Systems and methods for retransmission return channel error detection

1. A system comprising:

a transmitter for transmitting a coded message to a far-end coded message receiver, the transmitter comprising:

an encoder configured to encode a message into a coded message having information bits and redundancy bits, the encoder using a generator matrix [I P], where I is an identity matrix that passes the information bits from the message into the encoded message and P represents a matrix that generates the redundancy bits in the encoded message from the information bits in the message; and

a modulator configured to modulate the encoded message to one or more tones forming a discrete multi-tone (DMT) symbol using a modulation scheme comprising a constellation size, wherein the P matrix and the constellation size of the modulation scheme are jointly determined so that the combination of the determined P matrix and constellation size of the modulation scheme together minimize a misdetection probability at the far-end coded message receiver.

2. The system of claim 1 , wherein the transmitter is configured to minimize the misdetection probability by selecting the modulation scheme to minimize the message error probability and then selecting the P matrix that maximizes both Hamming and Euclidean minimum distances on the coded message.

3. The system of claim 1 , wherein the transmitter is configured to minimize the misdetection probability by first selecting a modulation scheme to minimize the message error probability.

4. The system of claim 3 , wherein the message error probability is minimized by modulating the coded message to tones with a signal-to-noise ratio (SNR) higher than the minimum required SNR.

5. The system of claim 3 , wherein upon selecting a modulation scheme, the transmitter then selects the P matrix that maximizes a Hamming minimum distance and minimizes multiplicities associated with smallest Euclidean distances of a Euclidean distance spectrum computed for the coded message.

6. The system of claim 1 , wherein the linear block code P matrix is communicated by the far-end coded message receiver.

7. The system of claim 1 , wherein configuration of the modulator is specified by the far-end message receiver.

8. The system of claim 1 , wherein the joint determination of the P matrix and modulation scheme is performed according to a noise environment.

9. The system of claim 7 , wherein the configuration of the modulator comprises bit-to-tone loading information.

10. The system of claim 1 , wherein the modulator operates based on a trellis coded modulation (TCM) scheme, wherein the message error probability is minimized by modulating the coded message including the TCM redundancy to a first trellis section of a TCM trellis diagram.

11. A system comprising:

a receiver for receiving a coded message from a far-end coded message transmitter, the receiver comprising:

an error detector configured to determine a level of correctness of the received message encoded to include information bits and redundancy bits, the encoding having been performed using a generator matrix [I P], where I is an identity matrix that passes the information bits into the encoded message and P represents a matrix that generates the redundancy bits in the encoded message; and

a demodulator configured to demodulate the encoded message from one or more tones forming a discrete multi-tone (DMT) symbol using a demodulation scheme comprising a constellation size; and

wherein the receiver is further configured to transmit modulation information associated with the coded message to the far-end message transmitter, and wherein the receiver jointly determines the P matrix and modulation information including the constellation size so that the combination of the determined P matrix and constellation size together minimize a misdetection probability.

12. The system of claim 11 , wherein the P matrix is communicated to the far-end coded message transmitter.

13. The system of claim 11 , wherein the demodulator comprises a trellis coded modulation (TCM) scheme decoder.

14. The system of claim 13 , wherein the receiver minimizes the message error probability by transmitting to the far-end transmitter, modulation information to modulate the coded message including the TCM redundancy to a first trellis section of a TCM trellis diagram.

15. The system of claim 11 , wherein the receiver minimizes the message error probability by transmitting to the far-end transmitter, modulation information to modulate the coded message to tones with a signal-to-noise ratio (SNR) higher than the minimum required SNR.

16. The system of claim 11 , wherein the receiver minimizes the misdetection probability by first selecting a modulation scheme that minimizes the message error probability.

17. The system of claim 16 , wherein upon selecting a modulation scheme, the receiver then selects the P matrix that maximizes both Hamming and Euclidean minimum distances computed for the coded message.

18. The system of claim 16 , wherein upon selecting a modulation scheme, the receiver then selects the P matrix that maximizes the Hamming minimum distance and minimizes multiplicities associated with smallest Euclidean distances of a Euclidean distance spectrum computed for the coded message.

19. A system according to claim 1 ,

wherein the identity matrix I is a 12*12 identity matrix, and

wherein the P matrix is:

P

=

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]

.

20. A system according to claim 11 ,

wherein the identity matrix I is a 12*12 identity matrix, and

wherein the P matrix is:

P

=

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]

.

21. A method implemented in a digital subscriber line (DSL) system for minimizing a misdetection probability at a far-end coded message receiver during transmission of a coded message, comprising:

jointly determining, at the far-end coded message receiver, a P matrix and a modulation scheme comprising a constellation size, wherein jointly determining includes determining a combination of P matrix and constellation size that together minimize the misdetection probability;

encoding a message into a coded message having information bits and redundancy bits using a generator matrix [I P], where I is an identity matrix that passes the information bits from the message into the encoded message and P represents the determined P matrix that generates the redundancy bits from the information bits in the message; and

modulating the encoded message to one or more tones forming a discrete multi-tone (DMT) symbol according to the determined modulation scheme.

22. The method of claim 21 , wherein jointly determining a P matrix and a modulation scheme comprises:

selecting a modulation scheme; and

upon selecting the modulation scheme, selecting the P matrix that maximizes both Hamming and Euclidean minimum distances, wherein the minimum Euclidean distance is computed for the coded message.