METHOD OF TRANSMITTING PILOT TONES IN A MULTI-SECTOR CELL, INCLUDING NULL PILOT TONES, FOR GENERATING CHANNEL QUALITY INDICATORS

• US 20070213087A1
• Filed: 05/14/2007
• Published: 09/13/2007
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Fan, John
• Granted Patent: US 9,603,102 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 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. 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.

9. The method of claim 8, wherein the first and third pre-selected amounts of transmission power are non-zero and are the same.

10. 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.

11. The apparatus of claim 10, 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.

12. The method of claim 11, wherein said second pre-selected transmission power and said third pre-selected transmission power are the same.