Data transmission with spatial spreading in a MIMO communication system

• US 7,764,754 B2
• Filed: 12/21/2007
• Issued: 07/27/2010
• Est. Priority Date: 12/09/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Walton, J. Rodney, Wallace, Mark S.
• Primary Examiner(s): Ghebretinsae; Temesghen
• Application Number:
  US11/963,199
• Publication Number:
  US 20080095282A1
• Time in Patent Office: 949 Days
• Field of Search: 375/347, 375/147, 375/267
• US Class Current: 375/347
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• 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 25/0224 using sounding signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

For data transmission with spatial spreading, a transmitting entity (1) encodes and modulates each data packet to obtain a corresponding data symbol block, (2) multiplexes data symbol blocks onto NS data symbol streams for transmission on NS transmission channels of a MIMO channel, (3) spatially spreads the NS data symbol streams with steering matrices, and (4) spatially processes NS spread symbol streams for full-CSI transmission on NS eigenmodes or partial-CSI transmission on NS spatial channels of the MIMO channel. A receiving entity (1) obtains NR received symbol streams via NR receive antennas, (2) performs receiver spatial processing for full-CSI or partial-CSI transmission to obtain NS detected symbol streams, (3) spatially despreads the NS detected symbol streams with the same steering matrices used by the transmitting entity to obtain NS recovered symbol streams, and (4) demodulates and decodes each recovered symbol block to obtain a corresponding decoded data packet.

Claims

1. A memory unit having a set of instructions stored thereon, the set of instructions being executable by one or more processors and the set of instructions comprising:

instructions for obtaining a plurality of streams of received symbols for a plurality of streams of data symbols transmitted via a plurality of transmission channels in a MIMO channel, wherein the plurality of streams of data symbols are spatially spread with a plurality of steering matrices and further spatially processed prior to transmission via the MIMO channel, and wherein the spatial spreading with the plurality of steering matrices randomizes the plurality of transmission channels for the plurality of streams of data symbols;

instructions for performing receiver spatial processing on the plurality of streams of received symbols to obtain a plurality of streams of detected symbols; and

instructions for performing spatial despreading on the plurality of streams of detected symbols with the plurality of steering matrices to obtain a plurality of streams of recovered symbols, which are estimates of the plurality of streams of data symbols.

2. The memory unit of claim 1, further comprising:

instructions for obtaining an effective MIMO channel estimate that includes a channel response estimate for the MIMO channel and the plurality of steering matrices used for spatial spreading; and

instructions for performing the receiver spatial processing and the spatial despreading jointly based on the effective MIMO channel estimate.

3. The memory unit of claim 1, wherein the instructions for performing spatial despreading comprise:

instructions for performing spatial despreading on each block of detected symbols in the plurality of streams of detected symbols with at least two steering matrices used by a transmitting entity on a corresponding block of data symbols.

4. The memory unit of claim 1, wherein the instructions for performing spatial despreading comprise:

instructions for performing spatial despreading on the plurality of streams of detected symbols using a set of L steering matrices, where L is an integer greater than one, and wherein the L steering matrices are unitary matrices.

5. The memory unit of claim 1, wherein the instructions for performing receiver spatial processing comprise:

instructions for multiplying the plurality of streams of received symbols with matrices of eigenvectors for a plurality of eigenmodes of the MIMO channel to obtain the plurality of streams of detected symbols.

6. The memory unit of claim 1, wherein the instructions for performing receiver spatial processing comprise:

instructions for deriving a matched filter based on a channel response estimate for the MIMO channel, and

instructions for multiplying the plurality of streams of received symbols with the matched filter to obtain the plurality of streams of detected symbols.

7. The memory unit of claim 1, wherein the instructions for performing receiver spatial processing comprise:

instructions for performing receiver spatial processing on the plurality of streams of received symbols based on a channel correlation matrix inversion (CCMI) technique.

8. The memory unit of claim 1, wherein the instructions for performing receiver spatial processing comprise:

instructions for performing receiver spatial processing on the plurality of streams of received symbols based on a minimum mean square error (MMSE) technique.

9. The memory unit of claim 1, wherein the instructions for performing receiver spatial processing comprise:

instructions for performing receiver spatial processing on the plurality of streams of received symbols based on a successive interference cancellation (SIC) technique.

10. The memory unit of claim 1, further comprising:

instructions for estimating a signal-to-noise-and-interference ratio (SNR) of each of the plurality of transmission channels for the plurality of streams of data symbols; and

instructions for selecting a rate for each of the plurality of streams of data symbols based on an SNR estimate for the transmission channel for the stream of data symbols.

11. The memory unit of claim 1, further comprising:

instructions for sending to the transmitting entity at least one rate for the plurality of streams of data symbols, wherein the plurality of streams of data symbols are encoded and modulated based on the at least one rate.

12. The memory unit of claim 1, further comprising:

instructions for estimating a signal-to-noise-and-interface ratio (SNR) of each of the plurality of transmission channels for the plurality of streams of data symbols; and

instructions for selecting a single rate for the plurality of streams of data symbols based on SNR estimates for the plurality of transmission channels.

13. The memory unit of claim 1, further comprising:

instructions for demodulating and decoding each of the plurality of streams of recovered symbols based on a rate selected for the stream to obtain decoded data.

14. The memory unit of claim 1, wherein the instructions for performing spatial despreading comprise:

instructions for performing spatial despreading on the plurality of streams of detected symbols with at least two steering matrices for a plurality of subbands of each symbol period used for data transmission.