Systems and methods are disclosed for communicating signals, by receiving a K-symbol-long input block from a 2m-ary source channel; encoding the input block into a 2m-ary non-binary low-density parity-check (LDPC) codeword of length N; and mapping each 2m-ary symbol to a point in a signal constellation comprised of 2m points, wherein a non-binary LDPC code is used as the component code for forward error correction in a coded modulation scheme capable of achieving optical fiber communication at rates beyond 100 Gb/s.