# US 10,374,735 B2 · Communication system, communication system control method, transmission device, and reception device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,735 B2 - Document ID: US10374735B2 - Status: Granted - Kind: B2 - Application number: 14/898,990 - Filed: 2014-05-19 - Published: 2016-05-12 - Granted: 2019-08-06 - Earliest claimed: 2013-06-18 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Kazuki Shibata - Web page: https://patentgrep.com/patent/US10374735B2 ## CPC - H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)} - H04J 3/0673: {using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet} - 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 counter is synchronized with a counter within a communication device and measures, as a first count value, a timing before a PTP packet is input to a processing unit that performs processing on the PTP packet. A multiplexing unit multiplexes the first count value into the PTP packet. The counter measures, as a second count value, a timing when processing by a processing unit that performs processing on the PTP packet is completed. A count extraction unit extracts the first count value from the PTP packet. A modification unit modifies a correction field by calculating a modification value based on the second count value, the first count value, and a value of the correction field within the PTP packet, the value of the correction field indicating a total amount of delay in a relay device. ## Claims ### Claim 1 A communication system comprising: a transmission device that transmits a time synchronization packet for time synchronization; and a reception device that receives the time synchronization packet, wherein the transmission device includes: a first counter that is synchronized with a second counter within the reception device, and measures, as a first count value, a timing before the time synchronization packet is input for performing processing on the time synchronization packet; and wherein the transmission device multiplexes the first count value into the time synchronization packet; and the reception device includes: the second counter that measures, as a second count value, a timing when performing processing on the time synchronization packet is completed; wherein the reception device extracts the first count value from the time synchronization packet; and wherein the reception device modifies a delay amount field by calculating a modification value based on the second count value, the first count value, and a value of the delay amount field within the time synchronization packet, the value of the delay amount field indicating a total amount of delay in a relay device, wherein: when the first count value is greater than the second count value, the reception device modifies the delay amount field by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value and a maximum count value of the second counter, and when the second count value is greater than the first count value, the reception device modifies the delay amount field by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value. ### Claim 2 (depends on 1) The communication system according to claim 1, wherein the reception device modifies the delay amount field by adding a fixed delay value to the modification value, the fixed delay value being generated in communication between the transmission device and the reception device. ### Claim 3 (depends on 1) The communication system according to claim 1, wherein the reception device and the transmission device periodically transmit and receive a transmission frame which may include the time synchronization packet, and the transmission device adjusts a count value of the first counter based on a timing of detecting an overhead of the transmission frame, and the reception device synchronizes the counters by adjusting the second count value based on the timing of detecting the overhead of the transmission frame. ### Claim 4 (depends on 3) The communication system according to claim 3, wherein the transmission device adjusts a count value of the first counter at each timing of detecting the overhead of the transmission frame by using a multiplication value N obtained by multiplying an operating frequency f of the first counter by an ideal detection period S of the overhead of the transmission frame. ### Claim 5 (depends on 3) The communication system according to claim 3, wherein the reception device adjusts a count value of the second counter at each timing of detecting the overhead of the transmission frame by using a multiplication value N obtained by multiplying an operating frequency f of the second counter by an ideal detection period S of the overhead of the transmission frame. ### Claim 6 (depends on 1) The communication system according to claim 1, wherein one of the reception device and the transmission device transmits, to the other one of the reception device and the transmission device, configuration information indicating whether the delay amount field is modified or not, and when there is a difference between a configuration for modifying the delay amount field in the reception device and that in the transmission device, the former configuration is set to be the same as the latter. ### Claim 7 (depends on 1) The communication system according to claim 1, wherein a maximum count value of the first counter is equal to a maximum count value of the second counter. ### Claim 8 A control method for a communication system, the communication system comprising: a transmission device that transmits a time synchronization packet for time synchronization; and a reception device that receives the time synchronization packet, the control method comprising: a first counting step of establishing, by the transmission device, synchronization with a second counter within the reception device and measuring, as a first count value, a timing before the time synchronization packet is input to for performing processing on the time synchronization packet; a multiplexing step of multiplexing, by the transmission device, the first count value into the time synchronization packet and transmitting the time synchronization packet to the reception device; a second counting step of measuring, by the reception device, a timing when performing processing on the time synchronization packet is completed, as a second count value; an extraction step of extracting, by the reception device, the first count value from the time synchronization packet; and a modification step of modifying, by the reception device, a delay amount field by calculating a modification value based on the second count value, the first count value, and a value of the delay amount field within the time synchronization packet, the value of the delay amount field indicating a total amount of delay in a relay device, wherein: when the first count value is greater than the second count value, the delay amount field is modified by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value and a maximum count value of the second counter, and when the second count value is greater than the first count value, the delay amount field is modified by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value. ### Claim 9 (depends on 8) The control method for a communication system according to claim 8, wherein in the modification step, the delay amount field is modified by adding a fixed delay value to the modification value, the fixed delay value being generated in communication between the transmission device and the reception device. ### Claim 10 (depends on 8) The control method for a communication system according to claim 8, wherein the reception device and the transmission device periodically transmit and receive a transmission frame which may include the time synchronization packet, and the transmission device adjusts a count value of a first counter based on a timing of detecting an overhead of the transmission frame, and the reception device synchronizes the counters by adjusting the second count value based on the timing of detecting the overhead of the transmission frame. ### Claim 11 (depends on 10) The control method for a communication system according to claim 10, wherein the transmission device adjusts the count value of the first counter at each timing of detecting the overhead of the transmission frame by using a multiplication value N obtained by multiplying an operating frequency f of the first counter by an ideal detection period S of the overhead of the transmission frame. ### Claim 12 (depends on 10) The control method for a communication system according to claim 10, wherein the reception device adjusts a count value of the second counter at each timing of detecting the overhead of the transmission frame by using a multiplication value N obtained by multiplying an operating frequency f of the second counter by an ideal detection period S of the overhead of the transmission frame. ### Claim 13 (depends on 8) The control method for a communication system according to claim 8, wherein one of the reception device and the transmission device transmits, to the other one of the reception device and the transmission device, configuration information indicating whether the delay amount field is modified or not, and when there is a difference between a configuration for modifying the delay amount field in the reception device and that in the transmission device, the former configuration is set to be the same as the latter. ### Claim 14 A reception device that receives a time synchronization packet for time synchronization, the reception device comprising: a second counter that measures, as a second count value, a timing when performing processing on the time synchronization packet is completed; wherein the reception devices is configured to extract a first count value from the time synchronization packet; and wherein the reception devices is configured to modify a delay amount field by calculating a modification value based on the second count value, the first count value, and a value of the delay amount field within the time synchronization packet, the value of the delay amount field indicating a total amount of delay in a relay device, wherein: when the first count value is greater than the second count value, the reception device modifies the delay amount field by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value and a maximum count value of the second counter, and when the second count value is greater than the first count value, the reception device modifies the delay amount field by using, as the modification value, a value obtained by subtracting the first count value from the value of the delay amount field and adding the second count value. ### Claim 15 (depends on 14) The reception device according to claim 14, wherein the reception device modifies the delay amount field by adding a fixed delay value to the modification value, the fixed delay value being generated in communication between the reception device and a transmission device that transmits the time synchronization packet. ### Claim 16 (depends on 14) The reception device according to claim 14, wherein the reception device and a transmission device that transmits the time synchronization packet periodically transmit and receive a transmission frame which may include the time synchronization packet, and the reception device synchronizes the second counter with a first counter by adjusting the second count value based on a timing of detecting an overhead of the transmission frame. ### Claim 17 (depends on 16) The reception device according to claim 16, wherein the reception device adjusts a count value of the second counter at each timing of detecting the overhead of the transmission frame by using a multiplication value N obtained by multiplying an operating frequency f of the second counter by an ideal detection period S of the overhead of the transmission frame.