Capacity achieving multicarrier modulation and coding systems and methods

1. An apparatus, comprising:

an encoder configured to perform error correction using an error correction code on a received signal to generate an encoder signal;

a shell mapper configured to perform shaping on the received signal over two or more groups of carriers with different constellation sizes to generate a shaped signal; and

a modulator configured to generate an output signal based on the encoder signal and the shaped signal.

2. The apparatus of claim 1 , the error correction code being selected from a group of forward error correction (FEC) codes.

3. The apparatus of claim 1 , the shaping including at least one of probabilistic shaping or constellation shaping.

4. The apparatus of claim 1 , the shaped signal including one or more constellation shaping bits.

5. The apparatus of claim 4 , the error correction code including an outer code, the shaping bits being protected with the outer code.

6. The apparatus of claim 1 , the error correction being performed on a subset of bits of the received signal.

7. The apparatus of claim 1 , wherein the shell mapper is disabled when the constellation size is below a threshold constellation size, the modulator being configured to adaptively generate the output signal without the shaped signal when the shell mapper is disabled.

8. The apparatus of claim 1 , the error correction code to protect one or more least significant bits (LSBs) of each constellation.

9. The apparatus of claim 1 , the error correction code in combination with interleaving is to correct at least one of an: error bursts, or an error due to an un-protected bit.

10. The apparatus of claim 1 , the shaping to be performed on fewer than all of the bits of the received signal.

11. The apparatus of claim 1 , wherein the shaping is performed based on carrier blocks of the plurality of carriers using a constant or variable number of bits per carrier.

12. The apparatus of claim 1 , wherein the shaping further includes referencing a look-up table based on a fixed number of bits to select a shell of a plurality of shells.

13. The apparatus of claim 12 , wherein constellations are to be partitioned into the plurality of shells.

14. The apparatus of claim 1 , wherein the shaping utilizes a cascade of two or more shapers to form a plurality of super groups, wherein a first shaping selects subsets of bits for each super group of the plurality of super groups and a second shaping selects shells for the selected subsets.

15. An apparatus, comprising:

a demodulation stage configured to demodulate a received signal to generate a demodulated signal, the received signal having been generated based on an encoder signal and a shaped signal;

a shell demapper configured to demap at least a subset of the demodulated signal according to a carrier group to generate a demapped signal; and

a decoder configured to decode the received signal using the demapped signal.

16. The apparatus of claim 15 , wherein the shell demapper is configured to obtain one or more shell bits for the carrier group and search the one or more shell bits to identify matching shell bits.

17. The apparatus of claim 15 , the shaped signal having been generated using at least one of probabilistic shaping or constellation shaping.

18. A method, comprising

performing error correction on a received signal using an error correction code to generate an encoder signal;

performing shaping on the received signal over two or more groups of carriers with different constellation sizes to generate a shaped signal; and

generating an output signal based on the encoder signal and the shaped signal.

19. The method of claim 18 , wherein generating the output signal includes generating one or more modulated symbols in the output signal.

20. The method of claim 18 , the error correction code in combination with interleaving is to correct at least one of an: error bursts, or an error due to an un-protected bit.