System and method for management of neighbor-channel interference with cellular reuse partitioning

• US 6,181,918 B1
• Filed: 12/29/1995
• Issued: 01/30/2001
• Est. Priority Date: 12/29/1995
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Benveniste, Mathilde
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): Bhattacharya, Sam
• Application Number:
  US08/580,568
• Time in Patent Office: 1,859 Days
• Field of Search: 455/33.1, 455/33.3, 455/33.4, 455/54.1, 455/56.1, 455/63, 455/34.1, 455/422, 455/432, 455/447, 455/449, 455/452, 455/453, 455/450, 455/517, 455/524
• US Class Current: 455/63.2
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning

Abstract

A novel methodology is provided for managing neighbor channel interference in a cellular wireless communications system as a function of a service-quality factor for a communications channel within such a system. That methodology is characterized as Re-Use Partitioning with Neighbor-Channel Restrictions, and carries out the function of eliminating neighbor-channel interference between neighboring omni-directional cells.

Claims

1. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells, wherein a second plurality of communications channels are available for allocation among said cells, said method comprising the steps of:

forming two server groups in each cell, an inner server group for mobile units within a radius l from a central transmitting site in said cell, and an outer server group for mobile units outside that radius;

allocating said available channels among said server groups subject to the following constraints;

adjacent channels are not permitted in any (outer or inner) server group; and

adjacent channels cannot be used by any two outer server groups that are assigned to abutting cells.

2. The method of managing interference of claim 1 wherein said radius l is chosen such that a mobile unit inside that radius will not experience down-link adjacent channel interference from a neighboring cell.

3. The method of managing interference of claim 1 wherein said radius l is chosen such that a mobile unit inside that radius will not cause up-link adjacent channel interference to a mobile unit operating in a neighboring cell.

4. The method of managing interference of claim 1 wherein said radius l is defined by the relation:

$l=\frac{\sqrt{3}<br><br>R}{1+P_a^{-1/\mathrm{\gamma <br><br>}}}$

where P_a is a predefined threshold value for a received signal strength ratio relating a served mobile unit and an interfering mobile unit, R is the cell radius and γ

is a propagation loss coefficient.

5. The method of managing interference of claim 1 wherein re-use partitioning is applied to provide a higher traffic handling capacity for a cell.

6. The method of managing interference of claim 5 wherein said radial distance l from said central transmitting site is adjusted to effect a tradeoff between a realized Signal to Interference (S/I) ratio and a traffic carrying capacity for said cell.

7. The method of managing interference of claim 5 wherein said outer server group is characterized by a re-use factor of 9 and said inner server group is characterized by a re-use factor of 3.

8. The method of managing interference of claim 5 wherein said outer server group is characterized by a re-use factor of 8 and said inner server group is characterized by a re-use factor of 3 and channel sets are constructed by an odd/even method.

9. The method of managing interference of claim 1 wherein said method is applied for regular fixed channel assignment.

10. The method of managing interference of claim 1 wherein said method is applied for non-regular fixed channel assignment.

11. The method of managing interference of claim 1 wherein said method is applied for dynamic channel assignment.

12. A storage means fabricated to contain a model for determining an allocation of a plurality of communications channels among a second plurality of cells in a wireless communications network, said model carrying out the steps of the method for determining such an allocation of claim 1.

13. A method of managing interference of claim 7 wherein the radius l and the allocation of channels to server groups are determined so that the inner and outer server groups of a cell experience the same blocking rate.

14. A method of managing interference of claim 8 wherein the radius l and the allocation of channels to server groups are determined so that the inner and outer server groups of a cell experience the same blocking rate.