Frequency hopping pattern assignment and control in multiple autonomous collocated radio networks

• US 5,394,433 A
• Filed: 04/22/1993
• Issued: 02/28/1995
• Est. Priority Date: 04/22/1993
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wetterwald, Michelle M., Bauchot, Frederick J., Lanne, Fabien P., Huang, Chia-Chi, Bantz, David F., Natarajan, Kadathur S.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/052,329
• Time in Patent Office: 677 Days
• Field of Search: 375/1
• US Class Current: 375/132
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 2001/7154 with means for preventing interference
• CPC Class Codes: H04B 2001/71563 Acquisition
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A control system for automated management of frequency-hopping in a radio network. The system includes a Wireless Network Manager (WNM) or Controller and a Wireless Control Agent (WCA), which control the distribution and maintenance of hopping patterns in the radio network. In a single cell network, the WNM and the WCA are included in a single base station. In a multiple cell network, the WNM is in a specific station on a LAN, and a WCA is located in each base station on the LAN. In each instance, the WNM is a centralized managing station and the WCA acts as a cell controller.

Claims

1. A method of dynamically managing frequency hopping in a wireless communication network comprising a controller, a plurality of base stations, a local area network interconnecting said base stations with said controller, and a plurality of mobile stations, each said mobile station and base station including a transceiver for wireless bidirectional communication therebetween when in sufficient proximity to each other, said method comprising the steps of:

(a) requesting by a given base station a frequency hopping pattern assignment from said controller;

(b) monitoring by said given base station the frequency hopping pattern of the other ones of said plurality of base stations;

(c) requesting by said given base station a new frequency hopping pattern if another one of said plurality of base stations is using the same frequency hopping pattern as said given base station;

(d) beginning frequency hopping by said given base station;

(e) monitoring by said given base station interference relative to the assigned frequency hopping pattern;

(f) determining by said given base station if frequency hopping pattern revision is necessary as the result of the monitoring of interferences; and

(g) returning to step (b) if revision is necessary, and if revision is not necessary, continuing to hop with the same frequency hopping pattern.

2. The method of claim 1, wherein step (a) includes said controller performing the steps of:

(a) selecting a frequency hopping pattern from a predetermined set of frequency hopping patterns;

(b) determining if the selected frequency hopping pattern has been previously assigned to another one of said plurality of base stations;

(c) returning to step (a) if the selected frequency hopping pattern has previously been assigned; and

(d) communicating the selected frequency hopping pattern to said given base station.

3. The method of claim 1, wherein step (b) includes the steps of:

(a) locking into the frequency hopping pattern of another base station to learn its frequency hopping pattern;

(b) comparing the frequency hopping patterns; and

(c) requesting a new frequency hopping pattern by said given base station if the frequency hopping patterns compare with predetermined limits.

4. The method of claim 1, wherein step (e) includes the steps of:

(a) classifying interference into predetermined groups; and

(b) controlling the interference based on which group it falls into.

5. The method of claim 4, wherein the predetermined groups of interference include periodic interference, continuous interference and bursty interference.

6. The method of claim 5, including the steps of:

(a) controlling periodic interference by a hop insert and delete technique;

(b) controlling continuous interference by a pattern replacement technique; and

(c) controlling bursty interference by a hop advance technique.

7. A method of dynamically managing interference in a wireless communication network comprising a controller, a plurality of base stations, a local area network interconnecting said base stations with said controller, and a plurality of mobile stations, each said mobile station and base station including a transceiver for wireless bidirectional communication therebetween when in sufficient proximity to each other, said method comprising the steps of:

(a) requesting by a given base station a frequency hopping pattern assignment from said controller;

(b) selecting by said controller a frequency hopping pattern from a predetermined set of frequency hopping patterns;

(c) determining by said controller if the selected frequency hopping pattern has been previously assigned to another one of said plurality of base stations;

(d) returning to step (b) by said controller if the selected frequency hopping pattern has previously been assigned;

(e) communicating the selected frequency hopping pattern to said given base station;

(f) locking, by said given base station, into the frequency hopping pattern of another base station to learn its frequency hopping pattern;

(g) comparing the frequency hopping patterns;

(h) requesting a new frequency hopping pattern by said given base station if the frequency hopping patterns compare within predetermined limits;

(i) beginning frequency hopping by said given base station;

(j) monitoring by said given base station interference relative to the assigned frequency hopping pattern;

(k) determining by said given base station if frequency hopping pattern revision is necessary as the result of the monitoring of interferences; and

(l) returning to step (h) if revision is necessary, and if revision is not necessary, continuing to hop with the same frequency hopping pattern.

8. The method of claim 7, wherein step (j) includes the steps of:

(a) classifying interference into predetermined groups; and

(b) controlling the interference based on which group it falls into.

9. The method of claim 8, wherein the predetermined groups of interference include periodic interference, continuous interference and bursty interference.

10. The method of claim 9, including the steps of:

(a) controlling periodic interference by a hop insert and delete technique;

(b) controlling continuous interference by a pattern replacement technique; and

(c) controlling bursty interference by a hop advance technique.

11. A method of dynamically managing interference in a wireless communication network comprising a controller, a plurality of base stations, a local area network interconnecting said base stations with said controller, and a plurality of mobile stations, each said mobile station and base station including a transceiver for wireless bidirectional communication therebetween when in sufficient proximity to each other, said method comprising the steps of:

maintaining an Inactive Channel Table (ICT) in said controller for keeping track of the inactive hopping frequencies in said network, including the time of last use of a hopping frequency, the last time a hopping frequency was replaced and the base stations involved;

maintaining an Active Channel Table (ACT) in each of said base station for keeping track of whether a given hopping frequency has been relatively free of interference and therefore is considered to be good or whether the given hopping frequency has not been relatively free of interference and therefore is considered to be bad and if it has been deleted within a predetermined time;

determining if a given hopping frequency has not been relatively free of interference at a given base station, and if so updating ACT to reflect that the given hopping frequency is considered to be bad;

requesting a new hopping frequency from said controller in response to determining that the given hopping frequency is considered to be bad;

selecting said new hopping frequency from the ICT by said controller, and updating ICT to reflect the selection;

sending the new hopping frequency to each base station that was using the hopping frequency considered to be bad, and

at each base station that was using the hopping frequency considered to be bad, using the new hopping frequency instead.

12. The method of claim 11, wherein the step of selecting said new hopping frequency includes the step of:

finding another frequency in said ICT that is a predetermined number of frequencies away from said given hopping frequency.

13. The method of claim 12, wherein the step of finding another frequency includes the steps of:

determining if there is an unused frequency in said ICT that is more than said predetermined number of frequencies away from said given hopping frequency, and if there is, selecting it as said new hopping frequency, and if there is not;

determining if there is an unused frequency in said ICT that is less than said predetermined number of frequencies away from said given hopping frequency, and if there is, selecting it as said new hopping frequency.

14. Apparatus for dynamically managing frequency hopping in a wireless communication network comprising a controller, a plurality of base stations, a local area network interconnecting said base stations with said controller, and a plurality of mobile stations, each said mobile station and base station including a transceiver for wireless bidirectional communication therebetween when in sufficient proximity to each other, comprising:

(a) means for requesting by a given base station a frequency hopping pattern assignment from said controller;

(b) means for monitoring by said given base station the frequency hopping pattern of the other ones of said plurality of base stations;

(c) means for requesting by said given base station a new frequency hopping pattern if another one of said plurality of base stations is using the same frequency hopping pattern as said given base station;

(d) means for beginning frequency hopping by said given base station;

(e) means for monitoring by said given base station interference relative to the assigned frequency hopping pattern;

(f) means for determining by said given base station if frequency hopping pattern revision is necessary as the result of the monitoring of interferences; and

(g) means for returning to (b) if revision is necessary, and if revision is not necessary, including means for continuing to hop with the same frequency hopping pattern.

15. The apparatus of claim 14, wherein said controller includes:

(a) means for selecting a frequency hopping pattern from a predetermined set of frequency hopping patterns;

(b) means for determining if the selected frequency hopping pattern has been previously assigned to another one of said plurality of base stations;

(c) means for returning to (a) if the selected frequency hopping pattern has previously been assigned; and

(d) communicating the selected frequency hopping pattern to said given base station.

16. The apparatus of claim 14, wherein said means for monitoring the frequency hopping pattern includes:

(a) means for locking into the frequency hopping pattern of another base station to learn its frequency hopping pattern;

(b) means for comparing the frequency hopping patterns; and

(c) means for requesting a new frequency hopping pattern by said given base station if the frequency hopping patterns compare with predetermined limits.

17. The apparatus of claim 14, wherein said means for monitoring interference includes:

(a) means for classifying interference into predetermined groups; and

(b) means for controlling the interference based on which group it falls into.

18. The apparatus of claim 17, wherein the predetermined groups of interference include periodic interference, continuous interference and bursty interference.

19. The apparatus of claim 18, wherein the means for monitoring interference includes:

(a) means for controlling periodic interference by a hop insert and delete technique;

(b) means for controlling continuous interference by a pattern replacement technique; and

(c) means for controlling bursty interference by a hop advance technique.

20. Apparatus for dynamically managing a wireless communication network comprising a controller, a plurality of base stations, a local area network interconnecting said base stations with said controller, and a plurality of mobile stations, each said mobile station and base station including a transceiver for wireless bidirectional communication therebetween when in sufficient proximity to each other comprising:

an Inactive Channel Table (ICT) in said controller for keeping track of the inactive hopping frequencies in said network, including the time of last use of a hopping frequency, the last time a hopping frequency was replaced and the base stations involved;

an Active Channel Table (ACT) in each of said base station for keeping track of whether a given hopping frequency has been relatively free of interference and therefore is considered to be good or whether the given hopping frequency has not been relatively free of interference and therefore is considered to be bad and if it has been deleted within a predetermined time;

means for determining if a given hopping frequency has not been relatively free of interference at a given base station, including means for updating ACT to reflect that the given hopping frequency is considered to be bad;

means for requesting a new hopping frequency from said controller in response to determining that the given hopping frequency is considered to be bad;

means for selecting said new hopping frequency from the ICT by said controller, including means for updating ICT to reflect the selection;

means for sending the new hopping frequency from said controller to each base station that was using the hopping frequency considered to be bad, and

means at each base station that was using the hopping frequency considered to be bad for using the new hopping frequency instead.

21. The apparatus of claim 20, wherein said means for selecting said new hopping frequency includes:

means for finding another frequency in said ICT that is a predetermined number of frequencies away from said given hopping frequency.

22. The apparatus of claim 21, wherein said means for finding another frequency includes:

means for determining if there is an unused frequency in said ICT that is more than said predetermined number of frequencies away from said given hopping frequency, and if there is, means for selecting it as said new hopping frequency, and if there is not;

means for determining if there is an unused frequency in said ICT that is less than said predetermined number of frequencies away from said given hopping frequency, and if there is, means for selecting it as said new hopping frequency.