N=4 directional frequency assignment in a cellular radio system

• US 5,970,411 A
• Filed: 08/08/1997
• Issued: 10/19/1999
• Est. Priority Date: 08/08/1997
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Corporation
• Inventors: Faruque, Saleh
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Congvan
• Application Number:
  US08/907,520
• Time in Patent Office: 802 Days
• Field of Search: 455/447, 455/450, 455/446, 455/448, 455/452, 455/449, 455/464, 455/524, 455/500, 455/507, 455/62, 455/63, 455/67, 455/67.3
• US Class Current: 455/447
• 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

The process of the present invention is based on a tri-cellular, hexagonal platform where six, or a multiple of six, frequency groups are directionalized and reused in the same direction. Directional antennas are located in the center of each tri-cell group. Each antenna radiates into a 120° sector of the tri-cell group. The reused frequency groups are aligned along the 0°, 120°, and 240° axes of each cell. Each axis has three layers, the two outer layers having an identical frequency reuse series. The frequency groups are reused in the same direction along each axis, reducing the number of dominant interfering cells to one.

Claims

1. A method for frequency allocation in a cellular system, the cellular system having a plurality of available frequencies and comprising a plurality of cells, the method comprising the steps of:

forming a tri-cell group of cells comprising three of the plurality of cells, the tri-cell group having three frequency reuse axes, each frequency reuse axis having three layers;

grouping the plurality of available frequencies into a predetermined number of frequency groups;

grouping the predetermined number of frequency groups into six different series of frequency groups such that each series of frequency groups comprises two different frequency groups, three of the six series of frequency groups comprising odd frequency groups and the remaining three of the six series of frequency groups comprising even frequency groups;

assigning the odd series of the frequency groups to the cells on a first layer of the three layers along each frequency reuse axis of the three frequency reuse axes; and

assigning the even series of the frequency groups to the cells on the remaining layers of the three layers along each frequency reuse axis of the three frequency reuse axes.

2. The method of claim 1 and further including the step of repeating the tri-cell group to cover a geographical region.

3. The method of claim 1 wherein the predetermined number of frequency groups is equal to a multiple of 6.

4. The method of claim 1 wherein the second and third frequency layers are on either side of the first layer.

5. A method for frequency allocation in a cellular system, the cellular system having a plurality of available frequencies and comprising a plurality of cells, the method comprising the steps of:

forming a tri-cell group of cells comprising three of the plurality of cells, the tri-cell group having three frequency reuse axes, each frequency reuse axis having three layers;

grouping the plurality of available frequencies into a predetermined number of frequency groups;

grouping the predetermined number of frequency groups into six different series of frequency groups such that each series of frequency groups comprises two different frequency groups, three of the six series of frequency groups comprising odd frequency groups and the remaining three of the six series of frequency groups comprising even frequency groups;

assigning the even series of the frequency groups to the cells on a first layer of the three layers along each frequency reuse axis of the three frequency reuse axes; and

assigning the odd series of the frequency groups to the cells on the remaining layers of the three layers along each frequency reuse axis of the three frequency reuse axes.

6. The method of claim 5 and further including the step of repeating the cellular cluster to cover a geographical area.

7. The method of claim 5 wherein the predetermined number of frequency groups is equal to a multiple of 6.

8. The method of claim 5 wherein the second and third frequency layers are on either side of the first layer.