Performance Evaluation of Trellis Code Modulated oDQPSK Using the KLSE Method

A direct detection optical differential quadrature phase-shift keying (oDQPSK) system with trellis coded modulation (TCM) is proposed and analyzed. From the results obtained for the symbol-error rate, it is observed that the proposed oDQPSK-TCM system can perform about 5 dB better than the uncoded oDQPSK system. Optical signal-to-noise ratio penalty due to first-order polarization-mode dispersion of the proposed oDQPSK-TCM system is evaluated and compared with that of unequalized as well as electrically equalized oDQPSK systems.