CQI AND RANK PREDICTION FOR LIST SPHERE DECODING AND ML MIMO RECEIVERS

• US 20120044982A1
• Filed: 11/02/2011
• Published: 02/23/2012
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sampath, Hemanth, Kadous, Tamer
• Granted Patent: US 8,767,885 B2
• Time in Patent Office: Days
• US Class Current: 375/228
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 1/0675 characterised by the signaling
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/03242 Methods involving sphere decoding

Abstract

Systems and methodologies are described that facilitate integrating a list-sphere decoding design in a multiple input-multiple output (MIMO wireless communication environment. According to various aspects, optimal rank selection and CQI computation for an optimal rank can be performed in conjunction with a non-linear receiver, such as a maximum life (ML) MMSE receiver, a non-linear receiver with a list-sphere decoder, and the like. Optimal rank selection can be performed using a maximum rank selection protocol, a channel capacity-based protocol, or any other suitable protocol that facilitates rank selection, and CQI information can be generated based in part on effective SNRs determined with regard to a selected optimal rank.

Claims

1. A method of determining an indication of channel quality in a non-linear receiver, the method comprising:

calculating spectral efficiency assuming a maximum possible rank for the non-linear receiver for different code rates and different quadrature amplitude modulation schemes;

selecting a desired spectral efficiency of the calculated spectral efficiencies; and

calculating the indication of channel quality as a function of an effective signal-to-noise ratio for at least the desired spectral efficiency.

2. The method of claim 1 further comprising averaging each of the spectral efficiencies across a plurality of tones and symbols in a frame.

3. The method of claim 1 further comprising quantizing the indication of channel quality and feeding back the quantized indication of channel quality over a reverse link.

4. A user device in a wireless communication environment, the user device comprising:

a non-linear receiver configured to receive a transmission signal;

a processor communicatively coupled to the receiver and configured to;

calculate spectral efficiency assuming a maximum possible rank for the non-linear receiver for different code rates and different quadrature amplitude modulation schemes;

select a desired spectral efficiency of the calculated spectral efficiencies; and

calculate an indication of channel quality as a function of an effective signal-to-noise ratio for at least the desired spectral efficiency.

5. The device of claim 4 wherein the processor is further configured to average each of the spectral efficiencies across a plurality of tones and symbols in a frame.

6. The device of claim 4 wherein the processor is further configured to quantize the indication of channel quality and feed back the quantized indication of channel quality over a reverse link.

7. A user device in a wireless communication environment, the user device comprising:

means for calculating spectral efficiency assuming a maximum possible rank for a non-linear receiver for different code rates and different quadrature amplitude modulation schemes;

means for selecting a desired spectral efficiency of the calculated spectral efficiencies; and

means for calculating an indication of channel quality as a function of an effective signal-to-noise ratio for at least the desired spectral efficiency.

8. The device of claim 7 further comprising means for averaging each of the spectral efficiencies across a plurality of tones and symbols in a frame.

9. The device of claim 7 further comprising means for quantizing the indication of channel quality and means for feeding back the quantized indication of channel quality over a reverse link.

10. A computer program product residing on a tangible processor-readable medium and comprising processor-readable instructions configured to cause a processor to:

calculate spectral efficiency assuming a maximum possible rank for a non-linear receiver for different code rates and different quadrature amplitude modulation schemes;

select a desired spectral efficiency of the calculated spectral efficiencies; and

calculate an indication of channel quality as a function of an effective signal-to-noise ratio for at least the desired spectral efficiency.

11. The computer program product of claim 10 further comprising instructions configured to cause the processor to average each of the spectral efficiencies across a plurality of tones and symbols in a frame.

12. The computer program product of claim 10 further comprising instructions configured to cause the processor to quantize the indication of channel quality and feed back the quantized indication of channel quality over a reverse link.

13. A method of determining rank of a non-linear receiver, the method comprising:

receiving a transmission signal at a minimum mean-square error non-linear receiver;

determining successive interference cancellation capacity for each of a plurality of ranks of the non-linear receiver; and

selecting a desired rank, of the plurality of ranks, whose corresponding capacity is higher than the capacity corresponding to each other rank of the plurality of ranks.

14. The method of claim 13 further comprising generating channel sub-matrices and evaluating the channel sub-matrices for each of the plurality of ranks.

15. A user device in a wireless communication environment, the user device comprising:

a non-linear receiver configured to receive a transmission signal;

a processor communicatively coupled to the receiver and configured to;

determine successive interference cancellation capacity for each of a plurality of ranks of the non-linear receiver; and

select a desired rank, of the plurality of ranks, whose corresponding capacity is higher than the capacity corresponding to each other rank of the plurality of ranks.

16. The device of claim 15 wherein the processor is further configured to generate channel sub-matrices and evaluate the channel sub-matrices for each of the plurality of ranks.

17. A user device in a wireless communication environment, the user device comprising:

means for receiving a transmission signal at a minimum mean-square error non-linear receiver;

means for determining successive interference cancellation capacity for each of a plurality of ranks of the non-linear receiver; and

means for selecting a desired rank, of the plurality of ranks, whose corresponding capacity is higher than the capacity corresponding to each other rank of the plurality of ranks.

18. The method of claim 17 further comprising generating channel sub-matrices and evaluating the channel sub-matrices for each of the plurality of ranks.

19. A computer program product residing on a tangible processor-readable medium and comprising processor-readable instructions configured to cause a processor to:

determine successive interference cancellation capacity for each of a plurality of ranks of a non-linear receiver; and

select a desired rank, of the plurality of ranks, whose corresponding capacity is higher than the capacity corresponding to each other rank of the plurality of ranks.

20. The computer program product of claim 19 further comprising instructions configured to cause the processor to generate channel sub-matrices and evaluate the channel sub-matrices for each of the plurality of ranks.