ABSTRACT
In digital signal processing-based coherent reception systems, the recovery of the carrier phases and hence the frequency are critical to achieve the most sensitive reception with maximum performance in the bit-error rate, or evaluation of the probability of error. This chapter illustrates the performance of the processing algorithms in optical transmission systems, and employs coherent reception techniques over highly dispersive optical transmission lines, especially the multispan optically amplified non-dispersion compensating module long-haul distance. It also illustrates the recovery of the carrier phase for quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation optical transmission systems in constellations of single- or multilevel circular distribution. The chapter describes a detailed design and experimental platform for the delivery of Tbps using Nyquist-QPSK at a symbol rate of 28–32 GSa/s and 10 subcarriers. The formation of Nyquist pulse-shaped QPSK superchannels offers better performance and reduces the complexity in the receiver digital signal processing subsystem structure.
