Pulsed beacon-based interference reduction mechanism for wireless communication networks

• US 6,377,608 B1
• Filed: 09/30/1998
• Issued: 04/23/2002
• Est. Priority Date: 09/30/1998
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: Zyren, James G.
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/163,802
• Time in Patent Office: 1,301 Days
• Field of Search: 375/130, 375/132, 375/140, 375/141, 375/220, 370/320, 370/335, 370/342, 370/441, 370/479, 455/403, 455/418, 455/434, 455/440, 455/456, 455/462, 455/556, 455/515, 455/501, 455/524, 455/63, 455/67.3
• US Class Current: 375/132
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A repetitively pulsed beacon based mechanism prevents interference between wireless communication devices of users of a band wireless local area network WLAN, and wireless communication devices of ad hoc networks using the same ISM band. A beacon generator is installed in the vicinity of an access point of the WLAN infrastructure, and generates a wireless beacon in a portion of the ISM band that does not overlap that portion used by the WLAN. A beacon responsive radio control mechanism, installed in each ad hoc radio, monitors the beacon channel for the presence of the wireless beacon. In response to detecting the beacon, the radio control mechanism adjusts the operation of its ad hoc radio, to avoid simultaneous use of the same portion of the ISM band as the WLAN. In one example, the ad hoc radio is adjusted so that it transmits within a selected portion of the ISM band other than that used by the WLAN.

Claims

1. For use with a communication network having a wireless access point through which wireless connectivity is available for users of said communication network within a first portion of a prescribed band of the wireless communication spectrum, a method of preventing interference between first wireless communication devices of said users of said communication network and second wireless communication devices of others than said users of said communication network, who are capable of transmitting within said first portion of said prescribed band of said wireless communication spectrum, said method comprising the steps of:

(a) at a location in the vicinity of said wireless access point, generating a wireless beacon in a second portion of said prescribed band of said wireless communication spectrum that does not overlap said first portion of said prescribed band of said wireless communication spectrum;

(b) at a second wireless communication device, monitoring said second portion of said prescribed band of said wireless communication spectrum for the presence of said wireless beacon; and

(c) in response to detecting said wireless beacon, causing said second wireless communication device to avoid use of said first portion of said prescribed band of said wireless communication spectrum.

2. A method according to claim 1, wherein step (c) comprises, in response to detecting said wireless beacon, causing said second wireless communication device to transmit within a selected portion of said prescribed band of said wireless communication spectrum other than said first and second portions of said prescribed band of said wireless communication spectrum.

3. A method according to claim 1, wherein connectivity between said users of said communication network and said wireless access point is provided within a first subportion of said first portion of said prescribed band of said wireless communication spectrum, and wherein step (c) comprises, in response to detecting said wireless beacon, causing said second wireless communication device to transmit within a second subportion of said first portion of said prescribed band of said wireless communication spectrum that does not overlap said first subportion of said first and second portions of said prescribed band of said wireless communication spectrum.

4. A method according to claim 3, wherein said first subportion of said second portion of said prescribed band of said wireless communication spectrum has bandwidth smaller than bandwidth of said first subportion of said first portion of said prescribed band of said wireless communication spectrum.

5. A method according to claim 1, wherein step (c) comprises causing said second wireless communication device to conduct frequency hop communications within said selected portion of said prescribed band of said wireless communication spectrum other than said first portion of said prescribed band of said wireless communication spectrum.

6. A method according to claim 1, wherein said wireless connectivity is available for users of said communication network within the entirety of said first portion of a prescribed band of the said communication spectrum, and wherein step (c) comprises, in response to detecting said wireless beacon, causing said second wireless communication device to transmit within a portion of said prescribed band of said wireless communication spectrum exclusive of said first and second portions of said prescribed band of said wireless communication spectrum.

7. A method according to claim 6, wherein step (c) comprises causing said second wireless communication device to transmit at a fixed frequency channel within said prescribed band of said wireless communication spectrum.

8. A method according to claim 1, wherein said prescribed band of the wireless communication spectrum comprises the unlicensed industrial, scientific and medical (ISM) band.

9. A method according to claim 1, wherein said second portion is above said first portion of said prescribed band.

10. A method according to claim 1, wherein said second portion is below said first portion of said prescribed band.

11. A method according to claim 1, wherein step (a) comprises intermittently transmitting a pulsed wireless beacon in said second portion of said prescribed band of said wireless communication spectrum.

12. A method according to claim 11, wherein step (a) comprises periodically transmitting said pulsed wireless beacon at a fixed frequency in said second portion of said prescribed band of said wireless communication spectrum.

13. A method according to claim 11, wherein said pulsed wireless beacon transmitted in step (a) has a prescribed amplitude and a duration that results in an average power of said pulsed wireless beacon being no greater than 0 dBm.

14. A method according to claim 12, wherein said pulsed wireless beacon transmitted in step (a) has a peak power no larger than +20 dBm and a duty cycle that results in an average power no greater than 0 dBm.

15. A method according to claim 1, wherein said wireless beacon contains information representative of first frequency hop communications, within said first portion of said prescribed band of said wireless communication spectrum, through which said wireless connectivity with said communication network is provided by way of said wireless access point, and wherein step (c) comprises causing said second wireless communication device to conduct second frequency hop communications within said prescribed band of said wireless communication spectrum that avoids said first frequency hop communications.

16. A method according to claim 1, wherein step (b) comprises periodically monitoring said second portion of said prescribed band of said wireless communication spectrum for the presence of said wireless beacon.

17. A method according to claim 1, wherein step (b) comprises periodically tuning second wireless communication device to said second portion of said prescribed band of said wireless communication spectrum for a prescribed dwell interval.

18. A method according to claim 1, wherein step (a) comprises repetitively transmitting said pulsed wireless beacon at a first frequency, and wherein step (b) comprises periodically tuning said second wireless communication device to said first frequency, at a second frequency lower than said first frequency, and for a dwell interval that spans the period of said first frequency.

19. A method according to claim 1, wherein

step (a) comprises generating a further wireless beacon in a third portion of said prescribed band of said wireless communication spectrum that does not overlap said first portion of said prescribed band of said wireless communication spectrum,

step (b) comprises at a second wireless communication device, monitoring said third portion of said prescribed band of said wireless communication spectrum for the presence of said further wireless beacon, and

step (c) comprises, in response to detecting either wireless beacon, causing said second wireless communication device to avoid use of said first portion of said prescribed band of said wireless communication spectrum.

20. A method according to claim 19, wherein said second portion of said prescribed band is above said first portion of said prescribed band, and said third portion of said prescribed band is below said first portion of said prescribed band.

21. A method according to claim 1, wherein step (c) comprises, in response to detecting said wireless beacon, preventing said second wireless communication device from transmitting.

22. A method according to claim 1, wherein step (c) comprises, in response to detecting said wireless beacon, reducing transmit power of said second wireless communication device.

23. A method according to claim 1, wherein said second wireless communication device is operative to conduct frequency hopped spread spectrum communications with another wireless communication device.

24. A method according to claim 1, wherein said first wireless communication device is operative to conduct direct sequence spread spectrum communications with said access point.

25. A system for preventing interference between first wireless communication devices of users of a communication network, which has a wireless access point through which wireless connectivity is available for said users of said communication network within a first portion of a prescribed band of the wireless communication spectrum, and second wireless communication devices of others than said users of said communication network, who are capable of transmitting within said first portion of said prescribed band of said wireless communication spectrum, said system comprising:

a wireless beacon generator installed in the vicinity of said wireless access point, and being operative to generate a wireless beacon in a second portion of said prescribed band of said wireless communication spectrum that does not overlap said first portion of said prescribed band of said wireless communication spectrum; and

a beacon responsive mechanism installed in said second wireless communication device, and being operative to monitor said second portion of said prescribed band of said wireless communication spectrum for the presence of said wireless beacon and, in response to detecting said wireless beacon, being operative to control the operation of said second wireless communication device so as to avoid use of said first and second portions of said prescribed band of said wireless communication spectrum.

26. A system according to claim 25, wherein said beacon responsive mechanism is operative, in response to detecting said wireless beacon, to cause said second wireless communication device to transmit within a selected portion of said prescribed band of said wireless communication spectrum other than said first and second portions of said prescribed band of said wireless communication spectrum.

27. A system according to claim 25, wherein connectivity between said users of said communication network and said wireless access point is provided within a first subportion of said first portion of said prescribed band of said wireless communication spectrum, and wherein said beacon responsive mechanism is operative, in response to detecting said wireless beacon, to cause said second wireless communication device to transmit within a second subportion of said first portion of said prescribed band of said wireless communication spectrum that does not overlap said first subportion of said first portion of said prescribed band of said wireless communication spectrum.

28. A system according to claim 27, wherein said second subportion of said first portion of said prescribed band of said wireless communication spectrum has bandwidth smaller than bandwidth of said first subportion of said first portion of said prescribed band of said wireless communication spectrum.

29. A system according to claim 25, wherein said beacon responsive mechanism is operative to cause said second wireless communication device to conduct frequency hop communications within said selected portion of said prescribed band of said wireless communication spectrum other than said first portion of said prescribed band of said wireless communication spectrum.

30. A system according to claim 25, wherein said wireless connectivity is available for users of said communication network within the entirety of said first portion of a prescribed band of the said communication spectrum, and wherein said beacon responsive mechanism is operative, in response to detecting said wireless beacon, to cause said second wireless communication device to transmit within a second portion of said prescribed band of said wireless communication spectrum exclusive of said first portion of said prescribed band of said wireless communication spectrum.

31. A system according to claim 30, wherein said beacon responsive mechanism is operative to cause said second wireless communication device to transmit at a fixed frequency channel within said second portion of said prescribed band of said wireless communication spectrum.

32. A system according to claim 25, wherein said prescribed band of the wireless communication spectrum comprises the unlicensed industrial, scientific and medical (ISM) band.

33. A system according to claim 25, wherein said wireless beacon generator is operative to intermittently transmit a pulsed wireless beacon in said second portion of said prescribed band of said wireless communication spectrum.

34. A system according to claim 33, wherein said wireless beacon generator is operative to periodically transmit said pulsed wireless beacon at a fixed frequency in said second portion of said prescribed band of said wireless communication spectrum.

35. A system according to claim 25, wherein said wireless beacon contains information representative of first frequency hop communications, within said first portion of said prescribed band of said wireless communication spectrum, through which said wireless connectivity with said communication network is provided by way of said wireless access point, and wherein said beacon responsive mechanism is operative to cause said second wireless communication device to conduct second frequency hop communications within said prescribed band of said wireless communication spectrum that avoids said first frequency hop communications.

36. A system according to claim 25, wherein said beacon responsive mechanism is operative to periodically monitor said second portion of said prescribed band of said wireless communication spectrum for the presence of said wireless beacon.

37. A system according to claim 25, wherein said beacon responsive mechanism is operative to periodically tune second wireless communication device to said second portion of said prescribed band of said wireless communication spectrum for a prescribed dwell interval.

38. A system according to claim 25, wherein said wireless beacon generator installed is operative to repetitively transmit said pulsed wireless beacon at a first frequency, and wherein said beacon responsive mechanism is operative to periodically tune said second wireless communication device to said first frequency, at a second frequency lower than said first frequency, and for a dwell interval that spans the period of said first frequency.

39. A system according to claim 25, wherein said wireless beacon generator is operative to generate a further wireless beacon in a third portion of said prescribed band of said wireless communication spectrum that does not overlap said first portion of said prescribed band of said wireless communication spectrum, and said beacon responsive mechanism is operative to monitor said third portion of said prescribed band of said wireless communication spectrum for the presence of said further wireless beacon and, in response to detecting either wireless beacon, to cause said second wireless communication device to avoid use of said first portion of said prescribed band of said wireless communication spectrum.

40. A system according to claim 39, wherein said second portion of said prescribed band is above said first portion of said prescribed band, and said third portion of said prescribed band is below said first portion of said prescribed band.

41. A system according to claim 25, wherein said beacon responsive mechanism is operative to inhibit said second wireless communication device from transmitting in response to detecting said wireless beacon.

42. A system according to claim 25, wherein said beacon responsive mechanism is operative to reduce transmit power of said second wireless communication device in response to detecting said wireless beacon.

43. A system according to claim 25, wherein said second wireless communication device is operative to conduct frequency hopped spread spectrum communications with another wireless communication device.

44. A system according to claim 25, wherein said first wireless communication device is operative to conduct direct sequence spread spectrum communications with said access point.