Handover control method and apparatus using fuzzy logic

• US 6,141,553 A
• Filed: 01/20/1998
• Issued: 10/31/2000
• Est. Priority Date: 01/20/1998
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Fernandez, Christopher L., Ramesh, Masoor, Hoch, James E., Kurdukar, Prashant J., Herpers, Martine M.
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/009,147
• Time in Patent Office: 1,015 Days
• Field of Search: 455/436, 455/437, 455/438, 455/440, 455/441, 455/443, 455/444, 455/69, 455/70, 455/226.2, 370/331, 370/332, 370/333, 706/1, 706/4, 706/14
• US Class Current: 455/436
• CPC Class Codes: H04W 36/24 Reselection being triggered by specific parameters

Abstract

A method and an apparatus for using fuzzy logic to determine when handovers are desirable and the extent to which the radio transmission power in a cellular telephone network should be adjusted. The mobile phone and the base transceiver station measure certain system parameters, including rate of handover, quality, distance, level, call duration, and power. These measurements are input to a fuzzifier. The fuzzifier applies standard fuzzy-set-theory membership functions to the measurements, and the fuzzifier outputs a set of fuzzy variables corresponding to the measurements. The fuzzifier outputs are input to an inference engine. The inference engine contains a set of rules that, when applied to the inference engine inputs, indicate: when a handover should be performed; when a handover should not be performed; and the amount by which, if any, the transmission power should be adjusted.

Claims

1. A method for using fuzzy logic to determine whether to handover a call in a wireless telephone network, said method comprising the steps of:

generating at least one fuzzy inference engine input based on rate or handover and/or call duration, wherein said rate of handover and/or call duration comprises any rate of at least three possible rates of handover and/or any call duration of at least three possible call durations;

receiving fuzzy inference engine inputs comprising said at least one inference engine input; and

generating a fuzzy inference engine output indicating whether a handover is desirable by applying said fuzzy inference engine inputs to a pre-defined set of rules contained in an inference engine.

2. The method of claim 1 further comprising, in combination, the step of generating a de-fuzzified inference engine output based upon said fuzzy inference engine output, said de-fuzzified inference engine output indicating whether to perform said handover.

3. The method of claim 1 wherein said fuzzy inference engine output indicates whether a handover is desirable and how much of a change should be made to the transmission power used for transmitting said call.

4. A method for using fuzzy logic to determine whether to handover a call in a wireless telephone network, said method comprising the steps of:

(a) generating fuzzy inference engine inputs based upon pre-determined criteria comprising rate of handover and/or call duration, wherein said rate of handover and/or call duration comprises any rate of at least three possible rates of handover and/or any call duration of at least three possible call durations; and

(b) generating a fuzzy inference engine output indicating whether a handover is desirable by applying said fuzzy inference engine inputs to a pre-defined set of rules contained in an inference engine.

5. The method of claim 4 further comprising, in combination, the step of generating a de-fuzzified inference engine output based upon said fuzzy inference engine output, said de-fuzzified inference engine output indicating whether to perform said handover.

6. The method of claim 4 wherein said fuzzy inference engine output indicates whether a handover is desirable and how much of a change should be made to the transmission power used for transmitting said call.

7. The method of claim 4 wherein said generating said fizzy inference engine inputs comprises generating at least one of said fuzzy inference engine inputs based upon rate of handover.

8. The method of claim 4 further comprising, in combination, the step of generating at least one of said fuzzy inference engine inputs based upon quality.

9. The method of claim 4 further comprising, in combination, the step of generating at least one of said fuzzy inference engine inputs based upon distance.

10. The method of claim 4 further comprising, in combination, the step of generating at least one of said fuzzy inference engine inputs based upon level.

11. The method of claim 4 wherein said generating fuzzy inference engine inputs comprises generating at least one of said fuzzy inference engine inputs based upon call duration.

12. A computer controlled telecommunications system, at least partly controlled by using fuzzy logic, said system comprising:

(a) means for generating fuzzy inference engine inputs based upon information, obtained from said telecommunications system, comprising rate of handover and/or call duration, wherein said rate of handover and/or call duration comprises any rate of at least three possible rates of handover and/or any call duration of at least three possible call durations; and

(b) means for generating a fuzzy inference engine output indicating whether a handover is desirable by applying said fuzzy inference engine inputs to a pre-defined set of rules contained in an inference engine.

13. An apparatus for using fuzzy logic to determine whether to handover a call in a wireless telephone network, said apparatus comprising:

(a) means for generating fuzzy inference engine inputs based upon pre-determined criteria comprising rate of handover and/or call duration, wherein said rate of handover and/or call duration comprises any rate of at least three possible rates of handover and/or any call duration of at least three possible call durations; and

(b) means for generating a fuzzy inference engine output indicating whether a handover is desirable by applying said fuzzy inference engine inputs to a pre-defined set of rules contained in an inference engine.

14. The apparatus of claim 13 further comprising, in combination, means for generating a de-fuzzified inference engine output based upon said fuzzy inference engine output, said de-fuzzified inference engine output indicating whether to perform said handover.

15. The apparatus of claim 13 wherein said fuzzy inference engine output indicates whether a handover is desirable and the amount by which the transmission power for said call should be changed.

16. The apparatus of claim 13 wherein said means for generating fuzzy inference engine inputs comprises means for generating at least one of said fuzzy inference engine inputs based upon rate of handover.

17. The apparatus of claim 13 further comprising, in combination, means for generating at least one of said fuzzy inference engine inputs based upon quality.

18. The apparatus of claim 13 further comprising, in combination, means for generating at least one of said fuzzy inference engine inputs based upon distance.

19. The apparatus of claim 13 further comprising, in combination, means for generating at least one of said fuzzy inference engine inputs based upon level.

20. The apparatus of claim 13 wherein said means for generating fizzy inference engine inputs comprises means for generating at least one of said fuzzy inference engine inputs based upon call duration.

21. An apparatus for using fuzzy logic to determine whether to handover a call in a wireless telephone network, said apparatus comprising:

(a) a base transceiver station having one or more outputs;

(b) a call processing calculator having one or more outputs;

(c) a fuzzifier having two sets of inputs and a set of outputs, said first set of fuzzifier inputs being coupled to said base transceiver station outputs and said second set of fuzzifier inputs being coupled to said call processing calculator outputs, at least one of said fuzzy inference engine inputs being based on rate of handover and/or call duration, wherein said rate of handover and/or call duration comprises any rate of at least three possible rates of handover and/or any call duration of at least three possible call durations; and

(d) an inference engine having;

(1) inputs that are coupled to said fuzzifier outputs,

(2) an output, and

(3) a pre-determined set of rules to be applied to said inference engine inputs.

22. The apparatus of claim 21 further comprising a defuzzifier having an output and an input, said defuzzifier input being coupled to said inference engine output.

23. The apparatus of claim 21 wherein at least one of said fuzzy inference engine inputs is based upon rate of handover.

24. The apparatus of claim 21 further comprising at least one of said fuzzy inference engine inputs being based upon quality.

25. The apparatus of claim 21 further comprising at least one of said fuzzy inference engine inputs being based upon distance.

26. The apparatus of claim 21 further comprising at least one of said fuzzy inference engine inputs being based upon level.

27. The apparatus of claim 21 wherein at least one of said fuzzy inference engine inputs is based upon call duration.

28. A method for using fuzzy logic to determine whether to handover a call in a wireless telephone network, said method comprising the steps of:

(a) generating fuzzy inference engine inputs based upon pre-determined criteria wherein at least one of said fuzzy inference engine inputs is based upon any rate of handover of at least three possible rates of handover, at least one of said fuzzy inference engine inputs is based upon quality, at least one of said fuzzy inference engine inputs is based upon distance, at least one of said fuzzy inference engine inputs is based upon level, at least one of said fuzzy inference engine inputs is based upon any call duration of at least three possible call durations, and at least one of said fuzzy inference engine inputs is based upon power;

(b) generating a fuzzy inference engine output indicating whether a handover is desirable by applying said fuzzy inference engine inputs to a pre-defined set of rules contained in an inference engine; and

(c) generating a de-fuzzified inference engine output based upon said fuzzy inference engine output, said de-fuzzified inference engine output indicating whether to perform said handover and how much of a change should be made to the transmission power used for transmitting said call.