Turbo coding for upstream and downstream transmission in cable systems
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 transmitting first data and receiving second data in a cable modem system comprising the steps of:
encoding the first data using a forward error correction (FEC) scheme to generate FEC encoded data;
encoding the FEC encoded data using a Turbo encoding scheme to generate Turbo encoded data;
mapping the Turbo encoded data to a modulation scheme to generate mapped data;
transmitting the mapped data over a cable channel;
demodulating the second data received over the cable channel to generate demodulated data;
decoding the demodulated data using a Turbo decoding scheme to generate Turbo decoded data, wherein symbol estimates for the Turbo decoded data are generated using between 8 and 16 iterations; and
decoding the turbo decoded data using the FEC decoding scheme.
2. The method of claim 1 , further including the step of interleaving the FEC encoded data before encoding the FEC encoded data using the Turbo encoding scheme.
3. The method of claim 1 , wherein the step of encoding the FEC encoded data using the Turbo encoding scheme includes using a convolutional encoder.
4. The method of claim 1 , wherein the step of encoding the FEC encoded data using the Turbo encoding scheme includes the step of interleaving the FEC encoded data.
5. The method of claim 1 , further including the step of framing the first data into MPEG frames prior to the step of encoding the first data using the FEC scheme.
6. The method of claim 1 , wherein the FEC scheme is a block code.
7. The method of claim 1 , wherein the FEC scheme is a trellis code.
8. The method of claim 1 , wherein the Turbo encoding scheme uses an RSC (Recursive Systematic Convolutional) code.
9. The method of claim 1 , wherein the Turbo encoding scheme uses an NSC (Non-Systematic Convolutional) code.
10. The method of claim 1 , wherein the Turbo encoding scheme is implemented using a first constituent encoder and a second constituent encoder, wherein the FEC encoded data is fed into the first and second constituent encoders in an interleaved manner.
11. The method of claim 10 , wherein the interleaved manner includes using a pseudo-random interleaver.
12. The method of claim 10 , wherein the interleaved manner includes using a one-for-one interleaver.
13. The method of claim 1 , wherein the symbol estimates are provided in probabilistic form to an external circuit.
14. The method of claim 1 , wherein the Turbo decoding scheme uses a soft input/soft output algorithm.
15. A system for transmitting first data and receiving second data in a cable modem system comprising:
a forward error correction (FEC) block configured to encode the first data to generate FEC encoded data;
a Turbo encoder that is configured to encode data from the forward error correction block to generate Turbo encoded data;
a modulator that is configured to map the Turbo encoded data to a modulation scheme to generate mapped data;
a cable modem transmitter that is configured to transmit the mapped data over a cable channel;
a demodulator that is configured to demodulate the second data received over the cable channel to generate demodulated data;
a Turbo decoder that is configured to decode the demodulated data to generate Turbo decoded data, wherein symbol estimates for the Turbo decoded data are configured to be generated using between 8 and 16 iterations; and
a forward error correction decoder that is configured to decode the Turbo decoded data.
16. The system of claim 15 , further including an interleaver that is configured to interleave the FEC encoded data before the FEC encoded data is encoded by the Turbo encoder.
17. The system of claim 15 , wherein the Turbo encoder includes a convolutional encoder.
18. The system of claim 15 , wherein the Turbo encoder includes an interleaver that is configured to receive the FEC encoded data inputted into the Turbo encoder.
19. The system of claim 15 , further including an MPEG framer configured to receive the data prior to the FEC block.
20. The system of claim 15 , wherein the FEC block uses a block code.
21. The system of claim 15 , wherein the FEC block uses a trellis code.
22. The system of claim 15 , wherein the Turbo encoder uses an RSC (Recursive Systematic Convolutional) code.
23. The system of claim 15 , wherein the Turbo encoder uses an NSC (Non-Systematic Convolutional) code.
24. The system of claim 15 , wherein the Turbo encoder includes a first constituent encoder and a second constituent encoder, wherein the FEC encoded data is fed into the first and second constituent encoders in an interleaved manner.
25. The system of claim 24 , wherein the interleaved manner includes using a pseudo-random interleaver.
26. The system of claim 24 , wherein the interleaved manner includes using a one-for-one interleaver.
27. The system of claim 15 , wherein the symbol estimates are provided in probabilistic form to an external circuit.
28. The system of claim 15 , wherein the Turbo decoder uses a soft input/soft output algorithm.