Process to allocate channels in a sectorized and tiered cellular network

• US 8,195,172 B2
• Filed: 05/31/2002
• Issued: 06/05/2012
• Est. Priority Date: 04/03/2002
• Status: Active Grant

• Current Assignee: Illinois Institute of Technology
• Original Assignee: Illinois Institute of Technology
• Inventors: Frieder, Ophir, Nguyen, Vincent AnhDzung, Wan, Peng-Jun
• Primary Examiner(s): Daniel, Jr., Willie J
• Application Number:
  US10/160,481
• Publication Number:
  US 20030190918A1
• Time in Patent Office: 3,658 Days
• Field of Search: 455/450, 455/446, 455/447, 455/509, 455/63.4, 455/25, 370/329, 370/330, 709/226
• US Class Current: 455/450
• 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 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]

Abstract

The invention disclosed is a process to allocate channels in a sectorized and tiered cellular network. A system of allocating cellular frequencies (channels) to the sectors among the outer tier of cells within a tile is disclosed which maximizes channel set usage within the tile while minimizing co-channel interference between cells. Any unused, or remaining, frequencies for the outer tier of that cell may then be allocated to an inner tier of the cell that has not had a channel allocated thereto. No additional infrastructure or maintenance set-up is required under this technique for allocating the channel to the additional transceiver and a very high degree of channel utilization is achieved.

Claims

1. A method for allocation of channels by a cellular network operator to base stations, where each of the base stations is assigned within one of a plurality of base station cells of a tiered cellular communications system comprising:

a) indexing the base station cells within a cellular communications system according to rows and columns;

b) determining a co-channel interference requirement within the cellular communications system;

c) determining the number (N) of cell types required within the cellular communications system;

d) placing only one cell type in each row;

e) allocating channels to each base station of the base station cells according to;

i) allocate a distinct group of S+X channels for each cell type, where S is the number of sectors in an outer tier of a cell, and X is the number of channels needed to complete an alternation scheme,

ii) divide the S+X number of channels into rotating groups and alternating groups,

iii) designate which sector types of an outer tier of a cell receive members of the rotating group,

iv) designate which sector types of an outer tier of a cell receive members of the alternating group,

v) for a first row, first column cell;

allocate members of the rotating group into the designated rotating group sectors of the first row, first column cell, allocate at least one of the alternating group into the designated alternating group sector or sectors,

vi) for each succeeding cell in the row, rotate allocation of the members of the rotating group between or among the designated rotating sectors and alternate the allocation of members of the alternating group within the designated alternating group sector or sectors, and

vii) for an unallocated tier within a cell, allocate an unused member of the alternating group for that cell to the unallocated tier; and

f) operating each of the base stations according to the allocated channels.

2. The method of claim 1 further comprising, allocating members of the alternating group so as to avoid front lobe co-channel interference.

3. The method of claim 1 wherein the alternating group comprises more than one unused member.

4. The method of claim 3 wherein there is more than one unallocated tier within a cell for receiving an unused member of the alternating group.

5. The method of claim 1, wherein each of the base stations comprises directional antennae, and further comprising assigning one of the allocated channels to each of the directional antennae.

6. The method of claim 5, wherein each of the directional antennae receives radio frequencies of the corresponding allocated channel.

7. A method for allocation of channels to base stations within a tiered cellular communications system, wherein a geographic area serviced by the cellular communications system is divided into a plurality of cells, and each of the cells is associated with one of the base stations, and each of the base stations includes at least one antennae and has at least one assigned channel, the method comprising:

a) indexing the base stations (BS) within a cellular communications system according to rows and columns;

b) determining a co-channel interference requirement within the cellular communications system;

c) determining the number (N) of cell types required within the cellular communications system based on a co-channel interference requirement;

d) placing only one cell type in each row;

e) allocating channels to each base station of the plurality of cells according to;

i) allocate a distinct group of S+X channels for each cell type, where S is the number of sectors in an outer tier of a cell, and X is the number of channels needed to complete an alternation scheme providing sufficient separation between co-channels,

ii) divide the S+X number of channels into rotating groups and alternating groups,

iii) designate which sector types of the outer tier of a cell receive members of the rotating group,

iv) designate which sector types of the outer tier of a cell receive members of the alternating group,

v) for a first row, first column cell;

allocate members of the rotating group into the designated rotating group sectors of the first row, first column cell,

allocate at least one of the alternating group into the designated alternating group sector or sectors,

vi) allocate S of the channels from the cell type distinct group to an outer tier of a cell, subject to;

A) if any of the allocated group of S channels can be rotated to avoid front lobe interference with its nearest co-channel cell, rotate those channels, and

B) if A) cannot be accomplished, alternate a group of channels selected from S+X, and

vii) allocate an unused remaining member of the alternating group from S+X to an inner tier of the cell, and

f) operating each of the base stations according to the allocated channels.

8. The method of claim 7, wherein each of the base stations comprises directional antennae, and further comprising assigning one of the allocated channels to each of the directional antennae.

9. The method of claim 8, wherein each of the directional antennae receives radio frequencies of the corresponding allocated channel.

10. A method for allocation of channels by a cellular network operator to base stations within the cells of a tile for reuse within a cellular communications system comprising:

a) indexing the base stations (BS) within a cellular communications system according to a row (i) and a column (j);

b) determining a co-channel interference requirement within the cellular communications system;

c) determining the number (N) of cell types required within the cellular communications system;

d) allocating ordinals to each of the number of cell types and setting CurrentCellType to the cell type first in sequence;

e) labeling the cells by cell type according to;

i) if N is even;

ii) step 1;

label cells BS_i,j, BS_i,j+2, BS_i+N,j, and BS_i+N,j+2 as CurrentCellType,

iii) step 2;

increase i by 1,

change CurrentCellType to the cell type next in sequence,

if the ordinal of CurrentCellType is even set j=j+1, if ordinal is odd set j=j−

1,

iv) Step 3;

repeat from e) ii) step 1 for all cell types of the tile;

v) if N is odd;

vi) step 1;

label cells BS_i,j, BS_i,j+2 as CurrentCellType,

if the ordinal of CurrentCellType is odd, label BS_i+N,j+1 and BS_i+N,j+3 with CurrentCellType

if the ordinal of CurrentCellType is even, label BS<sub>i+N,j−

1</sub> and BS_i+N,j+1 with CurrentCellType,

vii) step 2;

increase i by 1,

change CurrentCellType to the cell type next in sequence,

if the ordinal of CurrentCellType is even set j=j+1, if ordinal is odd set j=j−

1,

viii) Step 3;

repeat from e) vi) step 1 for all cell types of the tile;

f) allocating channels to each cell according to;

allocate a distinct group of S+X channels for each cell type, where S is the number of sectors in an outer tier of a cell, and X is the number of channels needed to complete an alternation scheme providing sufficient separation between co-channels,

then for each cell;

allocate S of the channels from the cell type distinct group to an outer tier of a cell, subject to;

i) if any of the allocated group of S channels can be rotated to avoid front lobe interference with its nearest co-channel cell, rotate those channels,

ii) if i) cannot be accomplished, alternate a group of channels selected from S+X, and

iii) allocate an unused remaining member of the alternating group from S+X to an inner tier of the cell; and

g) operating each of the base stations according to the allocated channels.

11. The method of claim 10, wherein each of the base stations comprises directional antennae, and further comprising assigning one of the allocated channels to each of the directional antennae.

12. The method of claim 11, wherein each of the directional antennae receives radio frequencies of the corresponding allocated channel.

13. A method for allocation of frequency channels by a cellular network operator to base stations within a tiered cellular communications system, wherein a geographic area serviced by the cellular communications system is divided into a plurality of cells, and each of the cells is associated with one of the base stations, and each of the base stations includes at least one antennae and has at least one assigned frequency channel, the method comprising:

a) indexing the base stations (BS) within a cellular communications system according to a row (i) and a column (j);

b) determining a co-channel interference requirement within the cellular system;

c) determining the number (N) of cell types required within the cellular communications system;

d) sequentially identifying the cell types and setting CurrentCellType to the cell type first in sequence;

e) labeling the cells by cell type according to;

i) if N is even;

ii) step 1;

label cells BS_i,j, BS_i,j+2, BS_i+N,j, and BS_i+N,j+2 as CurrentCellType,

iii) step 2;

increase i by 1,

change CurrentCellType to the cell type having the ordinal next in sequence,

if the ordinal of CurrentCellType is even set j=j+1, if ordinal is odd set j=j−

1,

iv) Step 3;

repeat from e) ii) step 1 for all cell types of the tile;

v) if N is odd;

vi) step 1;

label cells BS_i,j, BS_i,j+2 as CurrentCellType,

if the ordinal of CurrentCellType is odd, label BS_i+N,j+1 and BS_i+N,j+3 with CurrentCellType

if the ordinal of CurrentCellType is even, label BS<sub>i+N,j−

1</sub> and BS_i+N,j+1 with CurrentCellType,

vii) step 2;

increase i by 1,

change CurrentCellType to the cell type having the ordinal next in sequence,

if the ordinal of CurrentCellType is even set j=j+1, if ordinal is odd set j=j−

1,

viii) Step 3;

repeat from e) vi) step 1 for all cell types of the tile;

f) allocating channels to each cell according to;

allocate a distinct group of S+X channels for each cell type, where S is the number of sectors in an outer tier of a cell, and X is the number of channels needed to complete an alternation scheme meeting the co-channel interference requirement,

then for each cell;

designate sectors a, b, and c to an outer tier of a cell,

allocate S of the channels from the cell type distinct group to an outer tier of a cell, subject to;

select a rotating group of channels from S+X,

select an alternating group of channels from S+X,

rotate members of the rotating group sectors a and b when a cell is in another column in the same row,

alternate members of the alternating group in sector c when a cell is in another column in the same row,

when changing to a new row make the rotating group of the previous row the alternating group for the new row and make the alternating group of the previous row the rotating group for the new row,

placing the new row alternating channel to minimize co-channel front lobe interference, and

allocating any unused members of the alternating group of channels of a cell to any tiers of that cell which have not had a channel allocated thereto; and

g) operating each of the base stations according to the allocated channels.

14. The method of claim 13 wherein N is an integer selected from the group comprising 1-7.

15. The method of claim 13 wherein S is an integer selected from the group comprising 3, 4, and 6.

16. The method of claim 13 wherein X=1.

17. The method of claim 13 wherein X=2.

18. The method of claim 13 wherein X=4.

19. The method of claim 13 wherein X is less than or equal to S.

20. The method of claim 13, wherein each of the base stations comprises directional antennae, and further comprising assigning one of the allocated channels to each of the directional antennae, wherein each of the directional antennae receives radio frequencies of the corresponding allocated channel.