time differences which are not to be classified as outliers; determine a second reference instant taking into account the negative time differences which are not to be classified as outliers; and assign a time stamp to the specific data packet based on the second reference instant.