Multiple access wireless communications system using a multi-sector configuration

• US 7,995,527 B2
• Filed: 05/13/2008
• Issued: 08/09/2011
• Est. Priority Date: 08/26/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Lane, Frank
• Primary Examiner(s): Moe; Aung S
• Assistant Examiner(s): Rose; Kerri M
• Application Number:
  US12/119,774
• Publication Number:
  US 20080291856A1
• Time in Patent Office: 1,183 Days
• Field of Search: 370/203, 370/208, 370/310, 370/328, 370/329, 370/330, 370/338, 370/343, 370/344, 370/311, 455/422.1, 455446-4522
• US Class Current: 370/329
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Power control methods and apparatus for use in a sectorized cell of an OFDM communications system are described. Each sector of a cell uses the same frequencies and transmission times and is synchronized with the other sectors in the cell in terms of tone frequencies used at any given time and symbol transmission times. Tones are allocated to channels in each cell in the same manner so that each channel in a sector has a corresponding channel in another sector. Power differences between channels in different sectors are maintained to be within a pre-selected power difference. Different channels in a cell are assigned different power levels. Wireless terminals are assigned to channels based on channel feedback information. Wireless terminals with poor channel conditions are allocated to higher power channels than wireless terminals with good channel conditions. Lower power channels often include more tones per symbol time than high power channels.

Claims

1. A method of operating a transmitter within a cell of a wireless communication system, the cell including a first sector adjoining a second sector, comprising:

transmitting different information into the first sector and the second sector, said transmitting different information including transmitting symbols on first and second communications channels in a synchronous manner, wherein;

the first and second communications channels include a respective first subset and second subset of a set of tones during each of a first subset and second subset of a plurality of symbol times; and

the first subset of the set of tones and the second subset of the set of tones are different from each other during each of the plurality of symbol times; and

controlling a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector during the first subset of the plurality of symbol times.

2. The method of claim 1, wherein the predetermined range is greater than 0.2 and less than 5 times the second total transmission power.

3. The method of claim 1, wherein the first total transmission power and the second total transmission power are no more than a fixed fraction of a maximum average total transmission power used when transmitting within the first sector during any 1 hour period.

4. The method of claim 3, wherein the fixed fraction is less than 100%.

5. The method of claim 1, further comprising:

prior to transmitting symbols in said first sector on the first channel, scrambling at least some symbols to be transmitted on the first channel in the first sector using a first scrambling sequence; and

prior to transmitting symbols in said second sector on the first channel, scrambling at least some of the symbols to be transmitted on the first channel in the second sector using a second scrambling sequence which is different from said first scrambling sequence.

6. The method of claim 5, wherein a lower end of said predetermined range is greater than 0.2 times the second transmission power level.

7. The method of claim 6, wherein a higher end of said predetermined range is less than 5 times the second transmission power level.

8. The method of claim 1,

wherein controlling a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector includes controlling the transmission power difference between signals transmitted on the first channel in the first and second sectors to be within a first dynamic range;

and

wherein the method further comprises;

controlling a transmission power difference between signals transmitted on said first and second channels within the first sector to be within a second dynamic range, said second dynamic range being greater than said first dynamic range.

9. An apparatus for operating a transmitter within a cell of a wireless communication system, the cell including a first sector adjoining a second sector, comprising:

means for transmitting different information into the first sector and the second sector, said means for transmitting different information transmitting symbols on first and second communications channels in a synchronous manner, wherein;

the first and second communications channels include a respective first subset and second subset of a set of tones during each of a first subset and second subset of a plurality of symbol times; and

the first subset of the set of tones and the second subset of the set of tones are different from each other during each of the plurality of symbol times; and

means for controlling a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector during the first subset of the plurality of symbol times.

10. The apparatus of claim 9, wherein the is greater than 0.2 and less than 5 times the second total transmission power.

11. The apparatus of claim 9, wherein the first total transmission power and the second total transmission power are no more than a fixed fraction of a maximum average total transmission power used when transmitting within the first sector during any 1 hour period.

12. The apparatus of claim 11, wherein the fixed fraction is less than 100%.

13. The apparatus of claim 9, further comprising:

means for scrambling at least some symbols to be transmitted in the first sector using a first scrambling sequence, prior to transmitting symbols in said first sector, and scrambling at least some of the symbols to be transmitted in the second sector using a second scrambling sequence which is different from said first scrambling sequence, prior to transmitting symbols in said second sector.

14. An apparatus for operating a transmitter within a cell of a wireless communication system, the cell including a first sector adjoining a second sector, comprising:

a transmitter configured to transmit different information into the first sector and the second sector, said transmitting different information including transmitting symbols on first and second communications channels in a synchronous manner, wherein;

the first and second communications channels include a respective first subset and second subset of a set of tones during each of a first subset and second subset of a plurality of symbol times; and

the first subset of the set of tones and the second subset of the set of tones are different from each other during each of the plurality of symbol times; and

a controller configured to control a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector during the first subset of the plurality of symbol times.

15. The apparatus of claim 14, wherein the predetermined range is greater than 0.2 and less than 5 times the second total transmission power.

16. The apparatus of claim 14, wherein the first total transmission power and the second total transmission power are no more than a fixed fraction of a maximum average total transmission power used when transmitting within the first sector during any 1 hour period.

17. The apparatus of claim 16, wherein the fixed fraction is less than 100%.

18. The apparatus of claim 14, further comprising:

a scrambling module configured to;

scramble at least some symbols to be transmitted in the first sector using a first scrambling sequence, prior to transmitting symbols in said first sector; and

scramble at least some of the symbols to be transmitted in the second sector using a second scrambling sequence which is different from said first scrambling sequence, prior to transmitting symbols in said second sector.

19. A computer-program product for operating a transmitter within a cell of a wireless communication system, the cell including a first sector adjoining a second sector, comprising a memory device having a set of instructions stored thereon, the set of instructions being executable by one or more processors and the set of instructions comprising:

instructions for transmitting different information into the first sector and the second sector, said transmitting different information including transmitting symbols on first and second communications channels in a synchronous manner, wherein;

the first and second communications channels include a respective first subset and second subset of a set of tones during each of a first subset and second subset of a plurality of symbol times; and

the first subset of the set of tones and the second subset of the set of tones are different from each other during each of the plurality of symbol times; and

instructions for controlling a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector during the first subset of the plurality of symbol times.

20. The computer-program product of claim 19, wherein the predetermined range is greater than 0.2 and less than 5 times the second total transmission power.

21. The computer-program product of claim 19, wherein the first total transmission power and the second total transmission power are no more than a fixed fraction of a maximum average total transmission power used when transmitting within the first sector during any 1 hour period.

22. The computer-program product of claim 21, wherein the fixed fraction is less than 100%.

23. The computer-program product of claim 19, wherein the set of instructions further comprises:

instructions for scrambling, prior to transmitting symbols in said first sector, at least some symbols to be transmitted in the first sector using a first scrambling sequence; and

instructions for scrambling, prior to transmitting symbols in said second sector, at least some of the symbols to be transmitted in the second sector using a second scrambling sequence which is different from said first scrambling sequence.

24. An apparatus for operating a transmitter within a cell of a wireless communication system, the cell including a first sector adjoining a second sector, comprising:

a processor configured to control said transmitter to;

transmit different information into the first sector and the second sector, said transmitting different information including transmitting symbols on first and second communications channels in a synchronous manner, wherein;

the first and second communications channels include a respective first subset and second subset of a set of tones during each of a first subset and second subset of a plurality of symbol times; and

the first subset of the set of tones and the second subset of the set of tones are different from each other during each of the plurality of symbol times; and

control a first total transmission power of the first subset of the set of tones transmitted into the first sector during the first subset of the plurality of symbol times to be within a predetermined range of a second total transmission power of the first subset of the set of tones transmitted into the second sector during the first subset of the plurality of symbol times; and

memory coupled to said processor.

25. The apparatus of claim 24, wherein the predetermined range is greater than 0.2 and less than 5 times the second total transmission power.