Pilot signals for use in multi-sector cells

• US 20040166886A1
• Filed: 08/25/2003
• Published: 08/26/2004
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Fan, John L.
• Granted Patent: US 7,218,948 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

Pilot signal transmission sequences and methods are described for use in a multi-sector cell. Pilots in different sectors are transmitted at different known power levels. In adjacent sectors a pilot is transmitted while no pilot is transmitted in the adjoining sector. This represents transmission of a NULL pilot signal. A cell NULL is also supported in which NULL pilots are transmitted in each sector of a cell at the same time. Multiple pilot signal measurements are made. At least two channel quality indicator values are generated from measurements corresponding to at least two pilot signals of different power levels. The two values are transmitted back to the base station which uses both values to determine the transmit power required to achieve a desired SNR at the wireless terminal. The wireless terminal also reports information indicating its location to a sector boundary.

Claims

1. A method of transmitting pilot tones in a multi-sector cell including at least a first sector and a second sector, the second sector being located adjacent said first sector, the method comprising:

transmitting, using a first tone, in said first sector during a first symbol time a first pilot signal having a first pre-selected transmission power; and

transmitting, using said first tone, in said second sector during a second symbol time, which overlaps said first symbol time, a second pilot signal having a second pre-selected transmission power which is different from said first pre-selected transmission power.

2. The method of claim 1, wherein the second pre-selected transmission power is zero, said second pilot being a NULL pilot signal.

3. The method of claim 1, further comprising:

transmitting, using a second tone, in said first sector during a third symbol time a third pilot signal having a third pre-selected transmission power; and

transmitting, using said second tone, in said second sector during a fourth symbol time, which overlaps said third symbol time, a fourth pilot signal having a fourth pre-selected transmission power which is different from said third pre-selected transmission power.

4. The method of claim 3, wherein said second pre-selected transmission power and said third preselected transmission power are the same.

5. The method of claim 4, wherein said second pre-selected transmission power is zero, said second and third pilot signals being NULL pilot signals.

6. The method of claim 1,

wherein said first and third symbol times are the same;

and

wherein said first and second tones are different.

7. The method of claim 1,

wherein said first and third symbol times do not overlap;

and

wherein said first and second tones are the same.

8. The method of claim 3, wherein further comprising:

transmitting, using a third tone, in said first sector during a fifth symbol time a fifth pilot signal having a fifth pre-selected transmission power; and

transmitting, using said third tone, in said second sector during a sixth symbol time, which overlaps said fifth symbol time, a sixth pilot signal having said fifth pre-selected transmission power.

9. The method of claim 8, wherein said second, third and fifth pre-selected transmission powers are the same.

10. The method of claim 9, wherein said second pre-selected transmission power is zero, the second, third, fifth and sixth pilot signals being NULL pilot signals.

11. The method of claim 8,

wherein said first, second, and third tones are the same;

and

wherein said first, third and fifth symbol times are different.

12. The method of claim 8,

wherein said first, third and fifth symbol times are the same;

and

wherein said first, second and third tones are different.

13. The method of claim 8, wherein said first, fourth and fifth pre-selected transmission powers are the same.

14. The method of claim 13,

wherein said first, fourth and fifth pre-selected transmission powers are non-zero;

and

wherein said second and third pre-selected transmission powers are zero.

15. The method of claim 8, further comprising:

periodically repeating each of said transmitting steps to form a pre-determined repeating sequence of said transmitting steps.

16. The method of claim 12, further comprising:

transmitting, using a fourth tone, in said first sector during a seventh symbol time a seventh pilot signal having a seventh pre-selected transmission power which is different from said fifth pre-selected transmission power; and

transmitting, using said fourth tone, in said second sector during an eighth symbol time, which overlaps said seventh symbol time, an eighth pilot signal having an eighth pre-selected transmission power which is the same as said seventh pre-selected transmission power.

17. The method of claim 16,

wherein said first, second, third and fourth tones are different;

and

wherein said first, third, fifth and seventh symbol times are the same.

18. The method of claim 16,

wherein the first, second, third and fourth tones are the same;

and

wherein said first, third, fifth and seventh symbol times are different.

19. The method of claim 16, wherein the first, fourth and sixth pre-selected transmission powers are the same.

20. The method of claim 19,

wherein the second, third and fifth pre-selected transmission powers are zero;

and

wherein the said first, third, fifth and seventh symbol times are the same.

21. The method of claim 16, further comprising:

repeating each of said transmitting steps according to a pre-selected repetition pattern.

22. The method of claim 1, wherein said multi-sector cell further includes a third sector, said third sector being located adjacent said second sector, the method further comprising:

transmitting, using said first tone, in said third sector during a ninth symbol time a ninth pilot signal, said ninth symbol time overlapping said first and second symbol times, said ninth pilot signal being transmitted with the same transmission power as said first pilot signal.

23. The method of claim 1, wherein said multi-sector cell further includes a third sector, said third sector being located adjacent said second sector, the method further comprising:

transmitting, using said first tone, in said third sector during a ninth symbol time a ninth signal, which is one of control and data pilot signal, said ninth symbol time overlapping said first and second symbol times.

24. The method of claim 22, further comprising:

transmitting, using said second tone, in said third sector during a tenth symbol time a tenth pilot signal, said tenth symbol time overlapping said third and fourth symbol times, said tenth pilot signal being transmitted with the same transmission power as said third pilot signal.

25. The method of claim 24, further comprising:

transmitting, using said third tone, in said third sector during an eleventh symbol time an eleventh pilot signal, said eleventh symbol time overlapping said fifth and sixth symbol times, said eleventh pilot signal being transmitted with an eleventh pre-selected transmission power that is the same as the fifth pre-selected transmission power used to transmit the fifth and sixth pilots.

26. The method of claim 25, further comprising:

periodically repeating each of said transmitting steps.

27. A method of transmitting pilot signals in a multi-sector cell, the multi-sector cell including at least first, second and third sectors, each of the first, second and third sectors being located adjacent at least one other one of said first, second and third sectors in said cell, the method comprising:

transmitting during at least a portion of a first symbol time;

a first pilot on a first tone in the first sector using a first pre-selected transmission power;

a second pilot signal on the first tone in the second sector using a second pre-selected transmission power which is different from said first pre-selected amount of transmission power; and

a third pilot signal on the first tone in the third sector using a third pre-selected amount of transmission power.

28. The method of claim 27, wherein the first and third pre-selected amounts of transmission power are non-zero and are the same.

29. The method of claim 28, further comprising:

transmitting during at least a portion of a second symbol time;

a fourth pilot on a second tone in the first sector using a fourth pre-selected amount of transmission power;

a fifth pilot on the second tone in the second sector using a fifth pre-selected amount of transmission power; and

a sixth pilot on the second tone in the third sector using said fifth pre-selected amount of transmission power.

30. The method of claim 29,

wherein said first and second symbol times are the same;

wherein said first, third and fourth pilot signals are transmitted with the same amount of power; and

wherein said second fifth and sixth pilot signals are NULL pilot signals transmitted with zero power.

31. The method of claim 29, further comprising:

transmitting during at least a portion of a third symbol time;

a seventh pilot on a third tone in the first sector using said first pre-selected amount of transmission power;

an eighth pilot on the third tone in the second sector using an eighth pre-selected amount of transmission power; and

a data symbol on the third tone in the third sector.

32. The method of claim 30, wherein the first, second and third tones are different and wherein the first second and third symbol times are the same.

33. An apparatus for transmitting pilot tones in a multi-sector cell, the apparatus comprising:

a transmitter;

means for controlling said transmitter to transmit, using a first tone, in said first sector during a first symbol time a first pilot signal having a first pre-selected transmission power; and

means for controlling said transmitter to transmit, using said first tone, in said second sector during a second symbol time, which overlaps said first symbol time, a second pilot signal having a second pre-selected transmission power which is different from said first pre-selected transmission power.

34. The apparatus of claim 33, further comprising:

means for controlling said transmitter to transmit, using a second tone, in said first sector during a third symbol time a third pilot signal having a third pre-selected transmission power; and

means for controlling said transmitter, using said second tone, in said second sector during a fourth symbol time, which overlaps said third symbol time, a fourth pilot signal having a fourth pre-selected transmission power which is different from said third pre-selected transmission power.

35. The method of claim 34, wherein said second pre-selected transmission power and said third pre-selected transmission power are the same.