System and method for remote clock estimation for reliable communications
An electronic device is provided including a processor, a communications interface coupled to the processor, a memory coupled to the processor, and a module saved in the memory. The module configures the processor to receive a first communications packet from a remote device via the communications interface including information useful for estimating a clock offset of the remote device, and determine an upper bound of the clock offset of the remote device with respect to the electronic device based on the information.
1. An electronic device comprising:
a processor; and
a communications interface coupled to the processor;
the processor being configured to:
receive a first communications packet from a remote device via the communications interface, the first communications packet being received over a wireless communication link and including information useful for estimating a clock offset of the remote device;
determine an upper bound of the clock offset of the remote device with respect to the electronic device based on the information; and
determine a maximum age of data contained in the first communications packet based on the upper bound of the clock offset of the remote device with respect to the electronic device.
2. The electronic device according to claim 1 , wherein the information useful for estimating the clock offset of the remote device includes a timestamp of the electronic device at a start of transmission of a second communications packet to the remote device, T1, a timestamp of the remote device upon receipt of the second communications packet, T2, and a timestamp of the remote device at a start of transmission of the first communications packet, T3.
3. The electronic device according to claim 2 , wherein the information useful for estimating the clock offset of the remote device further includes a timestamp of the electronic device upon receipt of the first communications packet, T4.
4. The electronic device according to claim 2 , wherein the second communications packet was sent earlier in time than the first communications packet and the communications packets are TCP/IP packets that are not explicit request/response packets sent for the purpose of determining timing information.
5. The electronic device according to claim 2 , wherein the second communications packet is received over a wired link, a wireless link or a combination thereof.
6. The electronic device according to claim 1 , wherein the remote device is located at a remote location away from the electronic device.
7. The electronic device according to claim 1 , wherein the first communications packet is sent over the Internet.
8. The electronic device according to claim 1 , wherein the first communications packet includes data for controlling a robotic arm remotely by the remote device.
9. A method of determining an upper bound of a clock offset of a remote device relative to an electronic device, the method comprising:
receiving a first communications packet from the remote device via the communications interface, the first communications packet being received over a wireless communication link and including information useful for estimating a clock offset of the remote device;
determining the upper bound of the clock offset of the remote device with respect to the electronic device based on the information; and
determining a maximum age of data contained in the first communications packet based on the upper bound of the clock offset of the remote device with respect to the electronic device.
10. The method according to claim 9 , wherein the information useful for estimating the clock offset of the remote device includes a timestamp of the electronic device at a start of transmission of a second communications packet to the remote device, T1, a timestamp of the remote device upon receipt of the second communications packet, T2, and timestamp of the remote device at a start of transmission of the first communications packet, T3.
11. The method according to claim 10 , wherein the information useful for estimating the clock offset of the remote device further includes a timestamp of the electronic device upon receipt of the first communications packet, T4.
12. The method according to claim 10 , wherein the second communications packet was sent earlier in time than the first communications packet and the communications packets are TCP/IP packets that are not explicit request/response packets sent for the purpose of determining timing information.
13. The method according to claim 10 , wherein the second communications packet is received over a wired link, a wireless link or a combination thereof.
14. The method according to claim 9 , wherein the remote device is located at a remote location away from the electronic device.
15. The method according to claim 9 , wherein the first communications packet is sent over the Internet.
16. The method according to claim 9 , wherein the first communications packet includes data for controlling a robotic arm remotely by the remote device.
17. A navigation system for controlling a robotic arm, the navigation system comprising:
a first processor, and a first communications interface coupled to the first processor; and
a robotic arm having a second processor coupled to a second memory, and a second communications interface for wireless communication with the first communications interface;
wherein the robotic arm is located remotely from the first processor;
at least one of the first or second processor being configured to:
receive a first communications packet from a remote device via the corresponding communications interface, the first communications packet being received over a wireless communication link and including information useful for estimating a clock offset of the remote device, the remote device being the other of the first and second processor;
determine an upper bound of the clock offset of the remote device with respect to the processor performing the determination based on the information; and
determine a maximum age of data contained in the first communications packet based on the upper bound of the clock offset of the remote device with respect to the processor performing the determination.
18. The navigation system according to claim 17 , wherein the information useful for estimating the clock offset of the remote device includes a timestamp of the processor performing the determination at a start of transmission of a second communications packet to the remote device, T1, a timestamp of the remote device upon receipt of the second communications packet, T2, and a timestamp of the remote device at a start of transmission of the first communications packet, T3.
19. The navigation system according to claim 18 , wherein the information useful for estimating the clock offset of the remote device further includes a timestamp of the processor performing the determination upon receipt of the first communications packet, T4.
20. The navigation system according to claim 18 , wherein the second communications packet was sent earlier in time than the first communications packet and the communications packets are TCP/IP packets that are not explicit request/response packets sent for the purpose of determining timing information.
21. The navigation system according to claim 18 , wherein the second communications packet is received over a wired link, a wireless link or a combination thereof.
22. The navigation system according to claim 17 , wherein the first communications packet is sent over the Internet.