Jaspreet Kaur
Department of Electronics & Communication Engineering, I.K. Gujral Punjab Technical University, Jalandhar, Punjab, India. & Department of Electronics and Electrical Engineering, Sardar Beant Singh State University Gurdaspur, 143521, Punjab, India.

Rakesh Goyal
Department of Electronics & Communication Engineering, I.K. Gujral Punjab Technical University, Jalandhar, Punjab, India.

Gagandeep Kaur
Faculty of Electrical Engineering, Maharaja Ranjit Singh Punjab Technical University, Bathinda, Punjab, India.

DOI https://doi.org/10.33889/IJMEMS.2026.11.5.087

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Abstract

This paper presents a numerical investigation of a 112 Gbps dual‑polarization (DP)-16-quadrature amplitude modulation (QAM) coherent optical fiber link employing a digital signal processing (DSP) chain that includes dispersion and nonlinearity compensation, adaptive equalization, frequency‑offset estimation, and carrier‑phase estimation. First, back‑to‑back performance is compared for 16‑QAM, 32‑QAM, and 64‑QAM using bit error rate (BER) and error vector magnitude (EVM) as functions of optical signal to noise ratio (OSNR), showing that 16‑QAM reaches the forward error correction (FEC) threshold of log(BER) of −2.42 corresponding to a typical soft-decision FEC overhead of about 20% in coherent optical systems with EVM less than 16% at an OSNR of about 17 dB, whereas 32‑QAM and 64‑QAM require approximately 26 dB and 29 dB, respectively. For 80 km single‑mode fiber (SMF) transmission, the proposed DP‑16‑QAM system achieves log(BER) of −4.04 and 12.5% EVM at 20 dB OSNR, indicating only a modest OSNR penalty compared with the back‑to‑back case. Distance‑swept simulations further reveal that, at 20 dB OSNR, log(BER) degrades from −4.82 (back‑to‑back) to −2.08 at 160 km, while EVM increases from 11.0% to 17.9%, still remaining within typical soft‑decision FEC limits. A fixed‑OSNR reach analysis shows that at 18 dB OSNR the link can sustain near‑threshold operation up to about 120 km, whereas at 24 dB OSNR the usable range extends to approximately 170 km before log(BER) rises above −2.42 and EVM exceeds 20%.

Keywords- Coherent optical communication, QAM signals, Digital signal processing, Polarization division multiplexing.

Citation

Kaur, J., Goyal, R., & Kaur, G. (2026). Performance Evaluation of a 112‑Gbps Dual‑Polarization 16‑QAM Coherent Optical Fiber Link with DSP‑Enabled OSNR and Reach Optimization. International Journal of Mathematical, Engineering and Management Sciences, 11(5), 2177-2197. https://doi.org/10.33889/IJMEMS.2026.11.5.087.