Method and apparatus for performing synchronization in device-to-device network

• US 9,332,513 B2
• Filed: 05/16/2013
• Issued: 05/03/2016
• Est. Priority Date: 05/16/2012
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Seung-Hoon, Kim, Kyung-Kyu, Kim, Dae-Gyun, Lim, Chi-Woo
• Primary Examiner(s): Wong, Xavier S.
• Application Number:
  US13/895,846
• Publication Number:
  US 20130308625A1
• Time in Patent Office: 1,083 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators
• CPC Class Codes: H04B 3/232 using phase shift, phase roll or frequency offset correction
• CPC Class Codes: H04J 3/0602 Systems characterised by the synchronising information used
• CPC Class Codes: H04J 3/0605 Special codes used as synchronising signal
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/002 Mutual synchronization

Abstract

A method and an apparatus for performing synchronization by a first device in a Device-to-Device (D2D) network are provided. The method includes detecting a synchronization signal from at least one second device during one period, determining a phase adjustment value depending on a number of synchronization signals, which have been detected from the at least one second device during the one period, adjusting a phase value of a first device using the phase adjustment value, and transmitting a synchronization signal if the phase value of the first device reaches a predetermined specific value.

Claims

1. A method for performing synchronization by a first device in a device-to-device (D2D) network, the method comprising:

detecting a synchronization signal from at least one second device during one period;

updating a coupling value based on a number of synchronization signals, which have been detected from the at least one second device during the one period;

adjusting a phase value based on the coupling value; and

transmitting a synchronization signal if the phase value reaches a predetermined value.

2. The method of claim 1, wherein the coupling value is updated by increasing a related value by a predetermined value if the number of synchronization signals is decreased by a predetermined range compared to a number of synchronization signals which is previously detected, or decreasing a related value by a predetermined value if the number of synchronization signals is increased by a predetermined range compared to a number of synchronization signals which is previously detected.

3. The method of claim 1, wherein the one period continues from a point of time that the first device transmitted a previous synchronization signal, until the first device transmits a current synchronization signal.

4. The method of claim 3, wherein the one period varies based on a number of synchronization signals, which have been detected from the at least one second device beginning from the point of time that the first device transmitted the previous synchronization signal, until the first device transmits the current synchronization signal.

5. The method of claim 1, wherein the coupling value includes a coupling factor used to adjust a phase of a pulse-coupled oscillator (PCO).

6. The method of claim 5, wherein the coupling factor is determined within a predetermined range between a minimum value and a maximum value, in inverse proportion to the number of synchronization signals.

7. The method of claim 6, further comprising counting the number of synchronization signals each time the first device detects a synchronization signal transmitted from another device.

8. The method of claim 7, wherein the coupling factor is determined in accordance with the following equation;

ε

=ε

_min+(ε

_max−

ε

_min)/(N_firings+1)

where ε

denotes the coupling factor, ε

_min denotes the minimum possible value of the coupling factor, ε

_max denotes the maximum possible value of the coupling factor, and N_firings denotes the number of synchronization signals.

9. The method of claim 6, further comprising counting the number of synchronization signals each time the first device detects a synchronization signal that is transmitted from other groups each including a plurality of devices that transmit a synchronization signal having the same timing.

10. The method of claim 9, wherein the coupling factor is determined in accordance with the following equation;

11. The method of claim 1, wherein the phase value is determined in accordance with the following equation;

g(Φ

)=ƒ

<sup>−

1</sup>(ƒ

(t))+ε

)

where g(Φ

) denotes the phase value, ε

denotes the coupling value, ƒ

denotes a predetermined function, and Φ

(t) denotes a phase value when the first device detects a synchronization signal.

23. The method of claim 1, wherein the coupling value includes a coupling factor used to adjust a phase of an oscillator, and

wherein the coupling factor is determined based on at least one of a minimum possible value of the coupling factor, a maximum possible value of the coupling factor, and the number of synchronization signals.

12. An apparatus for performing synchronization by a first device in a device-to-device (D2D) network, the apparatus comprising:

a receiver configured to detect a synchronization signal from at least one second device during one period; and

a controller processor configured to;

update a coupling value for adjusting a phase based on a number of synchronization signals, which have been detected from the at least one second device during the one period,

adjust a phase value based on the coupling value, and

control a transmitter to transmit a synchronization signal if the phase value reaches a predetermined value.

13. The apparatus of claim 12, wherein the coupling value is updated by increasing a related value by a predetermined value if the number of synchronization signals is decreased by a predetermined range compared to a number of synchronization signals which is previously detected, or decreasing a related value by a predetermined value if the number of synchronization signals is increased by a predetermined range compared to a number of synchronization signals which is previously detected.

14. The apparatus of claim 12, wherein the one period continues from a point of time that the first device transmitted a previous synchronization signal, until the first device transmits a current synchronization signal.

15. The apparatus of claim 14, wherein the one period varies based on a number of synchronization signals, which have been detected from the at least one second device beginning from the point of time that the first device transmitted the previous synchronization signal, until the first device transmits the current synchronization signal.

16. The apparatus of claim 12, wherein the coupling value includes a coupling factor used to adjust a phase of a pulse-coupled oscillator (PCO).

17. The apparatus of claim 16, wherein the coupling factor is determined within a predetermined range between a minimum value and a maximum value, in inverse proportion to the number of synchronization signals.

18. The apparatus of claim 17, wherein the controller processor counts the number of detected synchronization signals each time the first device detects a synchronization signal transmitted from another device.

19. The apparatus of claim 18, wherein the coupling factor is determined in accordance with the following equation;

ε

=ε

_min+(ε

_max−

ε

_min)/(N_firings+1)

where ε

denotes the coupling factor, ε

_min denotes the minimum possible value of the coupling factor, ε

_max denotes the maximum possible value of the coupling factor, and N_firings denotes the number of synchronization signals.

20. The apparatus of claim 17, wherein the controller processor counts the number of synchronization signals each time the first device detects a synchronization signal that is transmitted from other groups each including a plurality of devices that transmit a synchronization signal having the same timing.

21. The apparatus of claim 20, wherein the coupling factor is determined in accordance with the following equation;

22. The apparatus of claim 12, wherein the phase value of the first device is determined in accordance with the following equation;

g(Φ

)=ƒ

<sup>−

1</sup>(ƒ

(Φ

(t))+ε

)

where g(Φ

) denotes the phase value, ε

denotes the coupling value, f denotes a predetermined function, and Φ

(t) denotes a phase value when the first device detects the synchronization signal.

24. The apparatus of claim 12, wherein the coupling value includes a coupling factor used to adjust a phase of an oscillator, and

wherein the coupling factor is determined based on at least one of a minimum possible value of the coupling factor, a maximum possible value of the coupling factor, and the number of synchronization signals.