Method for generating a handoff candidate list

• US 5,640,676 A
• Filed: 05/11/1995
• Issued: 06/17/1997
• Est. Priority Date: 05/11/1995
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gallagher, Timothy J., Garncarz, Jeffrey Robert, Goldstein, Brent Lane
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): VO, NGUYEN THANH
• Application Number:
  US08/439,149
• Time in Patent Office: 768 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/33.3, 455/56.1, 455/54.1, 455/63, 455/67.1, 455/67.3, 379/60, 379/59
• US Class Current: 455/436
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/322 by location data

Abstract

In a cellular communication system (40) a handoff candidate list is generated for a source sector (51) by eliminating (12) from a list of potential handoff candidates (52-56) any sectors having an interference parameter exceeding a threshold value. The list is further reduced by determining (21) a handoff radius (60) and eliminating any candidate sectors (52-56) that fall outside the handoff radius (60). Candidate sectors (52-56) that do not have overlapping coverage areas are also eliminated (23). In addition, candidate sectors (52-56) having a relative angle of sight to the source sector (51) that exceeds a maximum angle are also eliminated (24). Finally, the list is reduced (15) to a preset number of candidates dependent upon the interference parameter.

Claims

1. A method for generating a handoff candidate list for a source sector comprising the steps of:

generating a ranked list of a plurality of handoff candidates by ranking a plurality of potential handoff sectors in order of an interference parameter;

eliminating a candidate of said plurality of handoff candidates from said ranked list based on physical location in relation to said source sector; and

eliminating a target sector of said plurality of handoff candidates from said ranked list of said source sector unless said source sector is present on a handoff candidate list for said target sector, thereby forming said handoff candidate list.

2. The method of claim 1 further comprising the step of eliminating a candidate of said plurality of handoff candidates from said ranked list for which said interference parameter exceeds a threshold interference parameter.

3. The method of claim 1 wherein said step of forming said handoff candidate list comprises the steps of:

determining a handoff radius; and

eliminating a candidate of said plurality of handoff candidates from said ranked list which falls outside said handoff radius.

4. The method of claim 1 wherein said step of eliminating said candidate of said plurality of handoff candidates comprises the step of eliminating a target sector from said ranked list unless said target sector has a coverage area which overlaps a coverage area of said source sector.

5. The method of claim 1 further comprising the step of selecting a preset number of said plurality of handoff candidates which remain on said ranked list.

6. The method of claim 1 wherein said interference parameter comprises a carrier-to-interference ratio.

7. The method of claim 1 wherein said interference parameter comprises a relative signal strength.

8. The method of claim 1 further comprising the step of eliminating a target sector of said plurality of handoff candidates from said ranked list of said source sector if a relative angle between said source sector and said target sector exceeds a maximum value.

9. A method for generating a handoff candidate list for a source sector comprising the steps of:

generating a ranked list of a plurality of handoff candidates by ranking a plurality of potential handoff sectors in order of an interference parameter;

computing a handoff radius;

eliminating a candidate of said plurality of handoff candidates from said ranked list which falls outside said handoff radius;

eliminating a target sector from said ranked list unless said target sector has a coverage area which overlaps a coverage area of said source sector;

eliminating a target sector of said plurality of handoff candidates from said ranked list of said source sector unless said source sector is present on a handoff candidate list for said target sector, thereby forming said handoff candidate list.

10. The method of claim 9 further comprising the step of eliminating a candidate of said plurality of handoff candidates from said ranked list for which said interference parameter exceeds a threshold interference parameter.

11. The method of claim 9 further comprising the step of selecting a preset number of said plurality of handoff candidates which remain on said ranked list.

12. The method of claim 9 wherein said interference parameter comprises a carrier-to-interference ratio.

13. The method of claim 9 wherein said interference parameter comprises a relative signal strength.

14. The method of claim 9 further comprising the step of eliminating a target sector of said plurality of handoff candidates from said ranked list of said source sector if a relative angle between said source sector and said target sector exceeds a maximum value.