Optimizing hand-off neighbor lists for improved system performance

• US 20040121773A1
• Filed: 12/20/2002
• Published: 06/24/2004
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: OʼBrien, Paul S.
• Granted Patent: US 7,155,223 B2
• Time in Patent Office: Days
• US Class Current: 455/438
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists

Abstract

Method for improving hand-off performance in a code-division multiple access (CDMA) cellular telephone system. A preferred embodiment comprises the analysis of saved hand-off information to minimize the size of neighbor lists for each base station in the cellular telephone system. If a requested base station (for example, base station 618) is listed in any neighbor list of any base station (for example, base stations 605, 617, and 620) involved in the hand-off, then the requested base station is not added to any neighbor list. If the requested base station is not the neighbor lists of any of the base stations involved in the hand-off, then it is added to an initial base station'"'"'s neighbor list (base station 605).

Claims

1. A method for creating a neighbor list for use in hand-offs in a cellular communications system comprising:

determining a requested base station, a-reference base station, and a list of other base stations from a saved call;

determining if the requested base station is present in a neighbor list of a base stations listed in the list of other base stations; and

adding the requested base station to a neighbor list for an optimal base station if the requested base station is absent from neighbor lists of the reference base station and all base stations listed in the list of other base stations.

2. The method of claim 1, wherein the saved call is obtained from a list of saved calls generated during normal use of the cellular communications system, and wherein the method is repeated for each saved call in the ordered list.

3. The method of claim 1, wherein the saved call is obtained from an ordered list of saved calls generated during normal use of a cellular communications system, wherein the ordered list of saved calls is sorted by a number of base stations in the list of other base stations of each saved call, and wherein the method begins with a saved call with a fewest number of other base stations and continues with saved calls with increasing number of other base stations.

4. The method of claim 1, wherein the method is executed at a central processor, wherein a neighbor list is created for each base station, and wherein each of the neighbor lists is delivered to a corresponding base station.

5. The method of claim 4, wherein the central processor is a base station manager (BSM).

6. The method of claim 4, wherein the central processor is a remotely connected computer.

7. The method of claim 4, wherein each base station'"'"'s neighbor list can be different.

8. The method of claim 1, wherein the cellular communications system is a code-division multiple access (CDMA) cellular communications system.

9. The method of claim 1, wherein the cellular communications system is an IS95 compliant communications system.

10. The method of claim 1, wherein the cellular communications system is an IS2000 compliant communications system.

11. The method of claim 1, wherein the method is executed periodically to generate up-to-date neighbor lists.

12. The method of claim 1, wherein the addition of the requested base station to the optimal base station'"'"'s neighbor list results in a minimally sized composite neighbor list.

13. A method for optimizing a neighbor list comprising:

selecting a saved call from a list of saved calls;

determining a requested base station, a reference base station, and a list of other base stations from the saved call;

determining if the requested base station is present in a neighbor list of a base stations listed in the list of other base stations;

adding the requested base station to a neighbor list for an optimal base station if the requested base station is absent from neighbor lists of the reference base station and all base stations listed in the list of other base stations; and

repeating for all remaining saved calls in the list of saved calls.

14. The method of claim 13, wherein the list of saved calls contains saved calls listing N other base stations, wherein N is a number from one (1) to six (6).

15. The method of claim 14 further comprising after the repeating:

incrementing N;

obtaining an additional list of saved calls, wherein the additional list of saved calls contains only saved calls listing N base stations;

repeating the selecting, two determining, adding, and first repeating for the additional list of saved calls.

16. The method of claim 15, wherein the method is repeated until N is equal to six (6).

17. The method of claim 13 further comprising after the first determining, skipping the second determining and adding if the requested base station, the reference base station, and the list of other-base-stations have previously appeared in an earlier processed saved call.

18. The method of claim 13, wherein a neighbor list is created for each base station in a cellular communications system, and wherein the method further comprises sending to each base station its neighbor list.

19. A method for populating a neighbor list comprising:

determining a requested base station, a reference base station, and a list of other base stations from call data;

searching each base station'"'"'s neighbor list for an occurrence of the requested base station, wherein each base station is from the list of other base stations;

searching the reference base station'"'"'s neighbor list for an occurrence of the requested base station; and

adding the requested base station to an optimal base station'"'"'s neighbor list if all searches are negative.

20. The method of claim 19, wherein if any of the searches is positive, the method is stopped.

21. The method of claim 19, wherein when added to the reference base station'"'"'s neighbor list, a position of the requested base station in the reference base station'"'"'s neighbor list is based on an identifier of the requested base station.

22. The method of claim 19, wherein the method is repeated for all available call data.