Codeword permutation and reduced feedback for grouped antennas

• US 8,798,201 B2
• Filed: 09/05/2007
• Issued: 08/05/2014
• Est. Priority Date: 09/06/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kim, Byoung-Hoon
• Primary Examiner(s): NEFF, MICHAEL R
• Application Number:
  US11/850,451
• Publication Number:
  US 20080080641A1
• Time in Patent Office: 2,526 Days
• Field of Search: 375/299
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0641 Differential feedback
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

Systems and methodologies are described that facilitate reducing feedback required to be transmitted on a reverse link channel in response to a forward link data transmission for multiple-input multiple-output (MIMO) wireless communication systems. In a per group rate control MIMO system, a codeword can be linked to more than one layer. Codewords are mixed among antennas in the MIMO systems based upon a symmetric permutation of antennas groups. Further, codewords are transmitted in permuted form so that receivers can reduce feedback to a base channel quality indicator (CQI) and a differential CQI. Additionally, spatial diversity is increased for each codeword improving the robustness of the system against inaccurate CQI reports.

Claims

1. A method that facilitates reducing required feedback for data rate control in wireless communication, comprising:

determining one or more groupings of a plurality of transmit antennas;

permuting data stream codewords according to a permutation of the one or more groupings of the transmit antennas;

transmitting the permuted codewords through the one or more groupings of the transmit antennas over a forward link channel; and

receiving a condensed channel quality indicator (CQI) as feedback related to transmitting the permuted codewords, wherein the condensed CQI comprises a base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword,

wherein determining the one or more groupings comprises identifying active antennas among the plurality of transmit antennas and disregarding inactive antennas when formulating the one or more groupings.

2. The method of claim 1, further comprising:

determining a layer to codeword ratio; and

restricting a size of the one or more groupings to the layer to codeword ratio.

3. The method of claim 2, wherein each codeword corresponds to one layer.

4. The method of claim 2, wherein each codeword corresponds to two layers.

5. The method of claim 1, further comprising:

adjusting at least one of a data rate, code rate, or modulation scheme of subsequent codewords transmitted based upon the condensed CQI.

6. The method of claim 5, wherein the condensed CQI comprises the base CQI reflecting the signal quality metric of the first decoded codeword and a differential CQI reflecting a signal quality gain obtained by cancelling the first decoded codeword in decoding a second codeword.

7. The method of claim 6, wherein the signal quality metric is one of a signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ratio (SINR).

8. The method of claim 6, wherein adjusting subsequent codewords comprises:

adjusting the at least one of a data rate, code rate, or modulation scheme of a subsequent codeword according to the base CQI; and

adjusting the at least one of a data rate, code rate, or modulation scheme of additional subsequent codewords based upon a sum of the base CQI and a multiple of the differential CQI.

9. The method of claim 1, wherein the plurality of transmit antennas include one or more physical or virtual antennas.

10. The method of claim 1, wherein adjusting subsequent codewords comprises:

adjusting the at least one of a data rate, code rate, or modulation scheme of subsequent codewords based upon the base CQI.

11. The method of claim 1, wherein permuting codewords comprises distributing codeword blocks amongst all antenna groups such that each codeword is transmitted in part over each antenna in the plurality of antennas.

12. A wireless communications apparatus employable in a multiple-input, multiple-output system, comprising:

means for identifying a level of codeword to layer correspondence;

means for formulating groups of transmit antennas based at least in part on the level of codeword to layer correspondence, wherein the means for formulating groups comprises means for identifying active antennas and means for disregarding inactive antennas;

means for performing symmetrical permutations of at least two codewords;

means for transmitting the at least two permuted codewords through the formulated antenna groups; and

means for utilizing feedback related to the transmission of the at least two permuted codewords, wherein the feedback comprises a condensed channel quality indicator (CQI) that comprises base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword,

wherein the condensed CQI comprises the base CQI reflecting the signal quality metric of the first decoded codeword and a differential CQI reflecting a signal quality gain obtained by cancelling the first decoded codeword in decoding a second codeword.

13. A wireless communications apparatus, comprising:

a memory that retains instructions related to grouping transmit antennas, permuting codeword symbols based upon the antenna groupings, and utilizing feedback to adjust transmission performance, wherein the feedback comprises a condensed channel quality indicator (CQI) related to transmitting the permuted codeword symbols that comprises a base CQI reflecting a signal quality metric of both a first decoded codeword symbol and a second decoded codeword symbol; and

a processor, coupled to the memory, configured to execute the instructions retained in the memory,

wherein the memory further retains instructions related to determining a number of active antennas and identifying a level of codeword to layer correspondence.

14. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:

grouping transmit antennas based upon a correspondence between codewords and layers;

shuffling codeword blocks across antenna groupings based upon symmetrical permutations of the groupings;

transmitting the shuffled codeword blocks via a forward link channel through the transmit antennas;

receiving a condensed feedback metric relating to the transmission of the shuffled codeword blocks, wherein the condensed feedback metric comprises a condensed channel quality indicator (CQI) that comprises a base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword; and

adjusting subsequent transmissions based at least in part on the received feedback,

wherein grouping the transmit antennas comprises identifying active antennas and disregarding inactive antennas.

15. The machine-readable medium of claim 14, wherein the correspondence specifies for each transmission rank a number of layers associated with each codeword.

16. The machine-readable medium of claim 15, wherein at least one layer is associated with a codeword.

17. The machine-readable medium of claim 15, wherein at least two layers are associated with a codeword.

18. The machine-readable medium of claim 14, wherein the condensed feedback metric comprises the base CQI reflecting the signal quality metric of the first decoded codeword and a differential CQI reflecting a signal quality gain obtained by cancelling interference of the first decoded codeword in decoding a second codeword.

19. The machine-readable medium of claim 18, wherein adjusting subsequent transmissions comprises:

altering at least one of a data rate, code rate or modulation scheme of a subsequent codeword in response to the base CQI; and

altering at least one of a data rate, code rate or modulation scheme of additional subsequent codewords based upon a sum of the base CQI and a multiple of the differential CQI.

20. The machine-readable medium of claim 18, wherein adjusting subsequent transmission comprises adjusting the at least one of a data rate, code rate or modulation scheme of a subsequent codeword and additional subsequent codewords based upon the base CQI.

21. The machine-readable medium of claim 18, wherein the signal quality metric is one of a signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ratio (SINR).

22. The machine-readable medium of claim 14, wherein a size of an antenna group is determined from the correspondence between codewords and layers.

23. The machine-readable medium of claim 14, wherein the transmit antennas include one or more physical or virtual antennas.

24. A method that generates reduced feedback in a wireless communication system, comprising:

unmixing permuted codeword blocks according to a permutation scheme employed during transmission;

evaluating a condensed channel quality indicator (CQI) related to the permuted codeword blocks, wherein the condensed CQI comprises a base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword;

regenerating interference created by the first codeword during transmission; and

evaluating a differential CQI related to quality increase resulting from cancelling the regenerated interference in decoding the second codeword.

25. The method of claim 24, further comprising decoding the unmixed codeword blocks.

26. The method of claim 24, wherein the condensed CQI further comprises a differential CQI, and wherein the base CQI and the differential CQI are based at least upon a signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ratio (SINR).

27. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:

grouping transmit antennas based upon a correspondence between codewords and layers;

shuffling codeword blocks across antenna groupings based upon symmetrical permutations of the groupings;

transmitting the shuffled codeword blocks via a forward link channel through the transmit antennas;

receiving a condensed feedback metric relating to the transmission of the shuffled codeword blocks, wherein the condensed feedback metric comprises a condensed channel quality indicator (CQI) that comprises a base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword; and

adjusting subsequent transmissions based at least in part on the received condensed feedback metric,

wherein shuffling codeword blocks comprises symmetrically permuting codewords over all groupings such that each codeword transmits in part over all antennas.