System and method for coverage and interference prediction and tradeoff

• US 6,535,747 B1
• Filed: 12/23/1999
• Issued: 03/18/2003
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Shah, Ali R., Hʼmimy, Hossam
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): TRAN, PABLO N
• Application Number:
  US09/470,912
• Time in Patent Office: 1,181 Days
• Field of Search: 455/446, 455/453, 455/452, 455/522, 455/69, 455/525, 455/53.4, 455/56.1, 455/33.2, 455/33.3, 455/62-65, 455/67.1, 455/67.6, 455/513, 455/63, 455/451, 370/329, 370/332, 370/333, 375/202, 375/231, 375/326, 375/330, 375/296, 375/299
• US Class Current: 455/522
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 52/223 predicting future states of the transmission
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters

Abstract

A method and system of optimizing the signal strength and interference characteristics of a wireless telecommunications network which includes a plurality of cells with at least one of the cells being disturbed (the “disturbed cell”) by events occurring in one or more offending cells. The method comprises the step of computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells. The distribution of disturbance events is then utilized to predict changes in coverage of the offending cells as changes in the carrier-to-interference (C/I) ratio of the disturbed cell are made. Such predictions then lead to modifying the power levels of wireless components in the network to reach acceptable tradeoffs between interference and coverage. Thus, the tradeoff is a function of the predicted changes in C/I and acceptable coverage and interference thresholds for the network.

Claims

1. In a wireless telecommunications network including a plurality of cells with at least one of said cells being disturbed (the “

disturbed cell”

) by events occurring in one or more offending cells, a method of optimizing the signal strength and interference characteristics of the network comprising the steps of;

computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells;

utilizing the distribution of disturbance events to predict changes in coverage of the offending cells as changes in the carrier-to-interference (C/I) ratio of the disturbed call are made; and

modifying the power levels of wireless components in the network to reach acceptable tradeoffs between interference and coverage, said tradeoff being a function of the predicted changes in C/I and accept able coverage and interference thresholds for the network.

2. The method according to claim 1 wherein said step of computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells further comprises the step of computing the signal strength for calls in progress and calls not in progress (on an idle channel), wherein said signal strength is utilized in calculating carrier-to-interference (C/I) probabilities.

3. The method according to claim 1 wherein said step of computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells further comprises the step of defining regions based on carrier-to-interference (C/I) ratio levels.

4. The method according to claim 3 wherein said defining step further comprises the step of identifying an acceptable threshold for said network for defining said regions.

5. The method according to claim 1 wherein said utilizing step further comprises the step of calculating the improvement in carrier-to-interference (C/I) ratio level in said disturbed cell and the effect in C/I ratio level in said offending cells.

6. The method according to claim 5 wherein said calculating step further comprises the step of increasing the signal strength in said offending cells while decreasing the coverage provided by said disturbed cell.

7. The method according to claim 6 wherein said steps of increasing and decreasing, respectively, further comprise the step of adjusting said signal strength and interference so as to avoid a significant decrease in coverage in said offending cells.

8. The method according to claim 5 wherein said calculating step further comprises the step of decreasing the signal strength in said offending cells while increasing the coverage provided by said disturbed cell.

9. The method according to claim 1 wherein said step of modifying the power levels further comprises the steps of:

checking whether the improved carrier-to-interference ratio level (GCI) for a higher power setting (Power+Delta) is acceptable;

setting the recommended mobile station power to Power+Delta if said GCI is positive and the higher power setting is acceptable;

determining if the power for a weaker setting is acceptable if said GCI for Power+Delta is not acceptable; and

retaining the current setting if neither weaker nor higher power settings are acceptable.

10. In a wireless telecommunications network including a plurality of cells with at least one of said cells being disturbed (the “

disturbed cell”

) by events occurring in one or more offending cells, a system of optimizing the signal strength and interference characteristics of the network comprising;

means for computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells;

means for utilizing the distribution of disturbance events to predict changes in coverage of the offending cells as changes in the carrier-to-interference (C/I) ratio of the disturbed cell are made; and

means for modifying the power levels of wireless components in the network to reach acceptable tradeoffs between interference and coverage, said tradeoff being a function of the predicted changes in C/I and acceptable coverage and interference thresholds for the network.

11. The system according to claim 10 wherein said means for computing a distribution of disturbance events in the disturbed call as a function of disturbances created by the offending cells further comprises means for computing the signal strength for calls in progress and call not in progress (on an idle channel), wherein said signal strength is utilized in calculating carrier-to-interference (C/I) probabilities.

12. The system according to claim 10 wherein said means for computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells further comprises means for defining regions based on carrier-to-interference (C/I) ratio levels.

13. The system according to claim 12 wherein said means for defining further comprises means for identifying an acceptable threshold for said network for defining said regions.

14. The system according to claim 10 wherein said means for utilizing further comprises means for calculating the improvement in carrier-to-interference (C/I) ratio level in said disturbed cell and the effect in C/I ratio level in said offending cells.

15. The system according to claim 14 wherein said means for calculating further comprises means for increasing the signal strength in said offending cells while decreasing the coverage provided by said disturbed cell.

16. The system according to claim 15 wherein said means for increasing and decreasing, respectively, further comprises means for adjusting said signal strength and interference so as to avoid a significant decrease in coverage in said offending cells.

17. The system according to claim 14 wherein said means for calculating further comprises means for decreasing the signal strength in said offending cells while increasing the coverage provided by said disturbed cell.

18. The system according to claim 10 wherein said means for modifying the power levels further comprises:

means for checking whether said improvement in carrier-to-interference ratio level (GCI) for a higher power setting (Power+Delta) is acceptable;

means for setting the recommended mobile station power to Power+Delta if said GCI is positive and the higher power setting is acceptable;

means for determining if the power for a weaker setting is acceptable said GCI for Power+Delta is not acceptable; and

means for retaining the current setting if neither weaker nor higher power settings are acceptable.

19. In a wireless telecommunications network including a plurality of cells with at least one of said cells being disturbed (the “

disturbed cell”

) by events occurring in one or more offending cells, a program product for optimizing the signal strength and interference characteristics of the network comprising;

instruction means for computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells;

instruction means for utilizing the distribution of disturbance events to predict changes in coverage of the offending cells as changes in the carrier-to-interference (C/I) ratio of the disturbed cell are made; and

instruction means for modifying the power levels of wireless components in the network to reach acceptable tradeoffs between interference and coverage, said tradeoff being a function of the predicted changes in C/I and acceptable coverage and interference thresholds for the network.

20. The program product according to claim 19 wherein said instruction means for computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells further comprises instruction means for computing the signal strength for calls in progress and calls not in progress (on an idle channel), said signal strength for utilizing in calculating carrier-to-interference (C/I) probabilities.

21. The program product according to claim 19 wherein said instruction means for computing a distribution of disturbance events in the disturbed cell as a function of disturbances created by the offending cells further comprises instruction means for defining regions based on carrier-to-interference (C/I) ratio levels.

22. The program product according to claim 21 wherein said instruction means for defining further comprises instruction means for identifying an acceptable threshold for said network for defining said regions.

23. The program product according to claim 19 wherein said instruction means for utilizing further comprises instruction means for calculating the improvement in carrier-to-interference (C/I) ratio level in said disturbed cell and the effect in C/I ratio level in said offending cells.

24. The program product according to claim 23 wherein said instruction means for calculating further comprises instruction means for increasing the signal strength in said offending cells while decreasing the coverage provided by said disturbed cell.

25. The program product according to claim 24 wherein said instruction means for increasing and decreasing, respectively, further comprises instruction means for adjusting said signal strength and interference so as to avoid a significant decrease in coverage in said offending cells.

26. The program product according to claim 23 wherein said instruction means for calculating further comprises instruction means for decreasing the signal strength in said offending cells while increasing the coverage provided by said disturbed cell.

27. The program product according to claim 19 wherein said instruction means for modifying the power levels further comprises:

instruction means for checking whether the improved carrier-to-interference ratio level (GCI) for a higher power setting (Power+Delta) is acceptable;

instruction means for setting the recommended mobile station power to Power+Delta if said GCI is positive and the higher power setting is acceptable;

instruction means for determining if the power for a weaker setting is acceptable if said GCI for Power+Delta is not acceptable; and

instruction means for retaining the current setting if neither weaker nor higher power settings are acceptable.