MIMO OFDM system

• US 20010053143A1
• Filed: 02/23/2001
• Published: 12/20/2001
• Est. Priority Date: 05/22/2000
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Winters, Jack Harriman, Li, Ye, Sollenberger, Nelson Ray
• Granted Patent: US 7,068,628 B2
• Time in Patent Office: Days
• US Class Current: 370/344
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

A MIMO OFDM system includes a plurality of space-time encoders for encoding respective data blocks with independent space-time codes. The transformed data block signals are transmitted by a plurality of transmit antennas and received by a plurality of receive antennas. The received data is pre-whitened prior to maximum likelihood detection. In one embodiment, successive interference cancellation can be used to improve system performance. Channel parameter estimation can be enhanced by weighting the channel impulse response estimates based upon a deviation from average.

Claims

1. A method for MIMO-OFDM communication, comprising

encoding a first data block into a first plurality of encoded signals;

encoding a second data block into a second plurality of encoded signals;

transmitting each of the first and second pluralities of encoded signals on respective transmit antennas;

receiving the transmitted signals on a plurality of receive antennas;

pre-whitening the receive signals for each of the first and second data block signals;

performing maximum likelihood detection on each of the pre-whitened received signals; and

performing successive interference cancellation on the received signals.

2. The method according to

claim 1

, further including using CRC codes to perform the successive interference cancellation.

3. The method according to

claim 1

, further including using MMSE levels to perform the successive interference cancellation.

4. The method according to

claim 1

, further including weighting channel delay response estimates.

5. The method according to

claim 4

, further including weighting the channel response estimates based upon a deviation from an average channel response estimate for each delay.

6. The method according to

claim 1

, further including minimizing an NMSE of a channel by weighting channel response estimates.

7. A method for MIMO-OFDM communication, comprising;

providing a first data block to a first space-time encoder that generates first and second coded signals;

transmitting the first coded signal from a first transmit antenna;

transmitting the second coded signal from a second transmit antenna;

providing a second data block to a second space-time encoder that generates third and fourth coded signals, wherein each of the first, second, third and fourth coded signals forms a respective OFDM block;

transmitting the third coded signal from a third transmit antenna;

transmitting the fourth coded signal from a fourth transmit antenna;

receiving the first, second, third and fourth coded signals on a plurality of receive antennas;

pre-whitening the received signals for the first data block signal;

performing maximum likelihood decoding on the pre-whitened first data block signal;

pre-whitening the received signals for the second data block signal;

performing maximum likelihood decoding on the pre-whitened second data block signal; and

regenerating the received signal, removing the first data block signal from the received signal, and re-decoding the second data block signal when the decoded first data block has a higher signal quality than the decoded second data block.

8. The method according to

claim 7

, wherein the signal quality is based upon MMSE.

9. The method according to

claim 7

, further including regenerating the received signal, removing the first data block signal from the received signal, and re-decoding the second data block signal when the decoded first data block does not have decoding errors and the second data block signal does have a decoding error.

10. The method according to

claim 7

, further including using Viterbi decoding.

11. The method according to

claim 7

, further including encoding the first and second data block signals with independent space-time codes.

12. The method according to

claim 7

, further including MMSE restoration of the first and second data block signals.

13. The method according to

claim 7

, wherein the plurality of receive antennas includes at least four receive antennas.

14. The method according to

claim 7

, further including weighting channel response estimates based upon channel delay profile information.

15. The method according to

claim 7

, further including performing a weighted DFT of estimated channel responses.

16. The method according to

claim 7

, further including computing a weighting factor corresponding to an inverse of a sum of one plus a ratio of noise power to a power of channel response estimates averaged over the receive antennas.

17. A method for MIMO-OFDM communication, comprising:

encoding a first data block into a first plurality of encoded signals;

encoding a second data block into a second plurality of encoded signals;

transmitting each of the first and second pluralities of encoded signals on respective transmit antennas;

receiving the transmitted signals on a plurality of receive antennas.

decoding the first and second data block signals; and

estimating channel parameters by weighting channel response estimates based upon a deviation from average.