Performance Evaluation of Mixed RF-UOWC System with Residual Hardware Impairments

In this paper, the outage probability (OP) of a dual-hop radio-frequency-underwater optical wireless communication (RF-UOWC) system is inspected. Precisely, a source (S) transmits the information signal to a relay (R) via an RF link. This latter decodes and regenerates the received signal, and hands it to the underwater destination node (D) through an UOWC channel. The RF and UOWC links are subject to Nakagami-m and mixture Exponential-Generalized Gamma fading, respectively. By considering residual hardware impairments (RHI) at the three nodes, a closed-form expression for the system’s OP is derived in terms of the system and channel parameters. Also, the achievable diversity order is evaluated at high signal-to-noise ratio (SNR) regime. The obtained results show that, at high SNR, the underwater turbulence yields an OP loss of approximately 4dB by comparing UOWC links with 2.4 and 7.1 L/min of air bubbles levels, while the RHI exhibit a maximum loss of 4dB for an RHI coefficient of 0.3 compared to the ideal hardware case. Additionally, the end-to-end SNR exhibits a ceiling value, depending exclusively on the RHI level. Finally, the diversity order of the system is shown to be equal to unity.