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Performance analysis of dual-polarization underwater optical wireless communication using PAM-4 signals under different water conditions

MEHTAB SINGH1, KARAMJEET SINGH2, AMIT GROVER2,* , SOMIA A. ABD EL-MOTTALEB3, VISHAL SHARMA2

Affiliation

  1. Department of Electronics and Communication Engineering, Chandigarh University, Mohali-140413, Punjab, India
  2. Department of Electronics and Communication Engineering, Shaheed Bhagat Singh State University, Ferozepur, Punjab, India
  3. Alexandria Higher Institute of Engineering and Technology, Alexandria, Egypt

Abstract

Underwater optical wireless communication (UOWC) enables high-speed data links critical for marine operations. This paper proposes a dual-polarization (DP) UOWC system achieving 100 Gbit/s total rate using two 50 Gbit/s four-level pulse amplitude modulation (PAM-4) users. The design uses 532 nm lasers, polarization combining at the transmitter, and splitting at the receiver for direct detection. Performance analysis spans five water types: pure sea, clear ocean, coastal ocean, Harbor I, and Harbor II. All ranges assume a collimated beam with 1 mrad divergence and a pointing/alignment error of 0.1 mrad between transmitter and receiver. We evaluate logarithmic bit error rate (log(BER)), error vector magnitude (EVM%), and received optical power (ROP, dBm) versus range for 16 cm, 18 cm, and 20 cm receiver apertures. In pure sea, the largest (20 cm) receiver delivers log(BER) −2.71 to −0.89 and EVM 18.03–26.78% up to 45.5 m with ROP = −18.80 dBm. Clear ocean reaches 26.4 m (ROP = −18.22 dBm), coastal ocean reaches 15.5 m (ROP = −18.46 dBm), Harbor I reaches 8.0 m (ROP = −18.50 dBm), and Harbor II reaches 4.95 m (ROP = −19.15 dBm). Only the 20 cm design maintains acceptable log(BER) ≈ −2.42 (Q-factor ≈ 2.80) and EVM <20% at maximum ranges across different conditions. Increasing receiver size improves ROP by a nearly constant ≈3.9 dB across all water types, extending range 20-40% versus the 16 cm case. Eye diagrams show clear PAM-4 separation for optimal setups. These results validate DP-PAM-4 robustness and highlight the 20 cm receiver as essential for reliable multi-Gbit/s UOWC in diverse waters.

Keywords

Underwater optical wireless communication, Dual polarization, PAM-4, Bit error rate, Receiver aperture, Water attenuation.

Citation

MEHTAB SINGH, KARAMJEET SINGH, AMIT GROVER, SOMIA A. ABD EL-MOTTALEB, VISHAL SHARMA, Performance analysis of dual-polarization underwater optical wireless communication using PAM-4 signals under different water conditions, Optoelectronics and Advanced Materials - Rapid Communications, 20, 9-10, September-October 2026, pp.436-444 (2026).

Submitted at: March 21, 2026

Accepted at: Oct. 5, 2026