Pilot-Aided Trellis-Based Demodulation

In optical transmission systems based on high-order modulations, the impact on system performance of Wiener phase noise affecting the received carrier phase can be relevant. To make less severe phase noise effects, solutions based on the use of known pilot symbols, that aid carrier phase recovery, have been recently introduced. This letter proposes a pilot-aided demodulation scheme where the memory of phase noise is dealt with by a trellis-based demodulation algorithm. The benefits in terms of achievable information rate and bit error rate compared to adversary schemes are demonstrated by computer simulations for strong phase noise with 4-ary quadrature amplitude modulation (4-QAM) and 16-QAM.