Performance Analysis of Two-Hop Active Relaying for Dynamic Magnetic Induction Based Underwater Wireless Sensor Networks.

In this paper, we investigate the two-hop active relaying for dynamic magnetic induction based underwater wireless sensor networks (MI-UWSNs). Specifically, we firstly propose the two-hop active relaying schemes with unidirectional (UD) and tri-directional (TD) active relays, respectively, by considering the angular misalignment in practical underwater MI environments. Then, the statistical properties of the received signal-to-noise ratio (SNR) for the proposed two-hop UD and TD active relaying schemes are rigorously analyzed and the corresponding closed-form expressions of the probability density functions are derived according to the distribution of the angular misalignment. Based on the statistical SNRs, we develop the analytical expressions of the ergodic achievable rate and the average bit-to-error rate for the two-hop UD and TD active relaying schemes employing the amplify-and-forward and decode-and-forward strategies. Extensive simulation results validate the effectiveness of our theoretical analyses and demonstrate that the proposed two-hop TD active relaying scheme performs the best among all comparative schemes.