Method and apparatus for synchronizing time of day of terminal in convergent network

• US 8,397,095 B2
• Filed: 10/07/2009
• Issued: 03/12/2013
• Est. Priority Date: 10/08/2008
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Park, Dae Geun, Lee, Jung Hee, Lee, Seung Woo, Lee, Bhum Cheol
• Primary Examiner(s): Vo, Tim T
• Assistant Examiner(s): Cerullo, Jeremy S
• Application Number:
  US12/575,375
• Publication Number:
  US 20100086091A1
• Time in Patent Office: 1,252 Days
• Field of Search: 713/400, 713/401
• US Class Current: 713/400
• CPC Class Codes: G04R 20/18 Decoding time data; Circuits therefor
• CPC Class Codes: 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
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

Provided is a method and apparatus for synchronizing a time of day (TOD) in a convergent network, wherein the TOD is received from a time server connected in the convergent network and is provided to a terminal connected in a wired or wireless network, specifically a terminal connected in a heterogeneous network, that requires TOD information. The apparatus includes a time server that provides standard TOD information, a gateway or a host personal computer (PC) that provides the standard TOD information of the time server to the terminal in a 3rd layer or lower instead of an upper layer of the open system interconnection (OSI) 7 layer model, and the terminal that adjusts a local clock according to the provided standard TOD information. According to the method and apparatus, the terminal not only maintains a very precise TOD by obtaining TOD information of the time server periodically or when required, but also obtains the TOD information without using application software for processing the TOD information. Accordingly, power consumption of the terminal is decreased.

Claims

1. A method of synchronizing a time of day (TOD) of a terminal in a convergent network, the method comprising:

registering and storing identification information and TOD information of a terminal;

obtaining a first path delay time caused by a TOD synchronization message transmission path between the terminal and a TOD synchronization adjusting and storage unit that adjusts TOD synchronization of the terminal, and registers and stores the identification information and the TOD information;

obtaining a second path delay time caused by a TOD synchronization message transmission path between the TOD synchronization adjusting and storage unit and a time server providing a standard time;

obtaining delay compensated TOD information by applying the first path delay time and the second path delay time to the standard time;

converting the delay compensated TOD information to a form of TOD information of the terminal; and

transmitting the converted delay compensated TOD information to the terminal,

wherein when a plurality of terminals are connected to the TOD synchronization adjusting and storage unit, selecting one of the plurality of terminals, and multicasting and transmitting the delay compensated TOD information to the plurality of terminals.

2. The method of claim 1, wherein in the transmitting of the converted delay compensated TOD information, the converted delay compensated TOD information is transmitted from the TOD synchronization adjusting and storage unit to the terminal in a 3rd layer or lower in an open system interconnection (OSI) 7 layer model.

3. The method of claim 1, wherein the TOD synchronization adjusting and storage unit is a gateway or a host personal computer (PC).

4. The method of claim 1, wherein the time server and the TOD synchronization adjusting and storage unit transmit and receive a TOD synchronization message by using a network time protocol (NTP) or a precision timing protocol (PTP).

5. The method of claim 1, wherein in the converting of the delay compensated TOD information, the converting of the delay compensated TOD information according to a form of the registered and stored TOD information is limited to a terminal that is registered and stored in the TOD synchronization adjusting and storage unit.

6. The method of claim 1, wherein in the obtaining of the first path delay time, the first path delay time is measured periodically or when required.

7. The method of claim 1, wherein a network connecting the time server and the TOD synchronization adjusting and storage unit, and a network connecting the TOD synchronization adjusting and storage unit and the terminal are a heterogeneous network.

8. The method of claim 1, wherein in the multicasting and transmitting of the delay compensated TOD information, a period of multicasting the delay compensated TOD information is identical to a period of obtaining the first path delay time.

9. The method of claim 1, wherein the at least one of the plurality of terminals is a wireless terminal.

10. An apparatus for synchronizing a TOD of a terminal in a convergent network, the apparatus comprising:

a receiver that receives standard TOD information from a time server; and

a TOD synchronization adjusting and storage unit that registers and stores identification information and TOD information of a terminal, and transmits delay compensated TOD information in a form of the TOD information of the terminal by applying a delay time caused by a TOD synchronization message transmission path between the time server and the terminal to the standard TOD.

11. The apparatus of claim 10, wherein, when a plurality of terminals are connected to the TOD synchronization adjusting and storage unit, the TOD synchronization adjusting and storage unit selects one of the plurality of terminals, registers and stores identification information and TOD information of the plurality of terminals, stores delay compensated TOD information in a form of the TOD information of the selected terminal by applying a delay time caused by a TOD synchronization message transmission path between the time server and the selected terminal on the standard TOD, and multicasting and transmitting the delay compensated TOD information to the plurality of terminals.

12. The apparatus of claim 11, wherein a period of the TOD synchronization adjusting and storage unit multicasting the delay compensated TOD information is identical to a period of measuring the delay time.

13. The apparatus of claim 11, wherein at least one of the plurality of terminals is a wireless terminal.

14. The apparatus of claim 10, wherein the delay time caused by the TOD synchronization message transmission path between the time server and the terminal comprises a first path delay time caused by a TOD synchronization message transmission path between the TOD synchronization adjusting and storage unit and the terminal, and a second path delay time caused by a TOD synchronization message transmission path between the time server and the TOD synchronization adjusting and storage unit.

15. The apparatus of claim 10, wherein the TOD synchronization adjusting and storage unit transmits the delay compensated TOD information from the TOD synchronization adjusting and storage unit to the terminal in a 3rd layer or lower in an open system interconnection (OSI) 7 layer model.

16. The apparatus of claim 10, wherein the TOD synchronization adjusting and storage unit is a gateway or a host personal computer (PC).

17. The apparatus of claim 10, wherein the time server and the TOD synchronization adjusting and storage unit transmit and receive a TOD synchronization message by using a network time protocol (NTP) or a precision timing protocol (PTP).

18. The apparatus of claim 10, wherein the delay time caused by the TOD synchronization message transmission path between the time server and the terminal is measured periodically.

19. The apparatus of claim 10, wherein a network connecting the time server and the TOD synchronization adjusting and storage unit, and a network connecting the TOD synchronization adjusting and storage unit and the terminal are a heterogeneous network.