Wireless communication system having error-control coder and linear precoder

• US 20040022179A1
• Filed: 04/21/2003
• Published: 02/05/2004
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: University of Minnesota
• Original Assignee: University of Minnesota
• Inventors: Zhou, Shengli, Giannakis, Georgios B., Wang, Zhengdao
• Granted Patent: US 7,251,768 B2
• Time in Patent Office: Days
• US Class Current: 370/207
• CPC Class Codes: H03M 13/29 combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
• CPC Class Codes: H03M 13/2948 Iterative decoding H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H03M 13/6513 Support of multiple code types, e.g. unified decoder for LDPC and turbo codes
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/0055 MAP-decoding
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/04 using frequency diversity

Abstract

In general, joint error-control coding and linear precoding techniques are proposed for fading-resilient transmissions over frequency- at and frequency-selective fading channels encountered with high-rate wireless OFDM transmissions. For example, a wireless communication system includes a transmitter that applies non-linear codes and a linear precoder to a data stream to produce a joint coded-precoded waveform. A receiver receives the joint coded-precoded waveform from the transmitter via a wireless communication channel, and demodulates the joint-coded precoded waveform to produce estimated data. The combination offers a multiplicative benefit to the diversity achievable by the wireless communication system.

Claims

1. A wireless communication device comprising:

a non-linear coder that encodes a data stream to produce an encoded data stream;

a precoder that linearly precodes the encoded data stream to produce a precoded data stream; and

a modulator to produce an output waveform in accordance with the precoded data stream for transmission through a wireless channel.

2. The wireless communication device of claim 1, wherein the non-linear coder uses error-control codes to encode the data stream.

3. The wireless communication device of claim 2, wherein the non-linear coder comprises a convolutional coder.

4. The wireless communication device of claim 2, wherein the non-linear coder comprises a turbo coder.

5. The wireless communication device of claim 1, further comprising a mapping unit to map the encoded data stream to constellation symbols.

6. The wireless communication device of claim 5, further comprising a bit interleaver to produce an interleaved data stream in which data bits of the encoded data stream are separated to cause the mapping unit to map neighboring bits to different ones of the constellation symbols.

7. The wireless communication device of claim 1, further comprising a symbol interleaver to process information symbols of the precoded data stream to produce an interleaved data stream in which blocks of information symbols are permuted within the interleaved data stream.

8. The wireless communication device of claim 1, the output waveform has a diversity gain that is multiplicative function of a free distance D of the non-linear coder and a symbol block size M of the linear precoder.

9. 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.

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

11. A wireless communication device comprising:

a demodulator that receives a waveform carrying a joint coded-linearly precoded transmission and produces a demodulated data stream; and

a decoder that applies iterative decoding techniques to decode the demodulated data and produce estimated data.

12. The wireless communication device of claim 11, wherein the decoder iteratively applies a maximum a posteriori (MAP) decoding scheme to produce the estimated data.

13. The wireless communication device of claim 11, wherein the decoder comprises:

a symbol decoder that applies MAP decoding to blocks of symbols within the demodulated data stream to produce soft symbol information; and

a bit decoder that receives the soft symbol information and applies MAP decoding to produce soft bit information and the estimated data, wherein the soft bit information is fed back to the symbol decoder for computation of the soft symbol information.

14. The wireless communication device of claim 11, wherein the symbol decoder and the bit decoder iteratively produce the soft symbol information and the soft bit information to compute the estimated data.

15. The wireless communication device of claim 11, wherein the wireless communication device comprises one of a base station and a mobile device.

16. A system comprising:

a transmitter that applies non-linear codes and a linear precoder to a data stream to produce a joint coded-precoded waveform; and

a receiver that receives the joint coded-precoded waveform from the transmitter via a wireless communication channel, and demodulates the joint-coded precoded waveform to produce estimated data.

17. The system of claim 16, wherein the non-linear codes comprise error-control codes.

18. The system of claim 16, wherein the non-linear codes comprise convolutional codes.

19. The system of claim 16, wherein the non-linear codes comprises turbo codes.

20. The system of claim 16, wherein the joint coded-precoded waveform has a diversity gain that is multiplicative function of a free distance D of the non-linear coder and a symbol block size M of the linear precoder.

21. The system of claim 16, wherein the linear precoder comprises a unitary matrix.

22. The system of claim 16, wherein the transmitter comprises a base station and the receiver comprises a mobile wireless communication device.

23. The system of claim 16, wherein the transmitter comprises a mobile wireless communication device and the receiver comprises a base station.

24. A method comprising:

encoding a data stream with non-linear codes to produce an encoded data stream; and

applying a linear precoder to the encoded data stream to produce a precoded data stream.

25. The method of claim 24, further comprising:

modulating the precoded data stream to produce an output waveform; and

transmitting the output waveform through a wireless channel.

26. The method of claim 24, wherein encoding a data stream comprises encoding the data stream with at least one of error-control codes, convolutional codes, and turbo codes.

27. The method of claim 24, further comprising mapping the encoded data stream to constellation symbols.

28. The method of claim 27, further comprising processing the encoded data stream with a bit interleaver to produce an interleaved data stream in which data bits of the encoded data stream are separated to cause neighboring bits to be mapped to different ones of the constellation symbols.

29. The method of claim 24, further comprising processing the precoded data stream with a symbol interleaver to permute blocks of information symbols of the precoded data stream.

30. A method comprising:

demodulating a waveform carrying a joint coded-linearly precoded transmission to produce a demodulated data stream; and

iteratively decoding the demodulated data to produce estimated data.

31. The method of claim 30, wherein iteratively decoding comprises iteratively applying a maximum a posteriori (MAP) decoding scheme to produce the estimated data.

32. The method of claim 31, wherein iteratively applying a maximum a posteriori (MAP) decoding scheme comprises:

applying MAP decoding to blocks of symbols within the demodulated data stream to compute soft symbol information;

applying MAP decoding to the soft symbol information to compute soft bit information; and

outputting the estimated data based on the soft bit information.

33. The method of claim 30, wherein iteratively applying a maximum a posteriori (MAP) decoding scheme further comprises applying the MAP decoding to the blocks of symbols as a function of feedback information that includes at least a portion of the computed soft bit information.

34. A computer-readable medium comprising instructions to cause a programmable processor to:

encode a data stream with non-linear codes to produce an encoded data stream;

apply a linear precoder to the encoded data stream to produce a precoded data stream;

modulate the precoded data stream to produce an output waveform; and

transmit the output waveform through a wireless channel.

35. A computer-readable medium comprising instructions to cause a programmable processor to:

demodulate a waveform carrying a joint coded-linearly precoded transmission to produce a demodulated data stream;

apply MAP decoding to blocks of symbols within the demodulated data stream to compute soft symbol information;

apply MAP decoding to the soft symbol information to compute soft bit information; and

output estimated data based on the soft bit information.