CQI and rank prediction for list sphere decoding and ML MIMO receivers

• US 8,767,885 B2
• Filed: 11/02/2011
• Issued: 07/01/2014
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sampath, Hemanth, Kadous, Tamer
• Primary Examiner(s): Vlahos, Sophia
• Application Number:
  US13/287,912
• Publication Number:
  US 20120044982A1
• Time in Patent Office: 972 Days
• Field of Search: 375/221, 375/224, 375/227, 375/228, 375/260, 375/267, 375/346, 375/340, 370/252, 370/335, 370/338, 370/242, 370/465, 370/468
• US Class Current: 375/340
• 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, by a processing device, spectral efficiencies, with a maximum possible rank selected for the non-linear receiver, for varied code rates and quadrature amplitude modulation schemes to achieve a desired spectral efficiency; and

calculating, by the processing device, the indication of channel quality as a function of an effective signal-to-noise ratio calculated from 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 efficiencies, with a maximum possible rank selected for the non-linear receiver, for varied code rates and quadrature amplitude modulation schemes to achieve a desired spectral efficiency; and

calculate an indication of channel quality as a function of an effective signal-to-noise ratio calculated from 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 efficiencies, with a maximum possible rank selected for a non-linear receiver, for varied code rates and quadrature amplitude modulation schemes to achieve a desired spectral efficiency; and

means for calculating an indication of channel quality as a function of an effective signal-to-noise ratio calculated from 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 non-transitory processor-readable medium and comprising processor-readable instructions configured to cause a processor to:

calculate spectral efficiencies, with a maximum possible rank selected for a non-linear receiver, for varied code rates and quadrature amplitude modulation schemes to achieve a desired spectral efficiency; and

calculate an indication of channel quality as a function of an effective signal-to-noise ratio calculated from 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 (SIC) capacity for each of a plurality of possible ranks for the non-linear receiver achieved by employing a successive interference cancellation procedure at the non-linear receiver; and

selecting, according to the SIC capacity determined for each of the plurality of possible ranks for the non-linear receiver, a rank, from the plurality of possible ranks for the non-linear receiver, whose corresponding determined SIC capacity is higher than determined SIC capacities of other of the plurality of possible 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 (SIC) capacity for each of a plurality of possible ranks for the non-linear receiver achieved by employing a successive interference cancellation procedure at the non-linear receiver; and

select, according to the SIC capacity determined for each of the plurality of possible ranks for the non-linear receiver, a rank, from the plurality of possible ranks for the non-linear receiver, whose corresponding determined SIC capacity is higher than determined SIC capacities of other of the plurality of possible 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 (SIC) capacity for each of a plurality of possible ranks for the non-linear receiver achieved by employing a successive interference cancellation procedure at the non-linear receiver; and

means for selecting, according to the SIC capacity determined for each of the plurality of possible ranks for the non-linear receiver, a rank, from the plurality of possible ranks for the non-linear receiver, whose corresponding determined SIC capacity is higher than determined SIC capacities of other of the plurality of possible 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 non-transitory processor-readable medium and comprising processor-readable instructions configured to cause a processor to:

determine successive interference cancellation (SIC) capacity for each of a plurality of possible ranks for a non-linear receiver achieved by employing a successive interference cancellation procedure at the non-linear receiver; and

select, according to the SIC capacity determined for each of the plurality of possible ranks for the non-linear receiver, a rank, from the plurality of possible ranks for the non-linear receiver, whose corresponding determined SIC capacity is higher than determined SIC capacities of other of the plurality of possible 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.