Coding and modulation for multiple data streams in a communication system

• US 8,358,714 B2
• Filed: 07/25/2005
• Issued: 01/22/2013
• Est. Priority Date: 06/16/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay Rodney, Medvedev, Irina
• Primary Examiner(s): Flores, Leon
• Application Number:
  US11/190,106
• Publication Number:
  US 20060285605A1
• Time in Patent Office: 2,738 Days
• Field of Search: 375/267, 375/299, 375/347, 375/260, 455/101, 455/132, 455/296, 455/500, 455/562.1, 370/334
• US Class Current: 375/267
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Techniques for transmitting multiple data streams to a single receiver using a single code rate and different modulation schemes are described. Channel estimates are determined for the multiple data streams and used to select a single code rate and multiple modulation schemes for the multiple data streams. The system may support a set of code rates, and each code rate may be associated with a respective set of modulation schemes that may be used with that code rate. The single code rate for all data streams is selected from among the set of supported code rates, and the modulation scheme for each data stream is selected from among the set of modulation schemes associated with the single code rate. The multiple data streams are encoded in accordance with the single code rate. Each data stream is further modulated in accordance with the modulation scheme selected for that stream.

Claims

1. An apparatus comprising:

a controller operative to obtain a selection of a single code rate and a plurality of modulation schemes for a plurality of data streams to be sent to a single receiver, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate; and

a processor operative to encode the plurality of data streams in accordance with the single code rate and to modulate the plurality of data streams in accordance with the plurality of modulation schemes said processor further operative to jointly encode the plurality of data streams in accordance with the single code rate and to independently modulate the plurality of data streams in accordance with the plurality of modulation schemes.

2. The apparatus of claim 1, wherein the plurality of data streams is constrained to one code rate selected from among a plurality of code rates, wherein each of the plurality of code rates is associated with a respective set of modulation schemes, wherein the single code rate is the one code rate selected from among the plurality of code rates.

3. The apparatus of claim 1, wherein the single code rate and the plurality of modulation schemes are for a rate combination selected from among a plurality of rate combinations.

4. The apparatus of claim 1, wherein the controller is operative to receive the selection of the single code rate and the plurality of modulation schemes from the single receiver.

5. The apparatus of claim 1, wherein the controller is operative to determine signal-to-noise-and-interference ratio (SNR) estimates for the plurality of data streams and to select the single code rate and the plurality of modulation schemes based on the SNR estimates.

6. The apparatus of claim 1, wherein the processor is operative to encode and modulate each of the plurality of data streams independently.

7. The apparatus of claim 1, further comprising:

a second processor operative to spatially process the plurality of data streams for transmission via a plurality of spatial channels in a multiple-input multiple-output (MIMO) channel.

8. A method of transmitting data in a communication system, comprising:

obtaining a selection of a single code rate and a plurality of modulation schemes for a plurality of data streams to be sent to a single receiver, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate;

encoding the plurality of data streams in accordance with the single code rate, wherein said encoding comprises jointly encoding the plurality of data streams in accordance with the single code rate; and

modulating the plurality of data streams in accordance with the plurality of modulation schemes, wherein said modulating comprises independently modulating the plurality of data streams in accordance with the plurality of modulation schemes.

9. The method of claim 8, further comprising:

spatially processing the plurality of data streams for transmission via a plurality of spatial channels in a multiple-input multiple-output (MIMO) channel.

10. An apparatus comprising:

means for obtaining a selection of a single code rate and a plurality of modulation schemes for a plurality of data streams to be sent to a single receiver, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate;

means for encoding the plurality of data streams in accordance with the single code rate, wherein said means for encoding is configured to jointly encode the plurality of data streams in accordance with the single code rate; and

means for modulating the plurality of data streams in accordance with the plurality of modulation schemes, wherein said means for modulating is configured to independently modulate the plurality of data streams in accordance with the plurality of modulation schemes.

11. The apparatus of claim 10, further comprising:

means for spatially processing the plurality of data streams for transmission via a plurality of spatial channels in a multiple-input multiple-output (MIMO) channel.

12. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single receiver; and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, said controller further operative to jointly encode the plurality of data streams in accordance with the single code rate and to independently modulate the plurality of data streams in accordance with the plurality of modulation schemes, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate.

13. The apparatus of claim 12, wherein the controller is operative to select one code rate from among a plurality of code rates and to provide the one code rate as the single code rate for the plurality of data streams.

14. The apparatus of claim 13, wherein each of the plurality of code rates is associated with a respective set of modulation schemes.

15. The apparatus of claim 12, wherein the controller is operative to select a modulation scheme for each of the plurality of data streams to achieve a non-negative SNR margin for the data stream.

16. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single reciever; and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein the channel estimates comprises a signal-to-noise-and-interference ratio (SNR) estimates and wherein the controller is operative to select the plurality of modulation schemes for the plurality of data streams such that at least one data stream has negative SNR margin and the plurality of data streams has a non-negative total SNR margin.

17. The apparatus of claim 16, wherein the controller is operative to limit the negative SNR margin for each of the at least one data stream to be within a predetermined value.

18. The apparatus of claim 17, wherein the predetermined value is determined by the single code rate selected for the plurality of data streams.

19. The apparatus of claim 17, wherein the predetermined value is determined by the single code rate selected for the plurality of data streams, an index of each of the plurality of data streams, modulation selected for each data stream, the number of data streams being transmitted, or a combination thereof.

20. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single receiver, and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein the channel estimates comprises a signal-to-noise-and-interference ratio (SNR) estimates and wherein the controller is operative to determine an overall throughput and a total SNR margin for each of a plurality of code rates, to select a code rate having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates, and to provide the selected code rate as the single code rate for the plurality of data streams.

21. The apparatus of claim 20, wherein the controller is operative to select a lowest code rate among multiple code rates having the highest overall throughput.

22. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single receiver; and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein the channel estimates comprises a signal-to-noise-and-interference ratio (SNR) estimates and wherein the processor is operative to determine received SNRs for a plurality of frequency subbands for each of the plurality of data streams and to determine an SNR estimate for each data stream based on the received SNRs for the data stream.

23. A method of performing rate selection in a communication system, comprising:

determining channel estimates for a plurality of data streams to be sent to a single receiver;

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate;

encoding the plurality of data streams in accordance with the single code rate, wherein said encoding comprises jointly encoding the plurality of data streams in accordance with the single code rate; and

modulating the plurality of data streams in accordance with the plurality of modulation schemes, wherein said modulating comprises independently modulating the plurality of data streams in accordance with the plurality of modulation schemes.

24. The method of claim 23, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the selecting the single code rate and the plurality of modulation schemes comprises:

selecting a modulation scheme for each of the plurality of data streams to achieve a non-negative SNR margin for the data stream.

25. A method of performing rate selection in a communication system, comprising:

determining channel estimates for a plurality of data streams to be sent to a single receiver;

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates;

encoding the plurality of data streams in accordance with the single code rate; and

modulating the plurality of data streams in accordance with the plurality of modulation schemes,

wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the selecting the single code rate and the plurality of modulation schemes comprises;

selecting the plurality of modulation schemes for the plurality of data streams such that at least one data stream has negative SNR margin and the plurality of data streams have a non-negative total SNR margin.

26. A method of performing rate selection in a communication system, comprising:

determining channel estimates for a plurality of data streams to be sent to a single receiver;

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates;

encoding the plurality of data streams in accordance with the single code rate; and

modulating the plurality of data streams in accordance with the plurality of modulation schemes,

wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the selecting the single code rate and the plurality of modulation schemes comprises;

determining an overall throughput and a total SNR margin for each of a plurality of code rates, and

selecting a code rate having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates, wherein the single code rate is the selected code rate.

27. An apparatus comprising:

means for determining channel estimates for a plurality of data streams to be sent to a single receiver; and

means for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, said means for selecting a single code rate operative to jointly encode the plurality of data streams in accordance with the single code rate and to independently modulate the plurality of data streams in accordance with the plurality of modulation schemes, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate.

28. The apparatus of claim 27, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the means for selecting the single code rate and the plurality of modulation schemes comprises:

means for selecting a modulation scheme for each of the plurality of data streams to achieve a non-negative SNR margin for the data stream.

29. An apparatus comprising:

means for determing channel estimates for a plurality of data streams to be sent to a single receiver; and

means for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates,

wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the means for selecting the single code rate and the plurality of modulation schemes comprises;

means for selecting the plurality of modulation schemes for the plurality of data streams such that at least one data stream has negative SNR margin and the plurality of data streams have a non-negative total SNR margin.

30. An apparatus comprising:

means for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates,

wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates and wherein the means for selecting the single code rate and the plurality of modulation schemes comprises;

means for determining an overall throughput and a total SNR margin for each of a plurality of code rates, and

means for selecting a code rate having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates, wherein the single code rate is the selected code rate.

31. A processor readable non-transitory media encoded with a computer program, the computer program comprising instructions for:

determining channel estimates for a plurality of data streams to be sent to a single receiver;

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein a modulation scheme for each of the plurality of data streams is selected from among a set of modulation schemes associated with the single code rate;

encoding, jointly, the plurality of data streams in accordance with the single code rate; and

modulating, independently, the plurality of data streams in accordance with the plurality of modulation schemes.

32. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprises a signal-to-noise-and-interference ratio (SNR) estimates; and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein the controller is operative to determine an overall throughput and a total SNR margin for each of a plurality of code rates for each of a plurality of stream combinations, to select a code rate and a stream combination having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates and the plurality of stream combinations, and to provide the selected code rate as the single code rate, wherein each stream combination corresponds to a different number of data streams, and wherein the plurality of data streams are for the selected stream combination.

33. The apparatus of claim 32, wherein the controller is operative to select a stream combination with fewest data streams among multiple stream combinations having the highest overall throughput.

34. An apparatus comprising:

a processor operative to determine channel estimates for a plurality of data streams to be sent to a single receiver wherein the channel estimates comprises a signal-to-noise-and-interference ratio (SNR) estimates; and

a controller operative to select a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, wherein the controller is operative to determine a total SNR margin for each of a plurality of rate combinations, to select a rate combination having a highest overall throughput and a non-negative total SNR margin among the plurality of rate combinations, and to obtain the single code rate and the plurality of modulation schemes from the selected rate combination, wherein each rate combination is associated with a specific number of data streams, a specific code rate for all of the data streams, a specific modulation scheme for each of the data streams, and a specific overall throughput for all of the data streams.

35. The apparatus of claim 34, wherein the controller is operative to select a rate combination with fewest data streams among multiple rate combinations having the highest overall throughput.

36. The apparatus of claim 34, wherein the controller is operative to select a rate combination with a largest total SNR margin among multiple rate combinations having the highest overall throughput.

37. The apparatus of claim 34, further comprising:

a memory configured to store a look-up table of the plurality of rate combinations arranged in an order determined by a required SNR for one data stream in each of the plurality of rate combinations, and wherein the controller is operative to select the rate combination based on the look-up table.

38. A method of performing rate selection in a communication system, comprising:

determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates by;

determining an overall throughput and a total SNR margin for each of a plurality of code rates for each of a plurality of stream combinations, wherein each stream combination corresponds to a different number of data streams,

selecting a code rate and a stream combination having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates and the plurality of stream combinations, wherein the single code rate is the selected code rate and the plurality of data streams are for the selected stream combination;

encoding data streams of the selected stream combination in accordance with the selected code rate; and

modulating the data streams of the selected stream combination in accordance with the selected plurality of modulation schemes.

39. A method of performing rate selection in a communication system, comprising:

determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates by;

determining a total SNR margin for each of a plurality of rate combinations, wherein each rate combination is associated with a specific number of data streams to transmit, a specific code rate for all of the data streams, a specific modulation scheme for each of the data streams, and a specific overall throughput for all of the data streams, and

selecting a rate combination having a highest overall throughput and a non-negative total SNR margin among the plurality of rate combinations, wherein the single code rate and the plurality of modulation schemes are for the selected rate combination.

40. An apparatus comprising:

means for determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

means for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates comprising

means for determining an overall throughput and a total SNR margin for each of a plurality of code rates for each of a plurality of stream combinations, wherein each stream combination corresponds to a different number of data streams, and

means for selecting a code rate and a stream combination having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates and the plurality of stream combinations, wherein the single code rate is the selected code rate and the plurality of data streams are for the selected stream combination.

41. An apparatus comprising:

means for determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

means for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates, comprising

means for determining a total SNR margin for each of a plurality of rate combinations, wherein each rate combination is associated with a specific number of data streams, a specific code rate for all of the data streams, a specific modulation scheme for each of the data streams, and a specific overall throughput for all of the data streams, and

means for selecting a rate combination having a highest overall throughput and a non-negative total SNR margin among the plurality of rate combinations, wherein the single code rate and the plurality of modulation schemes are for the selected rate combination.

42. A computer-program product for performing rate selection in a communication system comprising a computer readable non-transitory medium having instructions stored thereon, the instructions being executable by one or more processors and the computer program comprising instructions for:

instructions for determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

instructions for selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates by;

determining an overall throughput and a total SNR margin for each of a plurality of code rates for each of a plurality of stream combinations, wherein each stream combination corresponds to a different number of data streams, and

selecting a code rate and a stream combination having a highest overall throughput and a non-negative total SNR margin among the plurality of code rates and the plurality of stream combinations, wherein the single code rate is the selected code rate and the plurality of data streams are for the selected stream combination.

43. A computer-program product for performing rate selection in a communication system comprising a computer readable non-transitory medium having instructions stored thereon, the instructions being executable by one or more processors and the computer program comprising instructions for:

determining channel estimates for a plurality of data streams to be sent to a single receiver, wherein the channel estimates comprise signal-to-noise-and-interference ratio (SNR) estimates; and

selecting a single code rate and a plurality of modulation schemes for the plurality of data streams based on the channel estimates by;

determining a total SNR margin for each of a plurality of rate combinations, wherein each rate combination is associated with a specific number of data streams to transmit, a specific code rate for all of the data streams, a specific modulation scheme for each of the data streams, and a specific overall throughput for all of the data streams, and

selecting a rate combination having a highest overall throughput and a non-negative total SNR margin among the plurality of rate combinations, wherein the single code rate and the plurality of modulation schemes are for the selected rate combination.