Symbol-level interleaving to mitigate error propagation of TCM-16QAM in nonlinear fiber transmissions

Decoding of trellis-coded modulation 16-ary quadrature amplitude (TCM-16QAM) after nonlinear fiber transmissions suffers from error propagation. To mitigate the effect, we propose a simple method of symbol-level interleaving based on a transpose operation. In a transmission experiment of 32-GBaud TCM-16QAM over 3×80-km standard single-mode fibers, at a bit error ratio (BER) of 1E−3, the launch power of the interleaved TCM signal can be increased by 0.7 and 1.0 dB in the fiber-nonlinear region, compared to 8PSK and TCM-16QAM without interleaving, respectively.