Method and apparatus for performing sequential closed loop multiple input multiple output (MIMO)

• US 7,609,780 B2
• Filed: 09/30/2004
• Issued: 10/27/2009
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Sadowsky, John S.
• Primary Examiner(s): Torres; Juan A
• Application Number:
  US10/954,582
• Publication Number:
  US 20060071807A1
• Time in Patent Office: 1,853 Days
• Field of Search: 375/267, 375/299, 375/297, 455/101
• US Class Current: 375/297
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0636 Feedback format

Abstract

In a communication system using closed loop multiple input/multiple output MIMO, beam forming information may be fed back from a receiver to a transmitter sequentially over a number of frames. The beam forming matrices that are fed back may be quantized.

Claims

1. A wireless device comprising:

a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame;

a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame;

a second storage area to store a feedback matrix received from a remote device; and

a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix.

2. The wireless device of claim 1, wherein:

said feedback matrix received from said remote device is quantized.

3. The wireless device of claim 1, wherein:

said wireless device is for use in a wireless network where data is transmitted in wireless frame exchange sequences, wherein said feedback matrix is received from said remote device as part of a response frame that also includes an acknowledgement packet.

4. The wireless device of claim 3, wherein:

said combiner generates updated beam forming matrices for multiple successive data frames transmitted during a frame exchange sequence.

5. A wireless device comprising:

at least one dipole antenna;

a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame, said multiple antennas including said at least one dipole antenna;

a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame;

a second storage area to store a feedback matrix received from a remote device; and

a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix.

6. The wireless device of claim 5, wherein:

said combiner is a multiplication unit.

7. The wireless device of claim 5, wherein:

said feedback matrix received from said remote device is quantized.

8. An article comprising a computer readable storage medium having instructions stored thereon that, when executed by a computing platform, operate to:

receive a signal Y_i from a MIMO channel, said signal Y_i including data symbols X_i that were matrix multiplied by a beam forming matrix V_i within a remote transmitter before being transmitted into said MIMO channel, said MIMO channel having a channel matrix H_i;

use said signal Y_i to determine a combined channel {tilde over (H)}_i that includes effects of both the beam forming matrix V_i and the channel matrix H_i;

perform a singular value decomposition (SVD) of the combined channel {tilde over (H)}_i to determine a beam forming matrix {tilde over (V)}_i representing a correction that is needed for the beam forming matrix V_i; and

transmit said beam forming matrix {tilde over (V)}_i to said remote transmitter to be multiplied with said beam forming matrix V_i to generate a new beam forming matrix V_i+1 for use in a subsequent data transmission from said remote transmitter.

9. The article of claim 8, wherein said instructions further operate to:

quantize said beam forming matrix {tilde over (V)}_i before it is transmitted.

10. The article of claim 8, wherein said instructions further operate to:

quantize said beam forming matrix {tilde over (V)}_i using vector quantization techniques before said beam forming matrix {tilde over (V)}_i is transmitted.

11. The article of claim 8, wherein said instructions further operate to:

quantize said beam forming matrix {tilde over (V)}_i using adaptive quantization techniques before said beam forming matrix {tilde over (V)}_i is transmitted.

12. A wireless device comprising:

a plurality of antennas; and

a digital processing device to support communication with a remote wireless device via a multiple input/multiple output (MIMO) channel, said digital processing device being programmed to;

receive a signal Y_i from said MIMO channel, said signal Y_i including data symbols X_i that were matrix multiplied by a beam forming matrix V_i within a transmitter of said remote wireless device before being transmitted into said MIMO channel, said MIMO channel having a channel matrix H_i;

use said signal Y_i to determine a combined channel {tilde over (H)}_i that includes effects of both the beam forming matrix V_i and the channel matrix H_i;

perform singular value decomposition (SVD) of the combined channel {tilde over (H)}_i to determine a beam forming matrix {tilde over (V)}_i representing a correction that is needed for the beam forming matrix V_i; and

transmit said beam forming matrix {tilde over (V)}_i to said remote wireless device to be multiplied with said beam forming matrix V_i to generate a new beam forming matrix V_i+1 for use in a subsequent data transmission from said remote wireless device.

13. The wireless device of claim 12, wherein:

said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and

receive, use, perform, and transmit are repeated for multiple successive data frames received during said frame exchange sequence.

14. The wireless device of claim 12, wherein:

said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and

transmission of said beam forming matrix {tilde over (V)}_i to said remote wireless device includes transmitting said beam forming matrix {tilde over (V)}_i as part of a response frame that also includes an acknowledgement packet.

15. The wireless device of claim 12, wherein said digital processing device is programmed to:

quantize said beam forming matrix {tilde over (V)}_i before transmitting it to said remote wireless device.

16. The wireless device of claim 12, wherein said digital processing device is programmed to:

quantize said beam forming matrix {tilde over (V)}_i using vector quantization techniques before transmitting it to said remote wireless device.

17. The wireless device of claim 12, wherein said digital processing device is programmed to:

quantize said beam forming matrix {tilde over (V)}_i using Grassmanian beam forming techniques before transmitting it to said remote wireless device.

18. The wireless device of claim 12, wherein said digital processing device is programmed to:

quantize said beam forming matrix {tilde over (V)}_i using adaptive quantization techniques before transmitting it to said remote wireless device.

19. The wireless device of claim 12, wherein said digital processing device is programmed to:

quantize said beam forming matrix {tilde over (V)}_i using differential quantization techniques before transmitting it to said remote wireless device.