Turbo coding for upstream and downstream transmission over a channel
View Patent ↗A method of transmitting data in a cable modem system includes the steps of encoding the data using forward error correction. The data is then encoded with Turbo encoding. The data is then sent to a modulation scheme. The data is then transmitted over a cable channel. The data is then demodulated. The data is then decoded using a Turbo decoder. An inverse of the forward error correction is then applied to the data.
1. A method of encoding data for transmission over a channel comprising:
encoding the data using an outer, forward error correction (FEC) scheme to generate a first portion of outer encoded data and a second portion of outer encoded data;
encoding the first portion of outer encoded data using an inner encoding scheme to generate inner encoded data; and
mapping the second portion of outer encoded data and the inner encoded data to a modulation scheme to generate mapped data for transmission over the channel.
2. The method of claim 1 , further including interleaving the first portion of outer encoded data before encoding the first portion of outer encoded data using the inner encoding scheme.
3. The method of claim 1 , wherein the encoding the first portion of outer encoded data using the inner encoding scheme includes using a convolutional encoder.
4. The method of claim 1 , wherein the encoding the first portion of outer encoded data using the inner encoding scheme includes interleaving the first portion of outer encoded data.
5. The method of claim 1 , wherein the outer, FEC scheme is a block code or a trellis code.
6. The method of claim 1 , wherein the inner encoding scheme uses an RSC (Recursive Systematic Convolutional) code or an NSC (Non-Systematic Convolutional) code.
7. The method of claim 1 , wherein the inner encoding scheme: implemented using a first constituent encoder and a second constituent encoder, wherein the first portion of outer encoded data is fed into the first and second constituent encoders in an interleaved manner.
8. A system for encoding data for transmission over a channel comprising:
an outer, forward error correction (FEC) block configured to encode the data to generate a first portion of outer encoded data and a second portion of outer encoded data;
an inner encoder configured to encode the first portion of outer encoded data to generate inner encoded data; and
a modulator configured to map the second portion of outer encoded data and the inner encoded data to a modulation scheme to generate mapped data for transmission over the channel.
9. The system of claim 8 , further including an interleaver configured to interleave the first portion of outer encoded data before the first portion of outer encoded data is encoded by the inner encoder.
10. The system of claim 8 , wherein the inner encoder includes a convolutional encoder.
11. The system of claim 8 , wherein the inner encoder includes an interleaver configured to receive the first portion of outer encoded data inputted into the inner encoder.
12. The system of claim 8 , wherein the outer, FEC block uses a block code or a trellis code.
13. The system of claim 8 , wherein the inner encoder uses an RSC (Recursive Systematic Convolutional) code or an NSC (Non-Systematic Convolutional) code.
14. The system of claim 8 , wherein the inner encoder includes a first constituent encoder and a second constituent encoder, wherein the first portion of outer encoded data is fed into the first and second constituent encoders in an interleaved manner.
15. The system of claim 14 , wherein the interleaved manner includes using a pseudo-random interleaver or a one-for-one interleaver.
16. A system for decoding data received over a channel comprising:
a demodulator configured to demodulate the received data to generate a first portion of demodulated data and a second portion of demodulated data;
an inner decoder configured to decode the first portion of demodulated data to generate inner decoded data;
an outer, forward error correction (FEC) decoder configured to decode the inner decoded data and the second portion of demodulated data.
17. The system of claim 16 , wherein the inner decoder is configured to generate the inner decoded data as symbol estimates.
18. The system of claim 17 , wherein the inner decoder is configured to provide the symbol estimates in probabilistic form to an external circuit.
19. The system of claim 16 , wherein the inner decoder uses a soft input/soft output algorithm.
20. The system of claim 16 , wherein the inner decoder is an iterative decoder.