Frequency hopping radio LAN system and frequency hopping control method

• US 6,275,518 B1
• Filed: 01/22/1996
• Issued: 08/14/2001
• Est. Priority Date: 01/27/1995
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takahashi, Yasuhiro, Matsui, Susumu, Kondou, Takeshi
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US08/589,650
• Time in Patent Office: 2,031 Days
• Field of Search: 342/450, 342/455, 342/456, 370/321, 370/322, 370/324, 370/331, 370/341, 370/343, 370/524, 375/132-135, 375/138, 455/31.2, 455/63, 455/436, 455/447, 455/450, 455/501-502
• US Class Current: 375/135
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 2001/7154 with means for preventing interference
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence

Abstract

A radio LAN system based on a frequency hopping control scheme in which a deviation between frequency hopping timing in a cell and frequency hopping timing in another cell is measured, and as the deviation increases close to such a degree that causes interference, a frequency hopping pattern currently used in the cell is replaced with another frequency hopping pattern, or the order on the frequency hopping pattern is changed to avoid interference between the cells.

Claims

1. A frequency hopping radio LAN system comprising:

a radio base station used in a first cell, said radio base station including;

means for detecting a deviation of a frequency hopping pattern used in the first cell from a frequency hopping pattern used in another cell, and

means for instructing a change of the frequency hopping pattern used in the first cell if the detection result indicates that said deviation is beyond a tolerable range; and

a radio terminal responsive to said instruction to use another specified frequency hopping pattern from predetermined hopping timing.

2. A radio LAN system according to claim 1, wherein said detecting means includes:

means for calculating an interval between the first cell and the other cell with respect to a predetermined hopping frequency; and

deviation amount determining means for determining whether a deviation is within or beyond the tolerable range from the value of the calculated interval.

3. A radio LAN system according to claim 2, wherein said interval calculating means includes:

first clock means operative in association with hopping timing of the other cell;

second clock means indicative of hopping timing of the first cell; and

means for calculating an interval between the hopping timing of the first cell and the hopping timing of the other cell.

4. A radio LAN system according to claim 2, wherein said deviation amount determining means includes:

means for comparing the calculated interval with a predetermined value; and

means for determining that the deviation is beyond the tolerable range if the comparison result indicates that said interval is equal to or less than said predetermined value.

5. A radio LAN system according to claim 1, wherein said instructing means includes means for previously transmitting change notice data indicative of changing timing a plurality of times.

6. A radio LAN system according to claim 1 further comprising first and second movable radio terminals.

7. A frequency hopping radio LAN system comprising:

a radio base station used in a first cell, said radio base station including;

means for detecting a deviation of a frequency hopping pattern used in the first cell from a frequency hopping pattern used in another cell, and

means for instructing a change in the order of the frequency hopping pattern used in the first cell if the detection result indicates that the deviation is beyond tolerable range; and

a radio terminal responsive to said instruction to select a hopping frequency from the changed frequency hopping pattern at the next hopping timing.

8. A radio LAN system according to claim 7, wherein said detecting means includes:

means for calculating an interval between the first cell and the other cell with respect to a predetermined hopping frequency; and

deviation amount determining means for determining whether a deviation is within or beyond the tolerable range from the value of the calculated interval.

9. A radio LAN system according to claim 8, wherein said interval calculating means includes:

first clock means operative in association with hopping timing of the other cell;

second clock means indicative of hopping timing of the first cell; and

means for calculating an interval between the hopping timing of the first cell and the hopping timing of the other cell.

10. A radio LAN system according to claim 9, wherein said instructing means includes:

phase determining means for detecting a change in said interval to determine whether the hopping timing of the first cell has a phase advanced or delayed with respect to the hopping timing of the other cell.

11. A radio LAN system according to claim 8, wherein said deviation amount determining means includes:

means for comparing the calculated interval with a predetermined value; and

means for determining that the deviation is beyond the tolerable range if the comparison result indicates that said interval is equal to or less than said predetermined value.

12. A radio LAN system according to claim 7, wherein said instructing means includes means for instructing to skip a next hopping frequency to hop to the next but one hopping frequency at the next hopping timing if the hopping timing of the other cell is delayed from the hopping timing of the first cell, and for instructing to repeat the same hopping frequency at the next hopping timing if the hopping timing of the other cell is advanced from the hopping timing of the first cell.

13. A radio LAN system according to claim 12, wherein said instructing means includes:

means for calculating an interval between the hopping timing of the first cell and the hopping timing of the other cell; and

phase determining means for detecting a change in said interval to determine whether the hopping timing of the first cell has a phase advanced or delayed with respect to the hopping timing of the other cell.

14. A radio LAN system according to claim 7, wherein said instructing means includes means for previously transmitting change notice data indicative of changing timing a plurality of times.

15. A radio LAN system according to claim 7 further comprising first and second movable radio terminals.

16. A frequency hopping radio LAN system comprising:

a radio base station used in a first cell, said radio base station including;

means for detecting whether at least part of a frequency hopping pattern used in the first cell matches with a frequency hopping pattern used in another cell, and

means for instructing a change of the frequency hopping pattern used in the first cell if the detection result indicates that a matching degree is beyond a tolerable range; and

a radio terminal responsive to said instruction to use another specified frequency hopping pattern from predetermined hopping timing.

17. A radio LAN system according to claim 16, wherein said detecting means includes means for counting a number of times a hopping signal of the other cell is received, and said instructing means includes means for instructing a change of the frequency pattern used in the first cell the counted number exceeds a predetermined value.

18. A radio LAN system according to claim 16, wherein said instructing means includes means for previously transmitting change notice data indicative of changing timing a plurality of times.

19. A radio LAN system according to claim 16 further comprising first and second movable radio terminals.

20. A frequency hopping radio LAN system comprising:

a radio base station used in a first cell, said radio base station including;

means for detecting whether at least part of a frequency hopping pattern used in the first cell matches with a frequency hopping pattern of another cell, and

means for instructing a change in the order of the frequency hopping pattern used in the first cell a result of the detection indicates that a matching degree is beyond a tolerable range; and

a radio terminal responsive to said instruction to select a hopping frequency from the changed frequency hopping pattern at the next hopping timing.

21. A radio LAN system according to claim 20, wherein said detecting means includes means for counting a number of times a hopping signal of the other cell is received, and said instructing means includes means for instructing a change in the order of the frequency hopping pattern if the counted number exceeds a predetermined value.

22. A radio LAN system according to claim 20, wherein said instructing means includes means for issuing an instruction to skip a next frequency to hop to the next but one hopping frequency at the next hopping timing.

23. A radio LAN system according to claim 20, wherein said instructing means includes means for issuing an instruction to repeat the same frequency at the next hopping timing.

24. A radio LAN system according to claim 20, wherein said instructing means includes means for previously transmitting change notice data indicative of changing timing a plurality of times.

25. A radio LAN system according to claim 20, further comprising first and second movable radio terminals.

26. A frequency hopping control method in a frequency hopping radio LAN system comprising the steps of:

detecting in a radio base station used in a first cell a deviation of a frequency hopping pattern used in the first cell from a frequency hopping pattern used in another cell;

instructing from said radio base station to a radio terminal capable of communicating with said radio base station to change the frequency hopping pattern used in the first cell if the detecting result indicates that said deviation is beyond a tolerable range; and

performing communications using another frequency hopping pattern specified by said instruction from predetermined hopping timing.

27. A frequency hopping control method according to claim 26, wherein said detecting step includes the steps of:

calculating an interval between hopping timing of the first cell and hopping timing of said another cell with respect to a predetermined hopping frequency; and

determining that said deviation is beyond the tolerable range when said interval is equal to or less than a predetermined value.

28. A frequency hopping control method according to claim 26, wherein said instructing step includes the step of previously transmitting change notice data indicative of changing timing a plurality of times.

29. A frequency hopping control method in a frequency hopping radio LAN system comprising the steps of:

detecting in a radio base station used in a first cell a deviation of a frequency hopping pattern used in the first cell covered by said radio LAN system from a frequency hopping pattern used in another cell;

instructing from said radio base station to a radio terminal capable of communicating with said radio base station to change the order of the frequency hopping pattern used in the first cell if the detection result indicates that said deviation is beyond a tolerable range; and

performing communications at a hopping frequency on the frequency hopping pattern which was changed as instructed from a predetermined hopping timing.

30. A frequency hopping control method according to claim 29, wherein said detecting step includes the steps of:

calculating an interval between hopping timing of the first cell and hopping timing of another cell with respect to a predetermined hopping frequency; and

determining that said deviation is beyond the tolerable range when said interval is equal to or less than a predetermined value.

31. A frequency hopping control method according to claim 29, wherein said instructing step includes the step of instructing to skip a next frequency to hop to the next but one hopping frequency at the next hopping timing if the hopping timing of the other cell is delayed from the hopping timing of the first cell, and to repeat the same frequency at the next hopping timing if the hopping timing of the other cell is advanced from the hopping timing of the first cell.

32. A frequency hopping control method according to claim 31, wherein said instructing step includes the steps of:

calculating an interval between the hopping timing of the first cell and the hopping timing of the other cell with respect to a predetermined hopping frequency; and

detecting a change in said interval to determine whether the hopping timing of the first cell has a phase advanced or delayed with respect to the hopping timing of said other cell.

33. A frequency hopping control method according to claim 29, wherein said instructing step includes the step of previously transmitting change notice data indicative of changing timing a plurality of times.

34. A frequency hopping control method in a frequency hopping radio LAN system comprising the steps of:

detecting in a radio base station used in a first cell whether at least part of a frequency hopping pattern used in the first cell matches with a frequency hopping pattern used in another cell;

instructing from said radio base station to a radio terminal capable of communicating with said radio base station to change the frequency hopping pattern used in the first cell if the detection result indicates that a matching degree is beyond a tolerable range; and

performing communications using another frequency hopping pattern specified by an instruction to change from a predetermined hopping timing.

35. A frequency control method according to claim 34, wherein said detecting step includes the step of counting a number of times a hopping signal of the other cell is received, and said instructing step includes the step of instructing a change of the frequency hopping pattern used in the first cell if the counted number exceeds a predetermined value.

36. A frequency hopping control method according to claim 34, wherein said instructing step includes the step of previously transmitting change notice data indicative of changing timing a plurality of times.

37. A frequency hopping control method in a frequency hopping radio LAN system comprising the steps of:

detecting in a radio base station used in a first cell whether at least part of a frequency hopping pattern used in the first cell matches with a frequency hopping pattern used in another cell;

instructing from said radio base station to a radio terminal capable of communicating with said radio base station to change the order of the frequency hopping pattern used in the first cell if the detection result indicates that a matching degree is beyond a tolerable range; and

performing communications at a hopping frequency on the changed frequency hopping pattern at the next hopping timing.

38. A frequency hopping control method according to claim 37, wherein said detecting step includes the step of counting a number of times a hopping signal of the other cell is received, and said instructing step includes the step of instructing a change in the order of the frequency hopping pattern used in the first cell if the counted number exceeds a predetermined value.

39. A frequency hopping control method according to claim 37, wherein said instructing step includes the step of instructing to once skip a next hopping frequency to hop to the next but one hopping frequency.

40. A frequency hopping control method according to claim 37, wherein said instructing step includes the step of issuing an instruction to repeat the same frequency at the next hopping timing.

41. A frequency hopping control method according to claim 37, wherein said instructing step includes the step of previously transmitting change notice data indicative of changing timing a plurality of times.