Method and apparatus for processing data for transmission in a multi-channel communication system using selective channel inversion

• US 20060291582A1
• Filed: 06/30/2006
• Published: 12/28/2006
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ketchum, John W., Walton, Jay R.
• Granted Patent: US 7,649,954 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0439 utilizing channel inversion
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0647 Variable feedback rate
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• 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 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0019 in which mode-switching is based on a statistical approach
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2001/0096 Channel splitting in point-to-point links
• CPC Class Codes: H04L 2025/03414 Multicarrier
• 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 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0244 with inversion
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03159 : operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 25/03343 : Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0023 : Time-frequency-space
• CPC Class Codes: H04L 5/0037 : Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0044 : allocation of payload
• CPC Class Codes: H04L 5/0046 : Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/006 : Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0091 : Signaling for the administration of the divided path
• CPC Class Codes: H04L 5/023 : Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/06 : the signals being represented by different frequencies combined with time-division multiplexing H04L5/26
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/346 : distributing total power among users or channels
• CPC Class Codes: H04W 52/42 : in systems with time, space, frequency or polarisation diversity

Abstract

Techniques to process data for transmission over multiple transmission channels. The available transmission channels are segregated into one or more groups, and the channels in each group are selected for use for data transmission. Data for each group is coded and modulated based on a particular coding and modulation scheme to provide modulation symbols, and the modulation symbols for each selected channel are weighted based on an assigned weight. The weighting “inverts” the selected channels such that they achieve similar received SNRs. With selective channel inversion, only “good” channels in each group having SNRs at or above a particular threshold are selected, “bad” channels are not used, and the total available transmit power for the group is distributed across the good channels in the group. Improved performance is achieved by using only good channels in each group and matching each selected channel'"'"'s received SNR to the required SNR.

Claims

1. A method for processing data for transmission over multiple transmission channels in a multi-channel communication system, comprising:

determining characteristics of a plurality of transmission channels available for data transmission;

segregating the plurality of transmission channels into one or more groups of transmission channels; and

for each group of transmission channels,

selecting one or more available transmission channels in the group based on the determined characteristics and a threshold, and

coding and modulating data for all selected transmission channels in the group based on a particular coding and modulation scheme to provide modulation symbols.

2. A method for transmitting data over multiple transmission channels in a multi-channel communication system, comprising:

coding and modulating data for transmission over transmission channels in a group of transmission channels of a plurality of groups of transmission channels to provide modulation symbols;

weighting modulation symbols for each transmission channel in each group based on a respective weight indicative of a transmit power level for the transmission channel and derived based in part on the characteristics of the transmission channel; and

transmitting the weighted modulation symbols on the selected transmission channels.

3. The method of claim 2, wherein the multi-channel communication system is a multiple-input multiple-output (MIMO) that utilizes orthogonal frequency division modulation (OFDM).

4. The method of claim 2, wherein each group corresponds to a respective transmit antenna.

5. The method of claim 2, wherein the plurality of transmission channels in each group correspond to a plurality of frequency subchannels for a corresponding transmit antenna.

6. The method of claim 2, wherein coding and modulating comprises coding and modulating the data for the selected transmission channels in each group is coded based on a common coding scheme.

7. The method of claim 6, wherein the common coding scheme is selected from among a plurality of possible coding schemes.

8. The method of claim 2, further comprising selecting one or more of the available transmission channels in each group for use for data transmission.

9. The method of claim 8, wherein selecting comprises selecting one or more of the available transmission channels in each group for use for data transmission based on the characteristics of the transmission channels and a threshold.

10. The method of claim 9, wherein each group is associated with a respective threshold.

11. The method of claim 2, fiber comprising deriving the weights for the transmission channels in each group to distribute total transmit power available for the group among all transmission channels in the group to achieve similar received signal quality.

12. The method of claim 11, wherein the received signal quality is a function of a signal-to-noise-plus-interference ratio (SNR).

13. The method of claim 2, wherein the characteristics for the available transmission channels are channel gains.

14. The method of claim 2, wherein the characteristics for the available transmission channels are received signal-to-noise-plus-interference ratios (SNRs).

15. The method of claim 2, further comprising deriving the weights for the transmission channels in each group based on a total transmit power available for the group in which the transmission channel belongs.

16. The method of claim 2, further comprising deriving the weight for each selected transmission channel based on a normalization factor, which is determined based on the characteristics of the selected transmission channels.

17. The method of claim 2, further comprising determining the characteristics of the transmission channel based upon channel state information received from an intended receiver of the weighted modulation symbols.

18. The method of claim 17, wherein the channel state information comprises information indicative of a signal-to-noise-plus-interference ratio (SNR).

19. The method of claim 17, wherein the multiple transmission channels each comprise a propagation path between each transmit-receive antenna pair for a plurality of frequency subchannels and wherein the channel state information comprises a characterization each transmission channel of the multiple transmission channels.

20. A transmitter for use in a multi-channel communication system, comprising:

a transmit data processor configured to code and modulate data for transmission over transmission channels in a group of transmission channels of a plurality of groups of transmission channels to provide modulation symbols and to weight the modulation symbols for each transmission channel in each group based on a respective weight indicative of a transmit power level for the transmission channel and derived based in part on the characteristics of the transmission channel; and

a memory coupled with the processor.

21. The transmitter of claim 20, wherein the multi-channel communication system is a multiple-input multiple-output (MIMO) that utilizes orthogonal frequency division modulation (OFDM).

22. The transmitter of claim 20, wherein each group corresponds to a respective transmit antenna of the wireless communication device.

23. The transmitter of claim 20, wherein the plurality of transmission channels in each group correspond to a plurality of frequency subchannels for a corresponding transmit antenna.

24. The transmitter of claim 20, wherein the transmit data process is configured to code and modulate the data for the selected transmission channels in each group based on a common coding scheme.

25. The transmitter of claim 20, further comprising a controller coupled with the processor and configured to select one or more of the available transmission channels in each group for use for data transmission.

26. The transmitter of claim 20, further comprising a controller coupled with the processor and configured to derive the weights for the transmission channels in each group to distribute total transmit power available for the group among all transmission channels in the group to achieve similar received signal quality.

27. The transmitter of claim 26, wherein the received signal quality is a function of a signal-to-noise-plus-interference ratio (SNR).

28. The transmitter of claim 20, wherein the characteristics for the available transmission channels are channel gains.

29. The transmitter of claim 20, wherein the characteristics for the available transmission channels are received signal-to-noise-plus-interference ratios (SNRs).

30. The transmitter of claim 20, further comprising a controller coupled with the processor and configured to derive the weights for the transmission channels in each group based on a total transmit power available for the group in which the transmission channel belongs.

31. The transmitter of claim 20, further comprising a controller coupled with the processor and configured to derive the weight for each selected transmission channel based on a normalization factor, which is determined based on the characteristics of the selected transmission channels.

32. The transmitter of claim 20, further comprising a controller coupled with the processor and configured to determine the characteristics of the transmission channel based upon channel state information received from an intended receiver of the weighted modulation symbols.

33. The transmitter of claim 20, wherein the channel state information comprises information indicative of a signal-to-noise-plus-interference ratio (SNR).

34. The transmitter of claim 20, wherein the multiple transmission channels each comprise a propagation path between each transmit-receive antenna pair for a plurality of frequency subchannels and wherein the channel state information comprises a characterization each transmission channel of the multiple transmission channels.

35. The transmitter of claim 20, wherein the transmitter comprises a transmitter of an access point.

36. The transmitter of claim 20, wherein the transmitter comprises a transmitter of an access terminal.

37. An apparatus for processing data for transmission over multiple transmission channels in a multi-channel communication system, comprising:

means for coding and modulating data for transmission over transmission channels in a group of transmission channels of a plurality of groups of transmission channels to provide modulation symbols;

means for weighting modulation symbols for each transmission channel in each group based on a respective weight indicative of a transmit power level for the transfusion channel and derived based in part on the characteristics of the transmission channel; and

a transmitter configured to transmit the weighted modulation symbols on the selected transmission channels.

38. The apparatus of claim 37, wherein the multi-channel communication system is a multiple-input multiple-output (MIMO) that utilizes orthogonal frequency division modulation (OFDM).

39. The apparatus of claim 37, wherein each group corresponds to a respective transmit antenna.

40. The apparatus of claim 37, wherein the plurality of transmission channels in each group correspond to a plurality of frequency subchannels for a corresponding transmit antenna.

41. The apparatus of claim 37, wherein the means for coding and modulating comprises means for coding and modulating the data for the selected transmission channels in each group is coded based on a common coding scheme.

42. The apparatus of claim 37, further comprising means for selecting one or more of the available transmission channels in each group for use for data transmission.

43. The apparatus of claim 37, further comprising means for deriving the weights for the transmission channels in each group to distribute total transmit power available for the group among all transmission channels in the group to achieve similar received signal quality.

44. The apparatus of claim 37, wherein the characteristics for the available transmission channels are channel gains.

45. The apparatus of claim 37, wherein the characteristics for the available transmission channels are received signal-to-noise-plus-interference ratios (SNRs).

46. The apparatus of claim 37, further comprising means for deriving the weights for the transmission channels in each group based on a total transmit power available for the group in which the transmission channel belongs.

47. The apparatus of claim 37, flanker comprising means for deriving the weight for each selected transmission channel based on a normalization factor, which is determined based on the characteristics of the selected transmission channels.

48. The apparatus of claim 37, further comprising means for determining the characteristics of the transmission channel based upon channel state information received from an intended receiver of the weighted modulation symbols.

49. A processor readable media comprising instructions thereon that may be utilized by a processor for processing data for transmission over multiple transmission channels in a multi-channel communication system, the instructions comprising:

instructions for coding and modulating data for transmission over transmission channels in a group of transmission channels of a plurality of groups of transmission channels to provide modulation symbols; and

instructions for weighting modulation symbols for each transmission channel in each group based on a respective weight indicative of a transmit power level for the transmission channel and derived based in part on the characteristics of the transmission channel.