High-Speed Single Channel 16-QAM-OFDM UOWC System: Performance Evaluation for Various Types of Waters

The expansion of marine engineering requires exploring high data transmission in underwater (UW) environments. In this paper, a high-speed underwater optical wireless communication (UOWC) system employing orthogonal frequency division multiplexing (OFDM) with 16-quadrature amplitude modulation (QAM) to address the need for high data transmission in underwater (UW) environments is proposed. Utilizing a single laser diode (LD) source operating at a wavelength of 532 nm, chosen for its lower attenuation in UW conditions, the system employs carrier phase estimation to compensate for phase errors at the receiver. The performance of the system is evaluated across ten different types of waterbodies, considering metrics such as bit error rate (BER), UW range, error vector magnitude (EVM), received optical power (ROP), and constellation diagrams. Results indicate a transmission range of 11.75 m in pure sea (PS) and 11 m in Jerlov type I (JI) waters, with the lowest absorption and scattering coefficients. Conversely, the model achieves a 2.85 m range in harbor type II (HII) water, exhibiting the highest attenuation. At these ranges, ROP and EVM% measure approximately -28.7 dBm and 16%, respectively, with all values obtained at a BER below 3.8×10 −3 , which falls below the limit for hard-decision forward error correction.