Pilots for MIMO communication systems

Patent metadata

Field	Value
Publication number	US-9312935-B2
Application number	US-201113155916-A
Country	US
Kind code	B2
Filing date	Jun 8, 2011
Priority date	Oct 25, 2002
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Pilots suitable for use in MIMO systems and capable of supporting various functions are described. The various types of pilot include—a beacon pilot, a MIMO pilot, a steered reference or steered pilot, and a carrier pilot. The beacon pilot is transmitted from all transmit antennas and may be used for timing and frequency acquisition. The MIMO pilot is transmitted from all transmit antennas but is covered with different orthogonal codes assigned to the transmit antennas. The MIMO pilot may be used for channel estimation. The steered reference is transmitted on specific eigenmodes of a MIMO channel and is user terminal specific. The steered reference may be used for channel estimation. The carrier pilot may be transmitted on designated subbands/antennas and may be used for phase tracking of a carrier signal. Various pilot transmission schemes may be devised based on different combinations of these various types of pilot.

First claim

What is claimed is:

1. In a user terminal for use in a wireless communication system supporting multiple-input multiple-output (MIMO) communications, a method comprising:
receiving a first pilot of a first type including information to facilitate system timing and frequency acquisition from an access point including a plurality of antennas;
receiving a second pilot of a second type different from the first type including information to facilitate channel estimation between said user terminal and the access point; and
generating a channel estimate from information in said second pilot,
wherein the first pilot is neither beamformed nor spatially multiplexed and the second pilot is one of beamformed using signal processing or spatially multiplexed, and
wherein the second pilot includes a steered pilot transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

2. The method of claim 1 , wherein the second pilot includes user specific information.

3. The method of claim 1 , further comprising:
receiving a third pilot including user specific information and a first cover code from a first one of said plurality of antennas at the access point; and
receiving a fourth pilot including user specific information and a second cover code from a second one of said plurality of antennas at the access point,
wherein the first and second cover codes are orthogonal cover codes.

4. The method of claim 3 , wherein the orthogonal cover codes comprise Walsh codes.

5. The method of claim 3 , further comprising generating a MIMO channel estimate from information in the third and fourth pilots.

6. The method of claim 3 , wherein the third and fourth pilots comprise MIMO pilots.

7. The method of claim 6 , wherein each of the MIMO pilots includes a pilot that was transmitted from each of the plurality of antennas at the access point with different orthogonal codes.

8. The method of claim 1 , wherein the first pilot comprises a beacon pilot.

9. The method of claim 8 , wherein the beacon pilot includes a specific set of pilot symbols that was transmitted from each of the plurality of antennas at the access point.

10. The method of claim 1 , wherein the second pilot comprises a steered pilot.

11. In an access point including a plurality of antennas for use in a wireless communications system supporting multiple-input multiple-output (MIMO) communications, a method comprising:
generating a plurality of pilots, said plurality of pilots including:
a first pilot of a first type including information to facilitate system timing and frequency acquisition, and
a second pilot of a second type different from the first type including information to facilitate channel estimation between said access point and at least one user terminal; and
transmitting said plurality of pilots to said at least one user terminal,
wherein the first pilot is neither beamformed nor spatially multiplexed and the second pilot is one of beamformed using signal processing or spatially multiplexed, and
wherein the second pilot includes a steered pilot transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

12. The method of claim 11 , further comprising:
receiving a channel estimate from said at least one user terminal based on information in the second pilot.

13. The method of claim 11 , further comprising:
generating a third pilot including information specific to said at least one user terminal and a first cover code;
generating a fourth pilot including information specific to said at least one user terminal and a second cover code, wherein the first cover code is orthogonal to the second cover code;
transmitting the third pilot from one of said plurality of antennas; and
transmitting the fourth pilot from a different one of said plurality of antennas.

14. A user terminal for use in a wireless communication system supporting multiple-input multiple output (MIMO) communications, comprising:
a receiver;
a processor operative to:
process a first pilot of a first type including information to facilitate system timing and frequency acquisition received from an access point including a plurality of antennas,
process a second pilot of a second type different from the first type including information to facilitate channel estimation between said user terminal and the access point, and
generate a channel estimate from information in said second pilot,
wherein the first pilot is neither beamformed nor spatially multiplexed and the second pilot is one of beamformed using signal processing or spatially multiplexed, and
wherein the second pilot includes a steered pilot transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

15. In a user terminal for use in a wireless communication system supporting multiple-input multiple-output (MIMO) communications, a method comprising:
receiving a first pilot of a first type including information to facilitate system timing and frequency acquisition from an access point including a plurality of antennas;
receiving a second pilot of a second type different from the first type including information to facilitate channel estimation between said user terminal and the access point; and
generating a channel estimate from information in said second pilot,
wherein the second pilot comprises a steered pilot, and wherein the steered pilot includes a pilot that was transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

16. In a user terminal for use in a wireless communication system supporting multiple-input multiple-output (MIMO) communications, a method comprising:
receiving a first pilot of a first type including information to facilitate system timing and frequency acquisition from an access point including a plurality of antennas;
receiving a second pilot of a second type different from the first type including information to facilitate channel estimation between said user terminal and the access point; and
generating a channel estimate from information in said second pilot,
wherein the information to facilitate channel estimation at least includes a steering vector and a pilot signal, and
wherein the second pilot includes a steered pilot transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

17. An access point for use in a wireless communications system supporting multiple-input multiple-output (MIMO) communications, comprising:
a plurality of antennas;
a processor operative to:
generate a plurality of pilots, said plurality of pilots including:
a first pilot of a first type including information to facilitate system timing and frequency acquisition, and
a second pilot of a second type different from the first type including information to facilitate channel estimation between said access point and at least one user terminal; and

transmit said plurality of pilots to said at least one user terminal,

wherein the first pilot is neither beamformed nor spatially multiplexed and the second pilot is one of beamformed using signal processing or spatially multiplexed, and
wherein the second pilot includes a steered pilot transmitted on specific eigenmodes of a MIMO channel for a specific user terminal.

18. A user terminal for use in a wireless communication system supporting multiple-input multiple-output (MIMO) communications, comprising:
a receiver;
a processor operative to:
receive a first pilot of a first type including information to facilitate system timing and frequency acquisition from an access point

Assignees

• Ketchum John W
• Wallace Mark S
• Walton J Rodney
• Howard Steven J
• Qualcomm Inc

Inventors

• Ketchum John W
• Wallace Mark S
• Walton J Rodney
• Howard Steven J

Classifications

• H04L1/08

  by repeating transmission, e.g. Verdan system {(H04L1/1858 and H04L1/189 take precedence)} · CPC title

• H04L5/0023

  Time-frequency-space · CPC title

• H04L1/0017

  where the mode-switching is based on Quality of Service requirement · CPC title

• H04B7/0421 Primary

  utilizing implicit feedback, e.g. steered pilot signals · CPC title

• H04L1/16

  in which the return channel carries supervisory signals, e.g. repetition request signals · CPC title