IP Library Granted Patent US 11,522,626
Granted Patent B2
US 11,522,626 · App. 16/838,784 · Granted Dec 6, 2022

Acquiring current time in a network

Inventors: Danu Tjahjono (Dublin, CA); Rafiq Shaikh (Santa Clara, CA); Ajay K. Dassu (San Jose, CA)
Assignee: Hitachi Energy Switzerland AG
H04J3/0667H04J3/0644H04L63/0823H04L69/28
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Quick Facts
Patent No.
US 11,522,626
App. No.
16/838,784
Granted
Dec 6, 2022
Kind
B2
Abstract

Exemplary of embodiments of the disclosure include a method which includes determining, by a first device, whether the first device has a current time and transmitting a request for the current time to a second device if the first device does not have the current time. The second device is in a local network. The method further includes receiving, by the first device, the current time from the second device, authenticating a certificate based on the current time received from the second device, and establishing a network connection to the local network based on the authenticated certificate.

Claims (47)

1. A method comprising:

determining, by a first device, whether the first device has a current time;

transmitting, by the first device, a request for the current time to a second device in a local network if the first device does not have the current time;

receiving, by the first device, the current time from the second device;

authenticating, by the first device, a certificate based on the current time received from the second device; and

establishing, by the first device, a network connection to the local network based on the authenticated certificate.

2. The method of claim 1 , wherein establishing, by the first device, the network connection to the local network based on the authenticated certificate comprises establishing the network connection through a third device in the local network.

3. The method of claim 2 , wherein the third device is the second device.

4. The method of claim 1 , further comprising:

connecting to a network time protocol (NTP) server through the local network; and

synchronizing the current time with the NTP server, the current time synchronized with the NTP server being more accurate than the current time received from the second device.

5. The method of claim 4 further comprising:

receiving a request for the current time from a fourth device; and

transmitting, to the fourth device, the current time synchronized with the NTP server.

6. The method of claim 1 further comprising:

receiving a request for the current time from a fourth device prior to receiving the current time from the second device; and

transmitting, to the fourth device, the current time received from the second device if the current time is received from the second device without a preset time period of receiving the request for the current time from the fourth device.

7. The method of claim 6 further comprising not sending, to the fourth device, the current time received from the second device if the current time is not received from the second device within the preset time period of receiving the request for the current time from the fourth device.

8. The method of claim 7 further comprising forwarding, by the first device, the request for the current time received from the fourth device.

9. The method of claim 1 , wherein:

transmitting the request for the current time comprises broadcasting the request for the current time in a probe request; and

receiving the current time from the second device comprises receiving the current time in a probe response.

10. The method of claim 1 , wherein determining whether the first device has a current time comprises:

comparing a calendar time of the first device with a sum of a boot-up calendar time of the first device and an elapsed time of the first device, wherein the elapsed time of the first device is an amount of time that has elapsed since the first device booted up; and

determining that the first device does not have the current time if the calendar time is equal to the sum of the boot-up calendar time of the first device and the elapsed time of the first device.

11. A method comprising:

receiving, by a first device, a current time from a second device prior to the first device establishing a network connection, the second device being connected to a local network;

authenticating, by the first device, a certificate based on the current time received from the second device;

establishing, by the first device, the network connection to the local network based on the authenticated certificate; and

connecting, by the first device, to a network time protocol (NTP) server through the network connection to the local network.

12. The method of claim 11 , wherein receiving, by the first device, the current time from the second device comprises receiving, by the first device, the current time from the second device without transmitting, by the first device, a request for the current time.

13. The method of claim 11 , wherein receiving the current time from the second device comprises receiving the current time in a broadcast from the second device.

14. The method of claim 11 , wherein receiving the current time from the second device comprises receiving the current time in a unicast from the second device.

15. An apparatus, comprising:

a processor configured to determine whether the apparatus has a current time;

a transmitter configured to transmit a request for the current time to another apparatus in a local network if the apparatus does not have the current time; and

a receiver configured to receive the current time from the another apparatus in the local network;

wherein the processor is further configured to:

authenticate a certificate based on the current time received from the another apparatus; and

establish a network connection to the local network based on the authenticated certificate.

16. The apparatus of claim 15 , wherein the processor is further configured to connect to a network time protocol (NTP) server through the local network.

17. The apparatus of claim 16 , wherein the processor is further configured to connect, in a different operating mode, to the NTP server without the authenticated certificate.

18. The apparatus of claim 16 , wherein the processor is further configured to synchronize the current time with the NTP server.

19. The apparatus of claim 15 , wherein the apparatus does not have global positioning service (GPS) capabilities.

20. The apparatus of claim 15 , wherein:

the request for the current time is broadcast in a probe request; and

the current time is received from the another apparatus in a probe response.

Assignments (4)
MERGER Recorded Nov 13, 2023
From: HITACHI ENERGY SWITZERLAND AG
To: HITACHI ENERGY LTD
Reel/Frame 065548/0905 →
CHANGE OF NAME Recorded Dec 31, 2021
From: ABB POWER GRIDS SWITZERLAND AG
To: HITACHI ENERGY SWITZERLAND AG
Reel/Frame 058601/0692 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 15, 2021
From: ABB SCHWEIZ AG
To: ABB POWER GRIDS SWITZERLAND AG
Reel/Frame 055589/0769 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Oct 1, 2020
From: TJAHJONO, DANU; SHAIKH, RAFIQ; DASSU, AJAY K.
To: ABB SCHWEIZ AG
Reel/Frame 053951/0173 →