Open AccessPerformance of grey‐coded IQM‐based optical modulation formats on high‐speed long‐haul optical communication link
Author(s) -
Kakati Dhiman,
Arya Subhash C.
Publication year - 2019
Publication title -
iet communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.355
H-Index - 62
eISSN - 1751-8636
pISSN - 1751-8628
DOI - 10.1049/iet-com.2019.0205
Subject(s) - quadrature amplitude modulation , qam , phase shift keying , computer science , electronic engineering , bit error rate , telecommunications , channel (broadcasting) , engineering
In this article the performance of grey‐coded advanced optical modulation formats is evaluated on a single‐channel high‐speed long‐haul optical communication link and are compared to the respective differential‐coded modulation formats. Polarisation division multiplexed optical in‐phase quadrature modulator (IQM) structure and homodyne detection scheme are used to realise 100 Gbps quadrature phase‐shift keying (QPSK), 120 Gbps 16‐ary quadrature amplitude modulation (16‐QAM), 360 Gbps 32‐QAM and 480 Gbps 64‐QAM modulation formats. Advanced digital signal processing unit with various pre‐processing and recovery stages such as direct current blocking, normalisation, low‐pass Bessel filter, resampling, quadrature imbalance compensation, chromatic dispersion compensation, non‐linear compensation, timing recovery, adaptive equalisation, down‐sampling, frequency offset estimation, and carrier phase estimation is used at the receiving end to compensate for signal impairments during propagation. Maximum transmission distances of 7200, 1050, 560, and 360 km have been achieved at an acceptable bit error rate for QPSK, 16‐QAM, 32‐QAM, and 64‐QAM, respectively. The grey‐coded systems outperformed the differential‐coded systems regarding optical signal‐to‐noise ratio requirement, receiver sensitivity, and transmission distance.