Adaptive power level tiered cellular mobile communications systems

• US 6,370,383 B1
• Filed: 09/14/1999
• Issued: 04/09/2002
• Est. Priority Date: 09/14/1999
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Leatham, Marcus C., Richardson, Regena L., Eswara, Srinivas
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/395,662
• Time in Patent Office: 938 Days
• Field of Search: 455/446, 455/447, 455/449, 455/450, 455/451, 455/452, 455/453, 455/422, 455/63
• US Class Current: 455/446
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/32 Hierarchical cell structures

Abstract

An adaptive power tiered cell includes inner and outer tiers. Each one of a plurality of communication channels for servicing mobile terminals operating within the cell is assigned to either the inner tier or the outer tier. When a switch of one of the channels assigned to serve mobile terminals operating in a first one of the inner and outer tiers to serving mobile terminals operating in the other one of the first and second tiers is detected, the inner at tier is re-sized such that a ratio of the area of the first tier to the area of the cell matches a ratio of the number of channels serving mobile terminals operating in the inner tier to the number of channels serving mobile terminals operating in the cell. To re-size the inner tier such that a ratio of the area of the inner tier to the area of the cell matches a ratio of the number of channels serving mobile terminals operating in the inner tier to the number of channels serving mobile terminals operating in the cell, a power level threshold value which defines an outer peripheral edge of the inner tier is adjusted.

Claims

1. A power level tiered cellular telephone system having a cell divided into first and second tiers, comprising:

a base station, said base station including a plurality of radio transceivers, each configured for serving mobile terminals within said cell and assigned to a selected one of said first and second tiers of said cell for serving mobile terminals operating therein;

said base station assigning each mobile terminal served within said cell to one of said first and second tiers based upon a power level for said mobile terminal relative to a power level threshold boundary; and

a controller coupled to each one of said plurality of radio transceivers, said controller periodically shifting said power level threshold boundary defining an outer peripheral edge for said first tier of said cell based upon a change in a operating condition within said cell.

2. The power level tiered cellular telephone system according to claim 1 wherein said operating condition is a ratio of the number of radio transceivers serving said first tier to the number of radio transceivers serving said cell.

3. The power level tiered cellular telephone system according to claim 1 wherein said operating condition is a ratio of the number of channels serving said inner tier and the number of channels serving said cell.

4. The power level tiered cellular telephone system according to claim 1 wherein each one of said plurality of radio transceivers is a dynamic radio transceiver capable of changing which one of said first and second tiers are served thereby.

5. The power level tiered cellular telephone system according to claim 1 and further comprising:

an intelligent cellular peripheral coupled to said base station;

said controller residing at said intelligent cellular peripheral.

6. The power level tiered cellular telephone system according to claim 5 and further comprising;

a mobile switching center coupled to said intelligent cellular peripheral.

7. A power level tiered cellular telephone system having a cell, said power level tiered cellular telephone system serving mobile terminals operating within said cell, said cell divided into an inner tier and an outer tier, said mobile terminals operating in said outer tier experiencing lower levels of interference than if operating in said inner tier, said power level tiered cellular telephone system comprising:

a base station, said base station including a plurality of dynamic radio transceivers and an antenna array coupled to each one of said plurality of dynamic radio transceivers, each one of said plurality of dynamic radio transceivers configured for serving mobile terminals within said cell and assigned to a selected one of said inner and outer tiers of said cell for serving mobile terminals operating therein;

an intelligent cellular peripheral having a processor subsystem on which a first software module executes, said intelligent cellular peripheral coupled to said base station;

a mobile switching center having a processor subsystem on which a second software module executes, said mobile switching center coupled to said intelligent cellular peripheral;

said first software module configured for assigning each one of said mobile terminals to a selected one of said radio transceivers based upon a power level for said mobile terminal when said mobile terminal initiates operations within said cell relative to a power level threshold boundary which defines a peripheral edge of said outer tier and periodically re-determining said power level threshold boundary separating said inner and outer tiers of said cell each time one of said plurality of radio transceivers switches from serving mobile terminals operating in one of said inner and outer tiers to serving mobile terminals operating in the other of said inner and outer tiers.

8. The power level tiered cellular telephone system according to claim 7 wherein said intelligent cellular peripheral further comprises a memory subsystem accessible by said first software module, said memory subsystem maintaining a list of said plurality of dynamic radio transceivers, an indicator as to which tier each one of said plurality of dynamic radio transceivers serve and an indicator as to available channels for each one of said plurality of dynamic radio transceivers serving said inner tier or serving said outer tier.

9. The power level tiered cellular telephone system according to claim 7 wherein said second software module is a call processing module.

10. The power level tiered cellular telephone system according to claim 7 wherein said cell is divided into at least two sectors, each having a sector inner tier, a sector outer tier and a sector power level threshold boundary which defines an outer peripheral edge of said sector inner tier and where said antenna array comprises at least two directional antennas, each providing coverage for a corresponding sector of said cell and said plurality of dynamic radio transceivers are assigned to a selected one of said sector inner tier and said sector outer tier of a selected one of said at least two sectors.

11. The power level tiered cellular telephone system according to claim 10 wherein said first software module periodically re-determines said power level threshold defining said outer peripheral edge of said sector inner tier for a first one of said at least two sectors of said cell each time one of said plurality of radio transceivers serving said first one of said at least two sectors of said cell switches from serving mobile terminals operating in one of said sector inner tier and said sector outer tier for said sector to serving mobile terminals operating in the other of said sector inner tier and said sector outer tier for said sector.

12. A method of adaptively power tiering a cell of a cellular telephone system, comprising the steps of:

selecting a value for a mobile proximity threshold boundary;

separating said cell into first and second tiers, each having a respective size, said first tier having an outer peripheral edge defined by said mobile proximity threshold boundary and said second tier having an outer peripheral edge defined by a boundary for said cell;

periodically re-determining said value for said mobile proximity threshold boundary; and

re-sizing said first tier each time that said value for said mobile proximity threshold boundary changes.

13. The method of adaptively power tiering a cell of a cellular telephone system according to claim 12 wherein said value for said mobile proximity threshold is re-determined upon detecting a change in an operating condition for said cellular telephone system.

14. The method of adaptively power tiering a cell of a cellular telephone system according to claim 12 wherein said cell is served by a plurality of dynamic radio transceivers and wherein the step of periodically re-determining said value for said mobile proximity threshold boundary further comprises the steps of:

initially assigning each one of said plurality of dynamic radio transceivers for serving mobile terminals operating in said cell to a selected one of said first and second tiers, respectively; and

re-determining said value for said mobile proximity threshold boundary each time one of said plurality of dynamic radio transceivers changes from serving mobile terminals operating in one of said first and second tiers to serving mobile terminals operating in the other of said first and second tiers.

15. A method of adaptively power tiering a cell of a cellular telephone system, comprising the steps of:

providing a plurality of radio transceivers to serve mobile terminals operating in said cell;

dividing said cell into first and second power tiers, said first power tier having an area;

assigning each one of said plurality of radio transceivers to a selected one of said first and second power tiers of said cell, each one of said plurality of radio transceivers assigned to said first power tier of said cell serving mobile terminals operating in said first power tier of said cell and each one of said plurality of radio transceivers assigned to said second power tier of said cell serving mobile terminals operating in said second power tier of said cell;

adjusting said area of said first power tier each time one of said plurality of radio transceivers serving mobile terminals operating in one of said first and second power tiers switches to serving mobile terminals operating in the other one of said first and second power tiers.

16. The method of adaptively power tiering a cell of a cellular telephone system according to claim 15 wherein said first power tier has a first area, said cell has a second area and further comprising the step of:

determining a ratio of the number of radio transceivers assigned to said first power tier of said cell to said area of said first power tier of said cell.

17. The method of adaptively power tiering a cell of a cellular telephone system according to claim 16 wherein the step of adjusting said area of said first power tier each time one of said plurality of radio transceivers serving mobile terminals operating in one of said first and second power tiers switches to serving mobile terminals operating in the other one of said first and second power tiers further comprises the step of:

adjusting said area of said first power tier to maintain said ratio of the number of radio transceivers assigned to said first power tier of said cell to said area of said first power tier of said cell.

18. The method of adaptively power tiering a cell of a cellular telephone system according to claim 15 wherein said first power tier is an inner tier, said second power tier is an outer tier and further comprising the steps of:

determining a ratio of the number of radio transceivers assigned to said inner tier of said cell to the number of radio transceivers assigned to said cell; and

determining a ratio of the square of the radius of said inner tier to the square of the radius of said cell.

19. The method of adaptively power tiering a cell of a cellular telephone system according to claim 18 wherein the step of adjusting said area of said first power tier each time one of said plurality of radio transceivers serving mobile terminals operating in one of said first and second power tiers switches to serving mobile terminals operating in the other one of said first and second power tiers further comprises the steps of:

each time one of said plurality of radio transceivers serving mobile terminals operating in one of said inner and outer tiers switches to serving mobile terminals operating in the other one of said inner and outer tiers, re-determining a ratio of the number of radio transceivers assigned to said inner cell to the number of radio transceivers assigned to said cell;

re-determining the radius of said inner tier such that said ratio of the square of the radius of said inner tier to the square of the radius of said cell equals said of the number of radio transceivers assigned to said inner tier to the number of radio transceivers in said cell remains constant; and

re-tiering said power tiered cell in accordance with said re-determined radius of said inner tier of said cell.

20. For a cellular telephone system having a power tiered cell which includes an inner tier and an outer tier, a method for servicing mobile terminals operating within said power tiered cell using a plurality of communication channels, said method comprising the steps of:

assigning each one of said plurality of communication channels to either said inner tier or said outer tier;

determining whether a first mobile terminal to be served is operating in said inner tier or said outer tier;

if said first mobile terminal is operating in said inner tier, providing service to said first mobile terminal over an available channel of said channels assigned to serve mobile terminals operating in said inner tier;

if said first mobile terminal is operating in said outer tier, providing service to said first mobile terminal over an available channel of said channels assigned to serve mobile terminals operating in outer tier;

detecting a switch of one of said channels assigned to serve mobile terminals operating in a first one of said inner and outer tiers to serving mobile terminals operating in the other one of said inner and outer tiers;

upon detecting said switch, re-sizing said inner tier such that a ratio of the area of said inner tier to the area of said cell matches a ratio of the number of channels serving mobile terminals operating in said inner tier to the number of channels serving mobile terminals operating in said cell;

determining whether a next mobile terminal to be served is operating in said inner tier or said outer tier;

if said next mobile terminal is operating in said inner tier, providing service to said next mobile terminal over a next available one of said channels assigned to serve mobile terminals operating in said inner tier; and

if said next mobile terminal is operating in said outer tier, providing service to said next mobile terminal over a next available one of said channels assigned to serve mobile terminals operating in said outer tier;

wherein, by re-sizing said inner tier, said inner tier and said cell maintain a constant density of assigned channels per unit area.

21. The method of servicing terminals according to claim 20 wherein the step of determining whether a first mobile terminal to be served is operating in said inner tier or said outer tier further comprises the steps of:

determining a power level threshold value which defines an outer peripheral edge of said inner tier;

determining a power level for said first mobile terminal; and

comparing said power level for said first mobile terminal to said power level threshold value to determine whether said first mobile terminal is operating in said inner tier or said outer tier.

22. The method of servicing terminals according to claim 21 wherein the step of re-sizing said inner tiers such that a ratio of the area of said inner tier to the area of said cell matches a ratio of the number of channels serving mobile terminals operating in said inner tier to the number of channels serving mobile terminals operating in said cell further comprises the step of:

adjusting said power level threshold value defining said outer peripheral edge of said inner tier such that said ratio of the area of said inner tier to the area of said cell matches said ratio of the number of channels serving mobile terminals operating in said inner tier to the number of channels serving mobile terminals operating in said cell.

23. The method of servicing terminals according to claim 22 wherein the step of determining whether a next mobile terminal to be served is operating in said inner tier or said outer tier further comprises the steps of:

determining a power level for said next mobile terminal; and

comparing said power level for said next mobile terminal to said adjusted power level threshold value to determine whether said next mobile terminal is operating in said inner tier or said outer tier.