Reduced subset scan and dual frequency wakeup for bluetooth inquiry operation

• US 7,184,458 B2
• Filed: 09/12/2001
• Issued: 02/27/2007
• Est. Priority Date: 02/20/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Dabak, Anand G., Schmidl, Timothy M.
• Primary Examiner(s): Bayard; Emmanuel
• Assistant Examiner(s): Williams; Lawrence B.
• Application Number:
  US09/953,533
• Publication Number:
  US 20020114377A1
• Time in Patent Office: 1,994 Days
• Field of Search: 375/132, 375/133, 375/281, 375/322, 375/345, 370/255, 370/331, 370/338, 370/449, 455/41.1, 455/62, 455/63, 455/436, 455/437, 455/444, 455/452, 455/522, 455/154, 455/450, 455/455, 455/434
• US Class Current: 375/132
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

An inquiry message is transmitted successively on each of a first plurality of transmit frequencies (44–48) and thereafter successively on each of a second plurality of transmit frequencies (51), in order to ensure that a first wireless communication apparatus that listens on one of the transmit frequencies will receive the inquiry message. The first plurality of transmit frequencies can also be ensured (25–28) to include a frequency on which a second wireless communication apparatus is listening for the inquiry message. With respect to reception of an inquiry message that is transmitted successively on each of first and thereafter second pluralities of transmit frequencies, after receipt (61) of the initial inquiry message and subsequent expiration of a corresponding backoff period (62), the inquiry message is first listened for on a first frequency of the first plurality of transmit frequencies for a predetermined time (63). If the inquiry message is not received on the first frequency during the first listening operation, the inquiry message is then listened for on a second frequency of the second plurality of transmit frequencies for a predetermined time (64).

Claims

1. A wireless communication apparatus, comprising:

a wireless communication interface for transmitting an inquiry message over a wireless communication channel;

a controller arranged to produce a select signal corresponding to one of a first and second plurality of frequencies, the select signal initially corresponding to the first plurality of frequencies for every inquiry message; and

a frequency selection apparatus coupled to said wireless communication interface for controlling said wireless communication interface to transmit the inquiry message successively an each of the first plurality of frequencies and thereafter successively on each of the second plurality of frequencies in response to the select signal.

2. The apparatus of claim 1, wherein said frequency selection apparatus includes a first selector for selectively providing one of first and second parameters respectively associated with said first and second pluralities of frequencies in response to the select signal.

3. The apparatus of claim 2, wherein said frequency selection apparatus includes a clack for producing a clock signal, and a storage apparatus coupled to said clock for storing said clock signal.

4. The apparatus of claim 3, wherein said storage apparatus includes an input for receiving a signal indicative of a point in time at which said storage apparatus is to store said clock signal.

5. The apparatus of claim 3 wherein said frequency selection apparatus includes a combiner coupled to said storage apparatus and said first selector for combining one of said first and second parameters with said stored clock signal to produce result information.

6. The apparatus of claim 5, wherein said combiner is an arithmetic combiner.

7. The apparatus of claim 5, wherein said frequency selection apparatus includes a frequency selector coupled to said wireless communication interface for selecting frequencies and indicating the selected frequencies to said wireless communication interface, said frequency selection apparatus further including a frequency selector input generator coupled to said combiner and said frequency selector and responsive to said result information for producing an input signal for said frequency selector, said frequency selector responsive to said input signal for selecting frequencies.

8. The apparatus of claim 7, wherein said frequency selector input generator is also coupled to said clock and is further responsive to said clock signal for producing said frequency selector input signal.

9. The apparatus of claim 3, wherein said clock signal includes a plurality of digital bits and said storage apparatus is a latch.

10. The apparatus of claim 1, provided as a Bluetooth device.

11. A method of wireless communication, comprising:

entering an inquiry state for producing an inquiry message on a first and a second plurality of frequencies;

selecting the first plurality of frequencies for every initial inquiry message after the step of entering;

selecting the second plurality of frequencies for a subsequent inquiry message; and

transmitting the inquiry message successively on each of the first plurality of frequencies and thereafter successively on each of the second plurality of frequencies.

12. The method of claim 11, including selectively providing one of first and second parameters respectively associated with said first and second pluralities of frequencies.

13. The method of claim 12, including providing a clock signal, and storing said clock signal at a desired point in time.

14. The method of claim 13, including combining one of said first and second parameters with said stored clock signal to produce result information.

15. The method of claim 14, wherein said combining step includes arithmetically combining one of said first and second parameters with said stored clock signal.

16. The method of claim 14, including selecting frequencies in response to said result information.

17. The method of claim 16, wherein said selecting step includes selecting frequencies also in response to said clock signal.

18. The method of claim 13, wherein said storing step includes storing said clock signal at a selected point in time.

19. The method of claim 18, wherein said clock signal includes a plurality of digital bits and said storing step includes latching said clock signal.

20. The method of claim 11, wherein said inquiry message is a Bluetooth inquiry message.

21. A method of receiving an inquiry message transmitted successively on each of a first plurality of wireless communication frequencies and thereafter successively on each of a second plurality of wireless communication frequencies, comprising:

initially receiving the inquiry message, and thereafter waiting until expiration of a backoff period of time;

first listening for said inquiry message for a predetermined time on a first frequency of said first plurality of frequencies in response to expiration of said backoff period; and

second listening for said inquiry message for a predetermined time on a second frequency of the second plurality of frequencies if said inquiry message is not received on said first frequency during said first listening step.

22. The method of claim 21, including, if the inquiry message is not received on said second frequency during said second listening step, repeating said first listening step.

23. The method of claim 22, including alternatingly performing said first and second listening steps until the inquiry message is received or a timeout occurs.

24. The method of claim 21, including selecting a length of said backoff period randomly.

25. The method of claim 21, including, if said inquiry message is received during either of said listening steps, repeating said waiting step and thereafter alternatingly performing said first and second listening steps on third and fourth frequencies, respectively, starting with said first listening step;

and

said third and fourth frequencies contained respectively within said first and second pluralities of frequencies if said inquiry message was received on said first frequency during said first listening step, and said third and fourth frequencies contained respectively within said second and first pluralities of frequencies if said inquiry message was received on said second frequency during said second listening step.

26. The method of claim 21, including providing a clock signal, and storing the clock signal at a selected point in time.

27. The method of claim 26, wherein the selected point in time corresponds to said initial receipt of said inquiry message.

28. The method of claim 27, including selecting said first and second frequencies in response to said stored clock signal.

29. The method of claim 26, including selecting the first and second frequencies in response to said stored clock signal.

30. The method of claim of 29, wherein said stored clock signal is a digital value, and wherein said step of selecting said first and second frequencies includes performing an arithmetic operation on said stored clock signal.

31. The method of claim 21, wherein the predetermined time associated with one of said first and second listening steps is significantly shorter than a total amount of time occupied by all of said transmissions on one of the first and second pluralities of frequencies.

32. The method of claim 21, wherein the predetermined times respectively associated with said first and second listening steps are equal to one another.

33. The method of claim 21, wherein said inquiry message is a Bluetooth inquiry message.

34. A wireless communication apparatus for receiving an inquiry message transmitted successively on each of a first plurality of wireless communication frequencies and thereafter successively on each of a second plurality of wireless communication frequencies, comprising:

a wireless communication interface far initially receiving the inquiry message;

a controller coupled to said wireless communication interface and responsive to initial receipt of the inquiry message for implementing a backoff time period;

a frequency selection apparatus coupled to said controller and said wireless communication interface and responsive to said controller after expiration of said backoff period for directing said wireless communication interface to first listen for said inquiry message for a predetermined time on a first frequency of said first plurality of frequencies; and

said frequency selection apparatus responsive to said controller if said inquiry message is not received on said first frequency during said first listening operation for directing said wireless communication interface to secondly listen for said inquiry message for a predetermined time on a second frequency of said second plurality of frequencies.

35. The apparatus of claim 34, wherein said frequency selection apparatus is responsive to said controller if the inquiry message is not received on said second frequency during said second listening operation for directing said wireless communication interface to repeat said first listening operation.

36. The apparatus of claim 35, wherein said frequency selection apparatus is responsive to said controller for directing said wireless communication interface to perform alternatingly said first and second listening operations until the inquiry message is received or said controller detects a dine out.

37. The apparatus of claim 34, wherein said controller is operable for selecting a length of said backoff period randomly.

38. The apparatus of claim 34, wherein said controller is operable in response to receipt of the inquiry message during either of said listening operations for again implementing a backoff period, said frequency selection apparatus responsive to said controller after expiration of said last-mentioned backoff period for directing said wireless communication interface to perform alternatingly said first and second listening operations on third and fourth frequencies, respectively, starting with said first listening operation;

and

said third and fourth frequencies respectively contained within said first and second pluralities of frequencies if said inquiry message was received on said first frequency during said first listening operation, and said third arid fourth frequencies respectively contained within said second and first pluralities of frequencies if said inquiry message was received on said second frequency during said second listening operation.

39. The apparatus of claim 34, including a clock for providing a clock signal, said frequency selection apparatus including a storage apparatus coupled to said clock and said controller for storing said clock signal at a point in time designated by said controller.

40. The apparatus of claim 39, wherein said storage apparatus includes a latch.

41. The apparatus of claim 39, wherein said point in time corresponds to said initial receipt of said inquiry message.

42. The apparatus of claim 41, wherein said frequency selection apparatus is operable for selecting said first and second frequencies in response to said stored clock signal.

43. The apparatus of claim 39, wherein said frequency selection apparatus is operable for selecting said first and second frequencies in response to said stored clock signal.

44. The apparatus of claim 43, wherein said stored clock signal is a digital value, said frequency selection apparatus including a signal generator coupled to said storage apparatus for performing an arithmetic operation on said stored clock signal.

45. The apparatus of claim 44, wherein said frequency selection apparatus includes a signal selector having a control input coupled to said controller, having signal inputs respectively coupled to said storage apparatus and said signal generator, and having a signal output.

46. The apparatus of claim 45, wherein said frequency selection apparatus includes a frequency selector having an input coupled to said signal output of said signal selector and having an output coupled to said wireless communication interface, said frequency selector responsive to said signal output of said signal selector for selecting a frequency and indicating the selecting frequency to said wireless communication interface.

47. The apparatus of claim 34, provided as a Bluetooth device.

48. The apparatus of claim 34, wherein the predetermined time associated with one of said first and second listening operations is significantly shorter than a total amount of time occupied by all of said transmissions on one of the first and second pluralities of frequencies.

49. The apparatus of claim 34, wherein the predetermined times respectively associated with said first and second listening operations are equal to one another.