Space-time multipath coding schemes for wireless communication systems

• US 20040013180A1
• Filed: 04/21/2003
• Published: 01/22/2004
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Giannakis, Georgios B., Ma, Xiaoli
• Granted Patent: US 7,224,744 B2
• Time in Patent Office: Days
• US Class Current: 375/219
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0055 MAP-decoding
• CPC Class Codes: H04L 1/04 using frequency diversity
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Space-time multipath (STM) coding techniques are described for frequency-selective channels, respectively. The described STM coded system guarantees full space-multipath diversity, and achieves large coding gains with high bandwidth efficiency. The techniques utilize a linearly coding technique, and incorporates subchannel grouping for application of the linear coding techniques. As a result, the techniques enable desirable tradeoffs between performance and complexity.

Claims

1. A wireless communication device comprising:

a linear precoder that linearly precodes a data stream to produce a precoded data stream;

a power splitter to produce a plurality of mirrored precoded data streams from the precoded data streams; and

a plurality of antennas to output waveforms in accordance with the mirrored precoded data streams.

2. The wireless communication device of claim 1, further comprising a plurality of digital phase sweeping modules that compute a single channel vector from estimates of delay lags for each of a plurality of multi-path channels to a receiver, and process the mirrored precoded data streams with the single channel vector to shift the delay lag of each of the channels so that channel taps within the mirrored precoded data streams become consecutive.

3. The wireless communication device of claim 1, the linear precoder comprises a linear constellation precoder.

4. The wireless communication device of claim 1, wherein the linear precoder applies a unitary matrix to blocks of M symbols of the encoded data stream.

5. The wireless communication device of claim 1, further comprising a plurality of modulators to modulate each mirrored precoded data stream and produce the waveforms for transmission with the respective antennas.

6. The wireless communication device of claim 1, wherein the waveforms are multi-carrier waveforms.

7. The wireless communication device of claim 1, wherein the waveforms are single-carrier waveforms.

8. The wireless communication device of claim 1, wherein the linear precoder applies a matrix to symbol blocks of the data stream, wherein each block contains N symbols, and the matrix has a size that is an integer function of the number of antennas N_t and the estimate number (L) of multi-path channels.

9. The wireless communication device of claim 8, wherein N>

N_t*L.

10. The wireless communication device of claim 8, wherein the linear precoder divides each of the blocks of the data stream into N_g groups, where each group has N_sub symbols, and N_sub is an integer function of the number of antennas and the estimate number of multi-path channels.

11. The wireless communication device of claim 10, wherein N_sub≧

N_t*L.

12. The wireless communication device of claim 10, wherein the matrix applied by the linear precoder has a size of N_sub×

N_sub.

13. The wireless communication device of claim 10, further comprising modules to apply a permutation matrix to each of the precoded data streams to permute the symbol blocks within the mirrored precoded data streams.

14. The wireless communication device of claim 13, wherein the antennas transmit a multi-carrier waveform directly from the mirrored precoded data streams.

15. The wireless communication device of claim 14, wherein the wireless communication device transmits an orthogonal frequency division multiplexing waveform (OFDM) with each of the antennas directly from the mirrored precoded data streams without applying an inverse fast Fourier transform (IFFT) to each of the mirrored precoded data streams.

16. The wireless communication device of claim 15, wherein linear precoder applies a linear constellation precoding matrix having a dimensions of N×

N to each of the blocks of the data stream to form the precoded data stream, and the wireless communication device transmits the mirrored precoded data streams as single-carrier waveforms.

17. The wireless communication device of claim 1, wherein the wireless communication device comprises one of a base station and a mobile device.

18. A method comprising:

applying a linear precoder to a data stream to form a precoded data stream;

splitting the power of the precoded data stream to produce a plurality of mirrored precoded data streams; and

transmitting the mirrored precoded data stream with respective antennas.

19. The method of claim 18, further comprising:

estimating a delay lag for each of a plurality of multi-path channels from the transmitter to a receiver;

computing a single channel vector from the estimated delay lags for the channels; and

processing the mirrored precoded data streams with the single channel vector to shift the delay lag of each of the channels so that channel taps within the mirrored precoded data streams become consecutive.

20. The method of claim 18, wherein applying a linear precoder comprises applying a linear constellation precoder.

21. The method of claim 18, wherein transmitting the mirrored precoded data streams comprises modulating each mirrored precoded data stream to produce a set of waveforms for transmission with the respective antennas.

22. The method of claim 21, wherein the waveforms are multi-carrier waveforms.

23. The method of claim 21, wherein the waveforms are single-carrier waveforms.

24. The method of claim 18, wherein applying a linear precoder comprises:

selecting a block size N as a function of the number of antennas N_t and an estimate number L of multi-path channels to a receiver; and

applying a matrix to symbol blocks of the data stream, wherein the matrix has a size that is selected as a function of the number of antennas and the estimate number of multi-path channels.

25. The method of claim 24, wherein N>

N_t*L.

26. The method of claim 24, wherein applying a linear precoder comprises:

dividing each of the blocks of the data stream into N_g groups, where each group has N_sub symbols, and N_sub is selected as a function of the number of antennas and the estimate number of multi-path channels; and

applying the matrix to each of the symbol groups within the blocks, wherein the matrix has a dimension that is a function of the number of symbols N_sub within the groups.

27. The method of claim 26, wherein N_sub≧

N_t*L.

28. The method of claim 26, wherein a size of the matrix is N_sub×

N_sub.

29. The method of claim 24, wherein transmitting the mirrored precoded data streams comprises:

applying a permutation matrix to each of the precoded data streams to permute the blocks within the precoded data streams; and

transmitting a multi-carrier waveform with each of the antennas directly from the permuted precoded data streams.

30. The method of claim 29, wherein transmitting a multi-carrier waveform comprises transmitting an orthogonal frequency division multiplexing waveform (OFDM) with each of the antennas directly from the permuted precoded data streams without applying an inverse fast Fourier transform (IFFT) to each of the precoded data streams.

31. The method of claim 30, wherein applying a matrix comprises applying a matrix having a dimensions of N×

N to each of the blocks of the data stream to form the precoded data stream.

32. The method of claim 18, wherein transmitting the mirrored precoded data streams comprises transmitting each of the mirrored precoded data streams as a single-carrier waveform with a respective one of the antennas.

33. A computer-readable medium comprising instructions to cause a programmable processor of a wireless communication device to:

apply a linear precoder to a data stream to form a precoded data stream;

split the power of the precoded data stream to produce a plurality of mirrored precoded data streams; and

transmit the mirrored precoded data stream with respective antennas.

34. The computer-readable medium of claim 33, further comprising instructions to cause the programmable processor to:

estimate a delay lag for each of a plurality of multi-path channels from the transmitter to a receiver;

compute a single channel vector from the estimated delay lags for the channels; and

process the mirrored precoded data streams with the single channel vector to shift the delay lag of each of the channels so that channel taps within the mirrored precoded data streams become consecutive.

35. The computer-readable medium of claim 33, further comprising instructions to cause the programmable processor to:

select a block size N as a function of the number of antennas N_t and an estimate number L of multi-path channels to a receiver; and

apply a matrix to symbol blocks of the data stream, wherein the matrix has a size that is selected as a function of the number of antennas and the estimate number of multi-path channels.

36. A method comprising:

linearly encoding blocks of N symbols a data stream with a matrix to form a precoded data stream, wherein N is an integer function of the number of antennas N_t of a transmitter and an estimate number L of multi-path channels from the transmitter to a receiver; and

transmitting the precoded data stream with the antennas.