Optical trellis-coded modulation (oTCM)

@article{Bulow2004OpticalTM,
  title={Optical trellis-coded modulation (oTCM)},
  author={Henning Bulow and Gisela Thielecke and Fred Buchali},
  journal={Optical Fiber Communication Conference, 2004. OFC 2004},
  year={2004},
  volume={1},
  pages={794-}
}
In a new transmission format the output of a 10 Gb/s convolutional FEC encoder is directly mapped on an optical 10 Gbaud DQPSK signal. Versus 10 Gb/s DPSK, 4.5 dB OSNR gain is predicted without any increase of bandwidth.