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

• US 8,477,858 B2
• Filed: 02/25/2010
• Issued: 07/02/2013
• Est. Priority Date: 05/17/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ketchum, John W., Howard, Steven J., Walton, Jay Rod, Wallace, Mark S., Ling, Fuyun
• Primary Examiner(s): Puente, Eva
• Application Number:
  US12/713,121
• Publication Number:
  US 20100246704A1
• Time in Patent Office: 1,223 Days
• Field of Search: 375/260, 375/367, 375/267
• US Class Current: 375/260
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• 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 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 5/0046 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 5/06 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 a set of transmission channels selected from among all available transmission channels. In an aspect, the data processing includes coding data based on a common coding and modulation scheme to provide modulation symbols and pre-weighting the modulation symbols for each selected channel based on the channel'"'"'s characteristics. The pre-weighting may be achieved by “inverting” the selected channels so that the received SNRs are approximately similar for all selected channels. With selective channel inversion, only channels having SNRs at or above a particular threshold are selected, “bad” channels are not used, and the total available transmit power is distributed across only “good” channels. Improved performance is achieved due to the combined benefits of using only the NS best channels and matching the received SNR of each selected channel to the SNR required by the selected coding and modulation scheme.

Claims

1. A method for transmitting data by a transmitter over multiple transmission channels to a receiver in a wireless multiple-input multiple-output (MIMO) multi-channel communication system that uses orthogonal frequency division modulation (OFDM), comprising:

selecting a plurality of available transmission channels for use for data transmission, wherein the selected transmissions channels have signal-to-interference-plus-noise ratios at or above a threshold value, wherein the signal-to-interference-plus-noise ratios are calculated based on channel state information (CSI) received from the receiver;

coding and modulating data for transmission over the selected transmission channels using a common coding and modulation scheme selected from a plurality of available coding and modulation schemes to provide modulation symbols, the common coding and modulation scheme resulting in approximately the same bit rate for each selected channel;

weighting the modulation symbols for each selected transmission channel based on channel state information (CSI) for the selected channels, in an effort to distribute the total available transmit power across the selected transmission channels to achieve similar received signal quality at the receiver; and

transmitting the weighted modulation symbols on the selected transmission channels.

2. The method of claim 1, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a respective transmit antenna.

3. The method of claim 1, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a plurality of frequency subchannels for a corresponding transmit antenna.

4. The method of claim 1, further comprising deriving the weight for each selected transmission channel based on a normalization factor, which is determined based on the signal-to-interference-plus-noise ratios of the selected transmission channels.

5. A transmitter for use in a wireless multiple-input multiple-output (MIMO) multi-channel communication system that uses orthogonal frequency division modulation (OFDM), comprising:

a controller configured to select a plurality of available transmission channels for use for data transmission, wherein the selected transmissions channels have signal-to-interference-plus-noise ratios at or above a threshold value, wherein the signal-to-interference-plus-noise ratios are calculated based on channel state information (CSI) received from a receiver;

a transmit data processor configured to;

code and modulate data for transmission over the selected transmission channels using a common coding and modulation scheme selected from a plurality of available coding and modulation schemes to provide modulation symbols, wherein use of the common coding and modulation scheme results in approximately the same bit rate for each selected channel,

weight the modulation symbols for each selected transmission channel based on channel state information (CSI) for the selected channels, in an effort to distribute the total available transmit power across the selected transmission channels to achieve similar received signal quality at the receiver, and

transmit the weighted modulation symbols on the selected transmission channels.

6. The transmitter of claim 5, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a respective transmit antenna.

7. The transmitter of claim 5, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a plurality of frequency subchannels for a corresponding transmit antenna.

8. The transmitter of claim 5, further comprising logic configured to derive the weight for each selected transmission channel based on a normalization factor, which is determined based on the signal-to-interference-plus-noise ratios of the selected transmission channels.

9. An apparatus for transmitting data by a transmitter over multiple transmission channels to a receiver in a wireless multiple-input multiple-output (MIMO) multi-channel communication system that uses orthogonal frequency division modulation (OFDM), comprising:

means for selecting a plurality of available transmission channels for use for data transmission, wherein the selected transmissions channels have signal-to-interference-plus-noise ratios at or above a threshold value, wherein the signal-to-interference-plus-noise ratios are calculated based on channel state information (CSI) received from a receiver;

means for coding and modulating data for transmission over the selected transmission channels using a common coding and modulation scheme selected from a plurality of available coding and modulation schemes to provide modulation symbols, wherein use of the common coding and modulation scheme results in approximately the same bit rate for each selected channel;

means for weighting the modulation symbols for each selected transmission channel based on channel state information (CSI) for the selected channels, in an effort to distribute the total available transmit power across the selected transmission channels to achieve similar received signal quality at the receiver; and

means for transmitting the weighted modulation symbols on the selected transmission channels.

10. The apparatus of claim 9, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a respective transmit antenna.

11. The apparatus of claim 9, wherein the available transmission channels are selected from one of a group of transmission channels and each group corresponds to a plurality of frequency subchannels for a corresponding transmit antenna.

12. The apparatus of claim 9, further comprising means for deriving the weight for each selected transmission channel based on a normalization factor, which is determined based on the signal-to-interference-plus-noise ratios of the selected transmission channels.