Advanced techniques to improving the transmission capacity of passive optical networks

The development of new services and the expansion of legacy services are constantly increasing the demands on access networks. Passive optical networks can meet these increasing demands by develop a new standard and improve existing optical networks. Currently, next generation passive optical networks provide sufficient transmission capacity while allowing legacy standards to coexist. One way to improve already deployed optical networks is to use higher order modulation formats together with coherent detection and digital signal processing. Phase-based modulation formats can provide sufficient performance improvement by phase noise compensation. First implemented phase noise algorithm exhibits potential improvement in bit error rate more than 6 orders of magnitude for 4-QAM with compared to QPSK and DQPSK. The second algorithm significantly achieves improvement in bit error rate but has comparable results in compensating for phase noise according to the number of symbols in constellation diagram.