Time-Synchronizing a Group of Nodes

• US 20150295700A1
• Filed: 04/10/2014
• Published: 10/15/2015
• Est. Priority Date: 04/10/2014
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: GOMEZ GUTIERREZ, DAVID, PARRA VILCHIS, JOSE, DE LA GUARDIA GONZALEZ, RAFAEL
• Granted Patent: US 9,952,620 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: G06F 11/1675 Temporal synchronisation or re-synchronisation of redundant processing components
• CPC Class Codes: H04J 3/0635 Clock or time synchronisation in a network timer in protocols H04L69/28
• CPC Class Codes: H04L 7/0008 Synchronisation information channels, e.g. clock distribution lines
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

Systems and methods include receiving, values of one or more first external time variables from a first external node and values of one or more second external time variables from a second external node. The values of one or more local time variables of the local node are adjusted based at least upon the values of the one or more first external time variables and the values of the one or more second external time variables.

Claims

1. A node configured to time synchronize with other nodes, the node comprising:

a processor;

a communication module operated by the processor, configured to receive first values of one or more first external time variables from a first external node and second values of one or more second external time variables from a second external node; and

a local time-update module operated by the processor, coupled to the communication module, wherein the time-update module is configured to adjust values of one or more local time variables based at least upon the first values of the one or more first external time variables and the second values of the one or more second external time variables.

2. The node of claim 1, further comprising a local clock module operated by the processor,

wherein the values of the one or more local time variables are based at least upon values obtained from the local clock module,

wherein the first values of the one or more first external time variables are based at least upon a first external clock module at the first external node,

wherein the second values of the one or more second external time variables are based at least upon a second external clock module at the second external node, and

wherein the local clock module, the first external clock module, and the second external clock module drift over time from each other in at least one of phase or frequency.

3. The node of claim 1,

wherein the first values of the one or more first external time variables are indicative of a first external time value of the first external node,

wherein the second values of the one or more second external time variables are indicative of a second external time value of the second external node, and

wherein the values of the one or more local time variables are indicative of a local time value of the node.

4. The node of claim 3, wherein:

a first time of reception of the first external time variables is independent of a first phase of the first time, and

a second time of reception of the second external time variables is independent of a second phase of the second time.

5. The node of claim 3, wherein the adjusting the values of the one or more local time variables causes the local time value to shift closer to at least one of the first external time value or to the second external time value.

6. The node of claim 3, wherein:

the communication module is configured to transmit values of the one or more local time variables,

wherein another external node of a set of external nodes is configured to;

receive the values of the one or more local time variables, and

adjust values of one or more other external time variables of the other external node based at least upon the values of the one or more local time variables, wherein the values of the one or more other external time variables are indicative of another external time value of the other external time node.

7. The node of claim 3, wherein:

the local time variables indicate a state of a local logical oscillator designed to define the local time value,

the first external time variables indicate a state of a first external logical oscillator designed to define the first external time value, and

the second external time variables indicate a state of a second external logical oscillator designed to define the second external time value.

8. The node of claim 1, further comprising a trustworthiness module operated by the processor, configured to determine a first trustworthiness of the first external node and a second trustworthiness of the second external node,

wherein the local time-update module is configured to adjust the values of the one or more local time variables based upon the first trustworthiness and the second trustworthiness.

9. The node of claim 1, wherein:

a first act of transmitting the first external time variables by the first external node is independent of the first external time value, and

a second act of transmitting the second external time variables by the second external node is independent of the second external time value.

10. A method for time-synchronizing nodes, the method comprising:

receiving, at a local node, first values of one or more first external time variables from a first external node and second values of one or more second external time variables from a second external node; and

adjusting, by a software local time-update module executing on one or more processing units, values of one or more local time variables of the local node based at least upon the first values of the one or more first external time variables and the second values of the one or more second external time variables.

11. The method of claim 10:

wherein the values of the one or more local time variables are based at least upon values obtained from a local physical oscillator at the local node,

wherein the first values of the one or more first external time variables are based at least upon a first external physical oscillator at the first external node,

wherein the second values of the one or more second external time variables are based at least upon a second external physical oscillator at the second external node, and

wherein the local physical oscillator, the first external physical oscillator, and the second external physical oscillator drift over time from each other in at least one of phase or frequency.

12. The method of claim 10,

wherein the first values of the one or more first external time variables are indicative of a first external time value of the first external node,

wherein the second values of the one or more second external time variables are indicative of a second external time value of the second external node, and

wherein the values of the one or more local time variables are indicative of a local time value of the local node.

13. The method of claim 12, wherein:

a first time of reception of the first external time variables is independent of a first phase of the first time, and

a second time of reception of the second external time variables is independent of a second phase of the second time.

14. The method of claim 12, wherein the adjusting the values of the one or more local time variables causes the local time value to shift closer to at least one of the first external time value or the second external time value.

15. The method of claim 12, comprising:

transmitting, from the local node, values of the one or more local time variables,

wherein another external node of a set of external nodes is configured to;

receive the values of the one or more local time variables; and

adjust values of one or more other external time variables of the other external node based at least upon the values of the one or more local time variables, wherein the values of the one or more other external time variables are indicative of another external time value of the other external time node.

16. The method of claim 10, comprising:

determining a first trustworthiness of the first external node and a second trustworthiness of the second external node; and

adjusting the values of the one or more local time variables based upon the first trustworthiness and the second trustworthiness.

17. At least one non-transitory, machine-accessible storage medium having instructions stored thereon, wherein the instructions are configured, when executed on a machine, to cause the machine to:

receive, at a local node, first values of one or more first external time variables from a first external node and second values of one or more second external time variables from a second external node; and

adjust values of one or more local time variables of the local node based at least upon the first values of the one or more first external time variables and the second values of the one or more second external time variables.

18. The at least one storage medium of claim 17:

wherein the values of the one or more local time variables are based at least upon values obtained from a local physical oscillator at the local node,

wherein the first values of the one or more first external time variables are based at least upon a first external physical oscillator at the first external node,

wherein the second values of the one or more second external time variables are based at least upon a second external physical oscillator at the second external node, and

wherein the local physical oscillator, the first external physical oscillator, and the second external physical oscillator drift over time from each other in at least one of phase or frequency.

19. The at least one storage medium of claim 17,

wherein the first values of the one or more first external time variables are indicative of a first external time value of the first external node,

wherein the second values of the one or more second external time variables are indicative of a second external time value of the second external node, and

wherein the values of the one or more local time variables are indicative of a local time value of the local node.

20. The at least one storage medium of claim 19, wherein:

a first time of reception of the first external time variables is independent of a first phase of the first time, and

a second time of reception of the second external time variables is independent of a second phase of the second time.

21. The at least one storage medium of claim 19, wherein the adjusting the values of the one or more local time variables causes the local time value to shift closer to at least one of the first external time value or the second external time value.

22. The at least one storage medium of claim 19, wherein the instructions are configured, when executed on the machine, to cause the machine to:

transmit, from the local node, values of the one or more local time variables,

wherein another external node of a set of external nodes is configured to;

receive the values of the one or more local time variables; and

adjust values of one or more other external time variables of the other external node based at least upon the values of the one or more local time variables, wherein the values of the one or more other external time variables are indicative of another external time value of the other external time node.

23. The at least one storage medium of claim 19, wherein:

the local time variables indicate a state of a local logical oscillator designed to define the local time value,

the first external time variables indicate a state of a first external logical oscillator designed to define the first external time value, and

the second external time variables indicate a state of a second external logical oscillator designed to define the second external time value.

24. The at least one storage medium of claim 17, wherein the instructions are configured, when executed on the machine, to cause the machine to:

determine a first trustworthiness of the first external node and a second trustworthiness of the second external node; and

adjust the values of the one or more local time variables based upon the first trustworthiness and the second trustworthiness.

25. The at least one storage medium of claim 17, wherein:

a first act of transmitting the first external time variables by the first external node is independent of the first external time value, and

a second act of transmitting the second external time variables by the second external node is independent of the second external time value.