Side Band Pilot Tone for Digital Signal Processing in Polarization Multiplexed Coherent Optical Communication System

An apparatus comprising:

• at least one processor coupled to a memory and configured to:
• obtain a data block that comprises a plurality of side band pilot tones (SBPTs) in a received polarization multiplexed (PM) optical signal;
• estimate a set of values for a carrier frequency and a polarization state;
• update a tap weight of a master equalizer based on the estimated set of values;
• and
• update a plurality of slave equalizers based on the updated tap weight of the master equalizer.

An apparatus comprising:

• a master processor configured to estimate phase and carrier frequency in a first portion of a received signal;
• a plurality of slave processors configured to estimate phase and carrier frequency in a plurality of second portions of the received signals;
• a demultiplexer coupled to each of the master processor and the slave processors and configured to distribute the first portion and the second portions in parallel between the first processor and the slave processors;
• a plurality of carrier recovery units coupled in parallel to the master processor and the slave processors;
• a plurality of decoder units coupled in parallel to the carrier recovery units;
• and
• a tap weight calculator coupled to the master processor and one of the decoders that corresponds to the master processor and configured to update the tap weight of master and slave equalizers.