System and method for management of neighbor-channel interference with power control and directed channel assignment

• US 5,787,352 A
• Filed: 12/29/1995
• Issued: 07/28/1998
• 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): Chin, Tommy P.
• Assistant Examiner(s): Le, Vu
• Application Number:
  US08/581,694
• Time in Patent Office: 942 Days
• Field of Search: 455/33.1, 455/13.1, 455/34.1, 455/63, 455/296, 455/38.3, 455/62, 455/69, 455/295, 455/446-452, 455/443, 379/59
• US Class Current: 455/452.2
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

In a channel assignment system novel methodologies are utilized for managing channel interference in a cellular wireless communications system as a function of a service-quality factor for a communications channel within such a system. Those methodologies and their essential functions include: (1) Mixed Power Control for overcoming interference problems associated with conventional power control methods; (2) Directed Assignment for reducing channel conflicts between neighboring cells in non-congestion conditions; and (3) Mixed Power Control with Directed Assignment for reducing channel interference between neighboring cells.

Claims

1. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells;

wherein a plurality of communications channels are available for allocation among said cells said method comprising the steps of;

causing each of said available channels to be assigned a label corresponding to one of at least two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells in conjunction with an application of power control wherein high power users are assigned to low number channels in a first set of labeled cells and to high-number channels in a second set of labeled cells.

2. The method of managing interference of claim 1 wherein said step of causing channels to be assigned is carried out by distributing said available channels among a plurality of channel sets so that each set is assigned a label corresponding to said one of at least two mutually disjoint categories, and whereby no two sets with adjacent channels are labelled with a same category.

3. The method of managing interference of claim 2 wherein said step of causing cells to use commonly labeled channels is carried out by causing each said cell to use channels selected only from one or more of said channel sets assigned a common label.

4. A storage means fabricated to contain a model for managing interference in a wireless communications network, said model carrying out essentially the steps of the method for managing such interference of claim 1.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest-number channel available, and for cells with a label corresponding to a second of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label;

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest-number channel available, and for cells with a label corresponding to a second of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available;

assigning channels to users in each one of said cells in conjunction with an application of power control for transmissions to and from mobile units served by a central transmission site subject to the following constraints;

for transmissions from a central transmission site to a mobile unit ("down-link") said power control is applied only as to mobile users located beyond a distance from said transmission site; and

for transmissions from a mobile unit to a central transmission site ("up-link") said power control is applied only as to mobile units located within a radial distance for said central transmission site;

wherein each said radio distance is determined so as to achieve an acceptable level of interference and is utilized in the assignment of high power users to low-number channels in said first labeled cells and to high-number channels in said second labeled calls.

7. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells;

wherein a plurality of communications channels are available for allocation among said cells, said method comprising the steps of;

causing each of said available channels to be assigned a label corresponding to one of at least two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells in conjunction with an application of power control wherein high power users are assigned to low number channels in a first set of labeled cells and to high-number channels in a second set of labeled cells; and

further assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s base station, subject to a constraint that for cells with a label corresponding to a first of one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest-number channel available, and for cells with a label corresponding to a second one of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available.

8. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells;

wherein a plurality of communications channels are available for allocation among said cells, said method comprising the steps of;

causing each of said available channels to be assigned a label corresponding to one of at least two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label;

assigning said channels to users in each of said cells in conjunction with an application of power control wherein power control is applied for downlink transmissions from a central transmission site only to mobile units located beyond a radial distance from said central transmission site, said radial distance being determined so as to achieve an acceptable level of interference; and

wherein high power users are assigned to low number channels in a first set of labeled cells and to high-number channels in a second set of labeled cells.

9. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells;

wherein a plurality of communications channels are available for allocation among said cells, said method comprising the steps of;

causing each of said available channels to be assigned a label corresponding to one of at least two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label;

assigning said channels to users in each of said cells with an application of power control wherein power control is applied for uplink transmissions from a mobile unit to a central transmission site only to mobile units located within a radial distance from said central transmission site, said radial distance being determined so as to achieve an acceptable level of interference; and

wherein high power users are assigned to low number channels in a first set of labeled cells and to high-number channels in a second set of labeled cells.

10. A method of managing interference in a wireless communications network having service areas partitioned into a plurality of cells;

wherein a plurality of communications channels are available for allocation among said cells, said method comprising the steps of;

causing each of said available channels to be assigned a label corresponding to one of at least two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells in conjunction with an application of power control wherein high power users are assigned to low number channels in a first set of labeled cells and to high-number channels in a second set of labeled cells; and

further

rearranging the channel assignments within a cell upon a departure of a mobile unit from said cell by method steps used in the initial channel assignments.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest number channel available and for cells with a label corresponding to a second one of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available and assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s serving base station, starting at an end of the spectrum opposite the one end of the assigned spectrum.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest number channel available and for cells with a label corresponding to a second one of said mutually disjoint categories, a label corresponding to a second of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available and assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s serving base station, starting at an end of the spectrum opposite the one end of the assigned spectrum, and the assigning of channels being carried out by distributing said available channels among a plurality of channel sets so that each one of said sets is assigned a label corresponding to said one of two mutually disjoint categories, and whereby no two sets with adjacent channels are labeled with a same category.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest number channel available and for cells with a label corresponding to a second one of said mutually disjoint categories, a label corresponding to a second of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available and assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s serving base station, starting at an end of the spectrum opposite the one end of the assigned spectrum, and the assigning of channels being carried out by distributing said available channels among a plurality of channel sets so that each one of said sets is assigned a label corresponding to said one of two mutually disjoint categories, and whereby no two sets with adjacent channels are labeled with a same category, and wherein the step of causing cells to use commonly labeled channels is carried out by causing each of said cells to use channels selected only from one or more of said channel sets assigned a common label.

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

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest number channel available and for cells with a label corresponding to a second one of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available and assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s serving base station, starting at an end of the spectrum opposite the one end of the assigned spectrum, and the assigning of channels being carried out by distributing said available channels among a plurality of channel sets so that each one of said sets is assigned a label corresponding to said one of two mutually disjoint categories, and whereby no two sets with adjacent channels are labeled with a same category; and

rearranging the channel assignments within a cell upon a departure of a mobile unit from said cell by method steps used in the initial channel assignments.

15. A storage means fabricated to contain a model for managing interference in a wireless communications network said model having instructions for having service areas partitioned into a plurality of cells, wherein a plurality of communications channels are available for allocation among said cells, said method comprising the steps of:

causing each of said available channels to be assigned a label corresponding to one of two mutually disjoint categories, wherein no two adjacent channels are labeled with a same category;

causing each of said cells to use channels that have been assigned a common label; and

assigning said channels to users in each of said cells according to a constraint that, for cells with a label corresponding to a first one of said mutually disjoint categories, said cells'"'"' users are assigned to a lowest number channel available and for cells with a label corresponding to a second one of said mutually disjoint categories, said cells'"'"' users are assigned to a highest-number channel available and assigning channels to users in each cell in order of decreasing distance from each of said user'"'"'s serving base station, starting at an end of the spectrum opposite the one end of the assigned spectrum.