System and method for frequency reuse in a four cell plan

• US 6,154,654 A
• Filed: 05/07/1998
• Issued: 11/28/2000
• Est. Priority Date: 05/07/1998
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Mao, Tom
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US09/074,253
• Time in Patent Office: 936 Days
• Field of Search: 455/446, 455/447, 455/450, 455/449
• US Class Current: 455/446
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

A telecommunications system and method for a frequency re-use plan is disclosed which reduces the adjacent channel interference between cells, while maintaining good co-channel interference in a four cell frequency reuse plan with a center-excited three sector directional pattern. This can be accomplished by structuring the four cell frequency reuse plan such that no adjacent cells use adjacent channels. As a result, the adjacent channel interference can be minimized, the radio coverage can be extended and in-building penetration can be improved.

Claims

1. A telecommunications system for reducing the adjacent channel interference between adjacent ones of a plurality of cells within a frequency reuse plan, said telecommunications system comprising:

a plurality of cell clusters, each said cell cluster comprising four cells, each of said cells having a substantially hexagon shape and three sectors, each of said sectors having a substantially rhombus shape; and

a plurality of base stations, each said cell having a respective one of said base stations substantially centrally located therein, each of said base stations having three antenna-pointing azimuths associated therewith, each of said sectors within each of said cells having a respective one of said antenna-pointing azimuths associated therewith, a first one of said antenna-pointing azimuths being points about sixty degrees from north along a north-south axis, a second one of said antenna-pointing azimuths being pointed about one hundred eighty degrees from north along said north-south axis, and a third one of said antenna-pointing azimuths being pointed about three hundred degrees from north along said north-south axis.

2. The telecommunications system of claim 1, wherein said substantially hexagon shape has six sides, each of said antenna-pointing azimuths of each of said base stations being pointed toward respective ones of said sides.

3. The telecommunications system of claim 1, wherein each said base station within each said cell has a transmitting antenna and a receiving antenna for each said sector, the respective said transmitting antenna and receiving antenna in a given one of said sectors being pointed in the direction of said antenna-pointing azimuth of said given sector.

4. The telecommunications system of claim 1, wherein each said cell cluster has a cluster frequency group associated therewith, and each said cell within a given one of said cell clusters has a cell frequency group associated therewith, each said cell frequency group within said given cell cluster being different.

5. The telecommunications system of claim 4, wherein each said cell cluster has the same cluster frequency group.

6. The telecommunications system of claim 5, wherein each said cell frequency group associated with a given one of said cells being divided into at least three sub-frequency groups, each said sector within said given cell having one of said sub-frequency groups associated therewith.

7. The telecommunications system of claim 6, wherein said sub-frequency group associated with a first one of said sectors of said given cell is adjacent to said sub-frequency group associated with a first one of said sectors of a second one of said cells within said given cell cluster.

15. The telecommunications system of claim 7, wherein said sub-frequency group of a third one of said sectors of a fourth one of said cells in said given cell cluster is adjacent to said sub-frequency group of said first sector of said given cell, said third sector of said fourth cell being physically adjacent to said first sector of said given cell.

16. The telecommunications system of claim 15, wherein each said sub-frequency group has a plurality of channels associated therewith, at least one of, but not all of, said plurality of channels associated with said sub-frequency group of said first sector of said given cell being swapped with an adjacent one of said plurality of channels associated with said sub-frequency group of said first sector of said second cell.

8. A method for planning a cell cluster layout which reduces the adjacent channel interference between adjacent ones of a plurality of cells within a telecommunications system, each said cell having a respective one of a plurality of base stations substantially centrally located therein, said method comprising the steps of:

establishing three antenna-pointing azimuths associated with said each base station, four of cells comprising a cell cluster, each of said cells having a substantially hexagon shape and three sectors, each of said sectors having a substantially rhombus shape, each of said sectors within each of said cells having a respective one of said antenna pointing azimuths associated therewith;

pointing a first one of said antenna-pointing azimuths for each said base station about sixty degrees from north along a north-south axis;

pointing a second one of said antenna-pointing azimuths for each said base station about one hundred eighty degrees from north along said north-south axis; and

pointing a third one of said antenna-pointing azimuths for each said base station about three hundred degrees from north along said north-south axis.

9. The method of claim 8, wherein said substantially hexagon shape has six sides, and further comprising, after said step of establishing, the step of:

pointing each of said antenna-pointing azimuths of each of said base stations toward respective ones of said sides.

10. The method of claim 8, wherein each said base station within each said cell has a transmitting antenna and a receiving antenna for each said sector, the respective said transmitting antenna and receiving antenna in a given one of sectors being pointed in the direction of said antenna-pointing azimuth of said given sector.

11. The method of claim 8, wherein each said cell cluster has a cluster frequency group associated therewith, and each said cell within a given one of said cell clusters has a cell frequency group associated therewith, each said cell frequency group within said given cell cluster being different.

12. The method of claim 11, wherein each said cell cluster has the same cluster frequency group.

13. The method of claim 12, wherein each said cell frequency group associated with a given one of said cells being divided into at least three sub-frequency groups, each said sector within said given cell having one of said sub-frequency groups associated therewith.

14. The method of claim 13, wherein said sub-frequency group associated with a first one of said sectors of said given cell is adjacent to said sub-frequency group associated with a first one of said sectors of a second one of said cells within said given cell cluster.

17. The method of claim 14, wherein said sub-frequency group of a third one of said sectors of a fourth one of said cells in said given cell cluster is adjacent to said sub-frequency group of said first sector of said given cell, said third sector of said fourth cell being physically adjacent to said first sector of said given cell.

18. The method of claim 14, wherein each said sub-frequency group has a plurality of channels associated therewith, at least one of, but not all of, said plurality of channels associated with said sub-frequency group of said first sector of said given cell being swapped with an adjacent one of said plurality of channels associated with said sub-frequency group of said first sector of said second cell.