System and method for synchronizing wireless communication devices

• US 7,925,285 B2
• Filed: 01/19/2010
• Issued: 04/12/2011
• Est. Priority Date: 08/21/2001
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Indirabhai, Jyothis
• Primary Examiner(s): DOAN, PHUOC HUU
• Application Number:
  US12/689,628
• Publication Number:
  US 20100120458A1
• Time in Patent Office: 448 Days
• Field of Search: None
• US Class Current: 455/502
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

According to the present invention, Bluetooth master device offset information is determined and distributed among the master devices within a Bluetooth network. The system either provides an offset to each master device or determines master device offsets and distributes this information to master devices within the system to allow or efficient hand-offs of a slave between master devices.

Claims

1. A method for distributing timing information amongst a plurality of Bluetooth master devices, comprising:

transmitting a global clock to each master device of the plurality of master devices, wherein each master device comprises a Bluetooth master device and is a master of a respective piconet, wherein each master device of the plurality of master devices operates according to a respective and unique local clock that is independent of the global clock, wherein a slave device communicates with a first master device of the plurality of master devices by synchronizing with the respective local clock of the first master device, and wherein the slave device comprises a Bluetooth slave device;

determining, in each master device, a respective offset between the global clock and the respective local clock, wherein the respective offsets are different from each other; and

transmitting the respective offset of the first master device of the plurality of master devices to a second master device of the plurality of master devices to facilitate a handoff of the slave device from the first master device to the second master device.

2. The method according to claim 1, wherein the global clock comprises a local clock of one of the plurality of master devices.

3. The method according to claim 1, wherein the respective offset of the first master device is distributed over a communication pathway linking the first master device to the second master device.

4. The method according to claim 3, wherein the communication pathway comprises a wired communication pathway.

5. The method according to claim 3, wherein the communication pathway comprises a wireless communication pathway.

6. The method according to claim 1, wherein each master device transmits the respective offset to a central storage device, and wherein each master device can request, from the central storage device, the respective offsets of other master devices of the plurality of master devices.

7. The method according to claim 1, wherein the second master device requests the respective offset of the first master device, and wherein the first master device transmits the respective offset to the second master device.

8. The method according to claim 1, wherein each master device stores respective offsets of other master devices of the plurality of master devices to effect handoffs of slave devices.

9. The method according to claim 1, wherein the first master device comprises a first mobile phone configured to act as a first master in a first piconet, and wherein the second master device comprises one of a second mobile phone, a printer and a computer, the second master being configured to act as a second master in a second piconet.

10. The method according to claim 1, wherein each master device intermittently transmits the respective offset and intermittently receives the respective offsets of the other master devices of the plurality of master devices.

11. A method for distributing timing information amongst of a plurality of Bluetooth master devices, comprising:

transmitting a global clock to each master device of the plurality of master devices, wherein each master device comprises a Bluetooth master device and is a master of a respective piconet;

transmitting, to each master device, a respective and unique offset;

generating, in each master device, a respective local clock using the respective offset and the global clock, wherein the respective local clock is used by a first master device of the plurality of master devices to communicate with a slave device in the respective piconet of the first master device, and wherein the slave device comprises a Bluetooth slave device; and

transmitting the respective offset of the first master device to a second master device of the plurality of master devices to facilitate a wireless handoff of the slave device from the first master device to the second master device.

12. The method according to claim 11, wherein each of the master devices comprises a local oscillator, and wherein the global clock comprises a clock signal generated by the local oscillator associated with one of the plurality of master devices.

13. The method according to claim 11, wherein the respective offsets are stored in a central location and provided to at least two of the master devices.

14. The method according to claim 11, wherein the respective offset of the first master device is stored locally at the second master device.

15. The method according to claim 11, wherein the first master device comprises a first mobile phone configured to act as a first master in a first piconet, and wherein the second master device comprises one of a second mobile phone, a printer and a computer, the second master being configured to act as a second master in a second piconet.

16. The method according to claim 11, wherein the respective offsets of the plurality of master devices are predetermined and constant.

17. A communication system that uses Bluetooth communication, comprising:

a global clock transmitting, over a first communication pathway, a global clock signal to each master device of a plurality of master devices; and

each master device of the plurality of master devices comprising a respective local clock generator that generates a respective and unique local clock and a respective memory that stores a respective offset, wherein each master device determines the respective offset from the global clock and the respective local clock, wherein each master device comprises a Bluetooth master device and is a master of a respective piconet, wherein a first master device of the plurality of master devices transmits, over a second communication pathway, its respective offset to a second master device of the plurality of master devices to facilitate a wireless handoff of a slave device from the first master device in a first piconet to the second master device in a second piconet, wherein the slave device comprises a Bluetooth slave device, wherein the slave device is synchronized with the respective local clock of the first master device, and wherein the respective offset of the first master device is used by the second master device to communicate with the slave device.

18. The system according to claim 17, wherein the first communication pathway comprises a first wireless communication pathway, and wherein the second communication pathway comprises a second wireless communication pathway.

19. The system according to claim 17, wherein the respective offsets of the plurality of master devices are stored in a central offset storage device.

20. The system according to claim 17, wherein the global clock comprises one of the respective local clocks of the plurality of master devices.

21. The system according to claim 17, wherein the second master device requests the respective offset of the first master device, stores the respective offset of the first master device in the respective memory of the second master device, and uses the respective offset of the first master device to communicate with the slave device.

22. The system according to claim 17, wherein the respective offsets are distributed by a central offset storage device upon request by one of the master devices.

23. The system according to claim 17, wherein the respective memory of the second master device stores the respective offset of the first master device and the respective offsets of other master devices of the plurality of master devices.

24. The system according to claim 17, wherein the first master device comprises a first mobile phone configured to act as a first master in the first piconet, and wherein the second master device comprises one of a second mobile phone, a printer and a computer, the second master being configured to act as a second master in the second piconet.

25. The system according to claim 17, wherein each master device intermittently posts the respective offset on the second communication pathway, and wherein each master device intermittently receives, via the second communication pathway, the respective offsets of the other master devices of the plurality of master devices.

26. A communication system that uses Bluetooth communication, comprising:

a global clock that transmits, over a first communication pathway, a global clock signal to each master device of a plurality of master devices, wherein each master device comprises a Bluetooth master device and is a master of a respective piconet; and

an offset control that transmits, over a second communication pathway, a respective and unique offset signal to each master device, wherein each master device comprises a respective local clock generator that generates a respective local clock signal as a function of the respective offset signal and the global clock signal, wherein the respective local clock signal of a first master device of the plurality of master devices is used by the first master device to synchronize communication with a slave device, wherein the slave device comprises a Bluetooth slave device, and wherein the respective offset signal of the first master device is transmitted to a second master device of the plurality of master devices to facilitate a wireless handoff of the slave device from the first master device in a first piconet to the second master device in a second piconet.

27. The system according to claim 26, wherein the first communication pathway comprises a first wired communication pathway, and wherein the second communication pathway comprises a second wired communication pathway.

28. The system according to claim 26, wherein the first communication pathway comprises a first wireless communication pathway, and wherein the second communication pathway comprises a second wireless communication pathway.

29. The system according to claim 26, wherein the global clock generates a single global clock signal that is used by each master device, and wherein the single global clock signal is generated by one of the clock generators of the plurality of master devices.

30. The system of claim 26, further comprising a memory that is operatively coupled to the second communication pathway, wherein the offsets are stored in the memory.

31. The system according to claim 26, wherein each master device receives the respective offset for each of the other master devices.

32. The system according to claim 26, wherein each of the master devices comprises a local memory for storing offsets associated with at least one of the master devices.

33. The system according to claim 26, wherein the first master device comprises a first mobile phone configured to act as a first master in the first piconet, and wherein the second master device comprises one of a second mobile phone, a printer and a computer, the second master being configured to act as a second master in the second piconet.

34. The system according to claim 26, wherein the first communication pathway comprises a bus that is operatively coupled to a first card and to a second card, wherein the first master device is part of the first card, and wherein the second master device is part of the second card.