Wireless communication system having error-control coder and linear precoder

• US 7,251,768 B2
• Filed: 04/21/2003
• Issued: 07/31/2007
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: University of Minnesota
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Giannakis, Georgios B., Wang, Zhengdao, Zhou, Shengli
• Primary Examiner(s): Baker, Stephen M.
• Application Number:
  US10/420,361
• Publication Number:
  US 20040022179A1
• Time in Patent Office: 1,562 Days
• Field of Search: 714/755, 714/780, 714/792, 714/786, 341/59, 375/262
• US Class Current: 714/755
• 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:

an error-control coder that applies an error correction code to produce an encoded data stream of information bearing symbols;

a bit interleaver to produce an interleaved data stream in which neighboring data bits of the encoded data stream are positioned to be mapped to different constellation symbols;

a mapping unit to map the interleaved data stream to the constellation symbols, wherein the constellation symbols are selected from a constellation having a finite alphabet;

a precoder that applies a liner transformation to the constellation symbols to produce precoded symbols, wherein the precoded symbols are complex numbers that are not restricted to the finite alphabet of the constellation;

a symbol interleaver to process the precoded symbols to produce permuted blocks of the precoded symbols; and

a modulator to produce an output waveform in accordance with the permuted blocks of precoded symbols for transmission through a wireless channel.

2. The wireless communication device of claim 1,

wherein the precoder forms blocks of M information bearing symbols from successive information bearing symbols of the encoded data steam, and

wherein the precoder linearly precodes the blocks of information bearing symbols by applying a unitary matrix of size M×

M produce corresponding linearly precoded blocks of information bearing symbols.

3. The wireless communication device of claim 1, wherein the error-control coder comprises a convolutional coder.

4. The wireless communication device of claim 1, wherein the error-control coder comprises a turbo coder.

5. The wireless communication device of claim 1, wherein the output waveform has a diversity gain that is a multiplicative function of a free distance D of the error-control coder and a symbol block size M of the linear precoder, where M is a nonzero integer.

6. 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, where M is a nonzero integer.

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

8. A wireless communication device comprising:

a demodulator that receives a waveform carrying a joint coded-linearly precoded transmission over a wireless channel and produces a demodulated data stream, wherein the joint coded-linearly precoded transmission was produced by applying an error correction code to generate an encoded data stream of information bearing symbols, mapping the information bearing symbols to constellation symbols of a constellation, and linearly precoding the information symbols by applying a linear transformation to the constellation symbols to produce precoded symbols aver a complex field without restriction to an alphabet size of the constellation;

a de-interleaver that reassembles blocks of linearly precoded symbols from the demodulated data stream; and

a decoder that applies iterative decoding techniques to decode the blocks of linearly precoded symbols and produce estimated data.

9. The wireless communication device of claim 8, wherein the decoder iteratively applies a maximum a posteriori (MAP) decoding scheme to produce the estimated data.

10. The wireless communication device of claim 8, wherein the wireless communication device comprises one of a base station and a mobile device.

11. The wireless communication device of claim 8, wherein the decoder comprises:

a symbol decoder that applies maximum a posteriori (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.

12. 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.

13. A system comprising:

a transmitter that includes;

an error-control coder that applies an error correction code to produce an encoded data stream of information-bearing symbols;

a bit interleaver to produce an interleaved data stream in which neighboring data bits of the encoded data stream are positioned to be mapped to different constellation symbols selected from a constellation having a finite alphabet;

a mapping unit to map the neighboring data bits of the encoded data stream to the different constellation symbols;

a precoder that linearly precodes the constellation symbols over a complex field without restriction to an alphabet size of the constellation to produce a joint coded-precoded data stream;

a symbol interleaver to process the precoded data stream to produce permuted blocks of precoded symbols;

a modulator to output a waveform from the permuted blocks of precoded symbols; and

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

14. The system of claim 13,

wherein the precoder forms blocks of M information bearing symbols from successive information bearing symbols of the encoded data stream, and

wherein the precoder linearly precodes the blocks of information bearing symbols by applying a unitary matrix of size M×

M to produce corresponding linearly precoded blocks of information bearing symbols.

15. The system of claim 13, wherein the error-control coder comprises a convolutional coder.

16. The system of claim 13, wherein the error-control coder comprises a turbo coder.

17. The system of claim 13, wherein the waveform has a diversity gain that is a multiplicative function of a free distance of the error-control coder and a symbol block size of the linear precoder.

18. The system of claim 13, wherein the linear precoder comprises a unitary matrix.

19. The system of claim 13, wherein the transmitter comprises a base station and the receiver comprises a mobile wireless communication device.

20. The system of claim 13, wherein the transmitter comprises a mobile wireless communication device and the receiver comprises a base station.

21. A method comprising:

encoding a data stream with an error-control code to produce an encoded data stream of information bearing symbols;

bit interleaving the encoded data stream to produce an interleaved data stream in which neighboring data bits of the encoded data stream are positioned to be mapped to different constellation symbols of a constellation having a finite alphabet;

mapping the encoded data stream to the constellation symbols;

linearly precoding the constellation symbols by applying a linear transformation to produce precoded symbols, wherein the preceded symbols are not restricted to the finite alphabet of the constellation;

processing the preceded symbols to produce permuted blocks of the preceded symbols;

modulating the permuted blocks of preceded symbols to produce an output waveform; and

transmitting the output waveform through a wireless channel.

22. The method of claim 21, wherein the error-control code comprises a convolutional code or a turbo code.

29. The method of claim 21,

wherein linearly precoding the constellation symbols comprises:

forming blocks of information beading symbols from successive ones of the information bearing symbols of the encoded data stream; and

linearly precoding complex fields of the information bearing symbols on a block-by-block basis to produce corresponding linearly precoded blocks of information bearing symbols.

23. A method comprising:

demodulating a waveform received over a wireless channel to produce a demodulated data stream, wherein the waveform was transmitted by applying an error connection code to generate an encoded data stream of information bearing symbols, bit interleaving the encoded information bearing symbols, mapping the information bearing symbols to constellation symbols of a constellation, linearly precoding the information bearing symbols by application of a linear transformation to the constellation symbols without restriction to an alphabet size of the constellation, and block interleaving the precoded information bearing symbols for transmission;

de-interleaving the demodulated data stream by reassembling blocks of linearly precoded symbols from the demodulated data; and

iteratively decoding the demodulated data stream to produce estimated data.

24. The method of claim 23, wherein iteratively decoding comprises iteratively applying a maximum a posteriori (MAP) decoding scheme to produce the estimated data.

25. The method of claim 24, 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.

26. The method of claim 24, 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.

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

encode a data stream with an error correction code to produce an encoded data stream of information bearing symbols;

interleave the encoded data stream to produce an interleaved data stream in which the information bearing symbols are permuted;

map the encoded data stream to constellation symbols;

linearly precode the information bearing symbols of the encoded data stream by applying a linear transformation to the constellation symbols to produce a precoded data stream of preceded symbols, wherein the precoded symbols are complex numbers that are not restricted to the finite alphabet of the constellation;

process the precoded data stream to produce an interleaved data stream in which blocks of the preceded symbols are permuted;

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

transmit the output waveform through a wireless channel.

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

demodulate a waveform received over a wireless channel to produce a demodulated data stream, wherein the waveform was transmitted by applying an error correction code to generate an encoded data stream of information bearing symbols, bit interleaving the encoded information bearing symbols, mapping the information bearing symbols to constellation symbols of a constellation, linearly precoding the information bearing symbols by application of a linear transformation to the constellation symbols without restriction to an alphabet size of the constellation, and block interleaving the preceded information bearing symbols for transmission;

de-interleaving the demodulated data stream by reassembling blocks of linearly precoded symbols from the demodulated data;

apply MAP decoding to the reassembled 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.