Unified closed loop SU/MU-MIMO signaling and codebook design

• US 20090086842A1
• Filed: 09/28/2007
• Published: 04/02/2009
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Lin, Xintian E., Li, Qinghua, Shi, Jun
• Granted Patent: US 8,254,486 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 1/0693 Partial feedback, e.g. partial channel state information [CSI]
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

A multi-resolution codebook is used to provide quantization for channel related information in a wireless network that supports both single-user MIMO and multi-user MIMO. The multi-resolution codebook may include a higher resolution “fine” codebook for use with MU-MIMO subscriber stations and a lower resolution “coarse” codebook for use with SU-MIMO subscriber stations. A tracking codebook may also be used to provide quantization for updates to channel related information. In at least one embodiment, the tracking codebook includes a number of unit vectors (or orthogonal matrices) disposed upon a sphere cap.

Claims

1. A method comprising:

receiving first channel feedback at a base station from a first wireless device implementing multi-user multiple input, multiple output (MU-MIMO), said first channel feedback describing a downlink channel from said base station to said first wireless device, wherein said first channel feedback is quantized using a first codebook;

pre-coding first data for transmission to said first wireless device, using said first channel feedback;

receiving second channel feedback at said base station from a second wireless device implementing single-user MIMO (SU-MIMO), said second channel feedback describing a downlink channel from said base station to said second wireless device, wherein said second channel feedback is quantized using a second codebook that is smaller than, and a subset of, said first codebook; and

pre-coding second data for transmission to said second wireless device, using said second channel feedback.

2. The method of claim 1, wherein:

said first channel feedback includes an index of a code word from said first codebook that most nearly resembles a beam forming vector or matrix generated within said first wireless device; and

said second channel feedback includes an index of a code word within said second codebook that most nearly resembles a beam forming vector or matrix generated within said second wireless device.

3. The method of claim 1, further comprising:

receiving third channel feedback at said base station from said first wireless device implementing MU-MIMO, said third channel feedback describing a difference between a previously received beam forming vector or matrix of said first wireless device and a more recent beam forming vector or matrix, wherein said third channel feedback is quantized using a third codebook that includes a number of unit vectors or orthogonal matrixes on a cap of a sphere.

4. The method of claim 3, further comprising:

updating a beam forming vector or matrix associated with said first wireless device using said third channel feedback to generate an updated beam forming vector or matrix; and

pre-coding third data for transmission to said first wireless device using said updated beam forming vector.

5. The method of claim 3, wherein:

said cap of said sphere of said third codebook is centered about said previously received beam forming vector or matrix.

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

obtain first channel feedback from a first wireless device implementing multi-user multiple input, multiple output (MU-MIMO), said first channel feedback describing a downlink channel from a base station to said first wireless device, wherein said first channel feedback is quantized using a first codebook;

pre-code first data for transmission to said first wireless device using said first channel feedback;

obtain second channel feedback from a second wireless device implementing single-user MIMO (SU-MIMO), said second channel feedback describing a downlink channel from said base station to said second wireless device, wherein said second channel feedback is quantized using a second codebook that is smaller than, and a subset of, said first codebook; and

pre-code second data for transmission to said second wireless device using said second channel feedback.

7. The article of claim 6, wherein:

said first channel feedback includes an index of a code word from said first codebook that most nearly resembles a beam forming vector or matrix generated within said first wireless device; and

said second channel feedback includes an index of a code word within said second codebook that most nearly resembles a beam forming vector or matrix generated within said second wireless device.

8. The article of claim 6, wherein said instructions further operate to:

obtain third channel feedback from said first wireless device implementing MU-MIMO, said third channel feedback describing a difference between a previously received beam forming vector or matrix of said first wireless device and a more recent beam forming vector or matrix of said first wireless device, wherein said third channel feedback is quantized using a third codebook that includes a number of unit vectors or orthogonal matrices on a cap of a sphere.

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

update a beam forming vector or matrix associated with said first wireless device using said third channel feedback to generate an updated beam forming vector or matrix; and

pre-code third data for transmission to said first wireless device using said updated beam forming vector or matrix.

10. The article of claim 8, wherein:

said cap of said sphere associated with said third codebook is centered about said previously received beam forming vector or matrix of said first wireless device.

11. An apparatus comprising:

a wireless transceiver to receive signals from a MIMO channel and to transmit signals into said MIMO channel; and

a controller to;

obtain, via said wireless transceiver, first channel feedback from a first wireless device implementing multi-user multiple input, multiple output (MU-MIMO), said first channel feedback describing a downlink channel from a base station to said first wireless device, wherein said first channel feedback is quantized using a first codebook;

pre-code first data for transmission to said first wireless device via said wireless transceiver, using said first channel feedback;

obtain, via said wireless transceiver, second channel feedback from a second wireless device implementing single-user MIMO (SU-MIMO), said second channel feedback describing a downlink channel from said base station to said second wireless device, wherein said second channel feedback is quantized using a second codebook that is smaller than, and a subset of, said first codebook; and

pre-code second data for transmission to said second wireless device via said wireless transceiver, using said second channel feedback.

12. The apparatus of claim 11, wherein:

said first channel feedback includes an index of a code word from said first codebook that most nearly resembles a beam forming vector or matrix generated within said first wireless device; and

said second channel feedback includes an index of a code word within said second codebook that most nearly resembles a beam forming vector or matrix generated within said second wireless device.

13. The apparatus of claim 11, wherein said controller is to:

obtain third channel feedback from said first wireless device implementing MU-MIMO, said third channel feedback describing a difference between a previously received beam forming vector or matrix of said first wireless device and a more recent beam forming vector or matrix of said first wireless device, wherein said third channel feedback is quantized using a third codebook that includes a number of unit vectors or orthogonal matrices on a cap of a sphere.

14. The apparatus of claim 13, wherein said controller is to:

update a beam forming vector or matrix associated with said first wireless device using said third channel feedback to generate an updated beam forming vector or matrix; and

pre-code third data for transmission to said first wireless device using said updated beam forming vector or matrix.

15. The apparatus of claim 13, wherein:

said cap of said sphere associated with said third codebook is centered about said previously received beam forming vector or matrix of said first wireless device.

16. A method comprising:

generating a fine codebook for use in quantizing channel related information for multiple-user MIMO user devices in a wireless network, said fine codebook having N code words; and

generating a coarse codebook for use in quantizing channel related information for single-user MIMO user devices in the wireless network, said coarse codebook having M code words, where M<

N, wherein said coarse codebook is a subset of said fine codebook.

17. The method of claim 16, wherein:

generating a fine codebook includes generating said fine codebook using an LBG algorithm; and

generating a coarse codebook includes performing a greedy search on said fine codebook.

18. The method of claim 16, wherein:

generating a coarse codebook includes assembling a number of candidate coarse codebooks using code words from said fine codebook;

calculating a metric for each of said candidate coarse codebooks; and

selecting one of said candidate coarse codebooks based on said calculated metrics.

19. The method of claim 16, wherein:

generating a coarse codebook includes generating said coarse codebook using an LBG algorithm; and

generating a fine codebook includes;

generating N−

M random vectors; and

using said N−

M random vectors and said M code words of said coarse codebook as initial code words in said LBG algorithm.

20. The method of claim 16, wherein:

said channel related information includes beam forming vectors or matrices.