Directional frequency assignment in a cellular radio system

• US 5,850,608 A
• Filed: 11/08/1996
• Issued: 12/15/1998
• Est. Priority Date: 11/08/1996
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nothern Telecom Limited
• Inventors: Faruque, Saleh
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): Orgad, Edan
• Application Number:
  US08/745,390
• Time in Patent Office: 767 Days
• Field of Search: 455/447, 455/446, 455/448, 455/450, 455/464, 455/509, 455/62
• 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 hexagonal cellular 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 cell. Each antenna radiates into a 60° sector of the cell. 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, each cell comprising six sectors, the method comprising the steps of:

forming a cluster of cells comprising a subset of the plurality of cells, the cluster of cells having a plurality of frequency reuse axes, each frequency reuse axis having a plurality of layers, each layer on a first frequency reuse axis of the plurality of frequency reuse axes being parallel to the other layers on the first frequency reuse axis;

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

assigning a first series of the frequency groups to the sectors on a first layer of the plurality of layers along the first frequency reuse axis of the plurality of frequency reuse axes, the first series being composed only of odd numbered frequency groups; and

assigning a second series of the frequency groups, the second series being composed only of even numbered frequency groups, to the sectors on a second and third layer of the plurality of layers along the first frequency reuse axis of the plurality of frequency reuse axes, the second and third layers each being adjacent the first layer.

2. The method of claim 1 and further including the step of repeating the cellular cluster to cover a geographical region, comprises a predetermined number of even numbered frequency groups.

3. The method of claim 2 wherein the cellular system has a first frequency reuse distance in a first direction and a second frequency reuse distance in a second direction.

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

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

6. A method for frequency allocation in a cellular system, the cellular system having a plurality of available frequencies and comprising a plurality of cells, each cell comprising six sectors and a plurality of directional antennas, each antenna radiating into a sector of the cell, the method comprising the steps of:

forming a cellular cluster from seven of the cells, the cellular cluster having a plurality of frequency reuse axes, each frequency reuse axis comprising a plurality of layers parallel to each other, the cellular cluster comprising a center cell and six surrounding cells;

grouping the plurality of available frequencies into a predetermined number of frequency groups, the frequency groups being numbered in a sequential manner;

allocating a first series of odd numbered frequency groups along a first layer of a first frequency reuse axis;

allocating a second series of even numbered frequency groups along a second and a third layer of the first frequency reuse axis;

allocating a third series of odd numbered frequency groups along a first layer of a second frequency reuse axis;

allocating a fourth series of even numbered frequency groups along a second and third layer of the second frequency reuse axis;

allocating a fifth series of odd numbered frequency groups along a first layer of a third frequency reuse axis; and

allocating a sixth series of even numbered frequency groups along a second and third layer of the third frequency reuse axis.

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

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

9. The method of claim 6 wherein the steps of allocating include allocating the frequencies in such a manner so as to create a first reuse distance in a first direction and a second reuse distance in a second direction.