Method of tuning handoff neighbor lists

• US 7,065,361 B1
• Filed: 12/06/2001
• Issued: 06/20/2006
• Est. Priority Date: 12/08/2000
• Status: Expired due to Term

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Fortuna, Frederick L.
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): RAMOS FELICIANO, ELISEO
• Application Number:
  US10/006,080
• Time in Patent Office: 1,657 Days
• Field of Search: 455/436, 455438-440, 455442-444, 455/446, 455/449, 455/450, 455/452.1, 455/452.2, 455/513, 455/509, 455/525, 455/524, 455/433, 455/422.1, 455/517, 455/403, 455/437, 455/441, 370331-334
• US Class Current: 455/438
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 36/0061 of neighbour cell information

Abstract

A wireless telecommunications network includes a mobile switching center (MSC) that controls a plurality of base stations. Each base station defines one or more wireless coverage areas, which may be termed “cells” or “sectors.” Associated with each of these wireless coverage areas is a “neighbor list” that lists a number of other wireless coverage areas to which handoffs are preferably made. The MSC has access to a database of handoff statistics and to a database of neighbor lists for the wireless coverage areas that it controls. The handoff statistics provide an indication of the frequencies at which handoffs have occurred between the various wireless coverage areas. To tune a neighbor list for a given wireless coverage area, the other wireless coverage areas are ranked based on the frequency of handoffs involving that wireless coverage area and the given wireless coverage area, as reflected in the handoff statistics. The wireless coverage areas with the highest handoff frequencies are added to the neighbor list for the given wireless coverage area. In preferred embodiments, the wireless coverage areas in a neighbor list may be further categorized into a first priority set, a second priority set, and a third priority set, based on their handoff frequencies.

Claims

1. In a wireless telecommunications network having a plurality of wireless coverage areas, a record of handoff statistics, and a neighbor list associated with at least a given one of said plurality of wireless coverage areas, wherein said wireless telecommunications system makes handoffs from said given wireless coverage area based on signal strength measurements involving wireless coverage areas identified in said neighbor list, a method for tuning said neighbor list for said given wireless coverage area, said method comprising the steps of:

selecting m relevant coverage areas from said plurality of wireless coverage areas, exclusive of said given coverage area;

for each one of said m relevant coverage areas, calculating, based at least in part on said handoff statistics, a corresponding ranking number related to a frequency of handoffs involving said given coverage area and said one of said m relevant coverage areas, thereby providing m ranking numbers;

ranking said m relevant coverage areas based on their corresponding ranking numbers;

identifying a first set consisting of a first number of highest-ranked coverage areas from among said m relevant coverage areas; and

revising said neighbor list to identify each of said first number of coverage areas in said first set.

2. The method of claim 1, wherein said first set defines a first priority set in said neighbor list.

3. The method of claim 2, further comprising the steps of:

identifying a second set consisting of a second number of highest-ranking coverage areas from among said m relevant coverage areas not in said first set; and

revising said neighbor list to identify each of said second number of coverage areas in said second set.

4. The method of claim 3, said second set defines a second priority set in said neighbor list.

5. The method of claim 4, further comprising the steps of:

identifying a third set consisting of a third number of highest-ranked relevant coverage areas from among said m relevant coverage areas not in said first or second sets; and

revising said neighbor list to identify each of said third number of coverage areas in said third set.

7. The method of claim 1, further comprising the steps of:

summing said m ranking numbers to provide a total sum; and

summing the ranking numbers of relevant coverage areas in said first set to provide a first sum.

8. The method of claim 7, wherein said first sum is no greater than a first predetermined percentage of said total sum.

9. The method of claim 7, further comprising the steps of:

summing said m ranking numbers to provide a total sum; and

summing the ranking numbers of relevant coverage areas in said first and second sets to provide a second sum.

10. The method of claim 9, wherein said second sum is no greater than a second predetermined percentage of said total sum.

11. The method of claim 9, further comprising the steps of:

summing said m ranking numbers to provide a total sum; and

summing the ranking numbers of relevant coverage areas in said first, second, and third sets to provide a third sum.

12. The method of claim 11, wherein said third sum is no greater than a third predetermined percentage of said total.

6. The method of 5, wherein said third set defines a third priority set in said neighbor list.

13. In a wireless telecommunications network having a plurality of wireless coverage areas, a database of handoff statistics, and a neighbor list associated with at least a given one of said plurality of wireless coverage areas, wherein said wireless telecommunications system makes handoffs from said given wireless coverage area based on signal strength measurements involving wireless coverage areas identified in said neighbor list, said neighbor list including a first priority set, a second priority set, and a third priority set, a method for tuning said neighbor list, said method comprising the steps of:

selecting m relevant coverage areas from said plurality of wireless coverage areas, exclusive of said given coverage area;

for each of one of said m relevant coverage areas calculating, based at least in part on said handoff statistics, a corresponding ranking number related to a frequency of handoffs involving said given coverage area and said one of said m relevant coverage areas, thereby providing m ranking numbers;

ranking said m relevant coverage areas based on their corresponding ranking numbers;

finding a largest integer, p, that satisfies at least a first predetermined criterion;

finding a largest integer, q, that satisfies at least a second predetermined criterion;

finding a largest integer, r, that satisfies at least a third predetermined criterion;

identifying a first priority set consisting of p highest-ranked coverage areas from among said m relevant coverage areas;

identifying a second priority set consisting of q highest-ranked coverage areas from among said m relevant coverage areas not in said first priority set;

identifying a third priority set consisting of r highest-ranked coverage areas from among said m relevant coverage areas not in said first or second priority sets; and

revising said neighbor list to identify each of said p coverage areas in said first priority set, each of said q coverage areas in said second priority set, and each of r coverage areas in said third priority set.

14. The method of claim 13, further comprising the steps of:

summing said m ranking numbers to provide a total sum;

summing the ranking numbers of relevant coverage areas in said first priority set to provide a first sum,

wherein said at least a first predetermined criterion requires said first sum to be no greater than a first predetermined percentage of said total sum and requires p to be no greater than a first predetermined number.

15. The method of claim 14, further comprising the steps of:

summing said m ranking numbers to provide a total sum;

summing the ranking numbers of relevant coverage areas in said first and second priority sets to provide a second sum,

wherein said at least a second predetermined criterion requires said second sum to be no greater than a second predetermined percentage of said total sum and requires p+q to be no greater than a second predetermined number.

16. The method of claim 15, further comprising the steps of:

summing said m ranking numbers to provide a total sum;

summing the ranking numbers of relevant coverage areas in said first, second, and third priority sets to provide a third sum,

wherein said at least a third predetermined criterion requires said third sum to be no greater than a third predetermined percentage of said total and requires p+q+r to be no greater than a third predetermined number.

17. The method of claim 13, further comprising the step of:

if r is less than a fourth predetermined number, identifying in said third priority set at least one of said m relevant coverage areas not previously identified in said neighbor list.