End-to-End Performance Analysis of Underwater Optical Wireless Relaying and Routing Techniques Under Location Uncertainty

Abstract

On the contrary of low speed and high delay acoustic systems, underwater optical wireless communication (UOWC) can deliver a high speed and low latency service at the expense of short communication ranges. Therefore, multihop communication is of utmost importance to improve degree of connectivity and overall performance of underwater optical wireless networks (UOWNs). In this regard, this paper investigates relaying and routing techniques and provides their end-to-end (E2E) performance analysis under the location uncertainty. To achieve robust and reliable links, we first consider adaptive beamwidths and derive the divergence angles under the absence and presence of a pointing-acquisitioning-and-tracking (PAT) mechanism. Thereafter, important E2E performance metrics (e.g., data rate, bit error rate, transmission power, amplifier gain, etc.) are obtained for two potential relaying techniques; decode & forward (DF) and optical amplify & forward (AF). We develop centralized routing schemes for both relaying techniques to optimize E2E rate, bit error rate, and power consumption. Alternatively, a distributed routing protocol, namely Light Path Routing (LiPaR), is proposed by leveraging the range-beamwidth tradeoff of UOWCs. LiPaR is especially shown to be favorable when there is no PAT mechanism and available network information. In order to show the benefits of multihop communications, extensive simulations are conducted to compare different routing and relaying schemes under different network parameters and underwater environments.

Relay-Assisted Technology in Optical Wireless Communications: A Survey

“…In UOWC, the optical signal received at each hop is converted into an electrical signal, which is then decoded, encoded, and transmitted to the next hop in DF transmission [185]. Although DF greatly improves electrical-to-electrical performance by limiting background noise propagation, it introduces additional power consumption and signal processing delays.…”

“…For latter, after it received the light signal, and then converted it to electrical signal, next to decoded, eventually re-encoded and forward to the next hop. Thus, DF relaying needs converter, decoder, and encoder with high-speed data to achieve data rates for Gbps [185].…”

Investigation of the Scattering Noise in Underwater Optical Wireless Communications

“…Whereas the latter is due to photons propagating direction, which is changing randomly because of (i) interaction with the water particles with sizes comparable to the carrier wavelength (i.e., diffraction); and/or (ii) changing refractive indices (i.e., refraction). In turbid waters, especially coastal and harbor, the transmitted photons will experience multiple scattering [11,12]. In [13], it is shown that the multiple scattering and system geometries affected the temporal dispersion.…”

Efficient coverage greedy packet stateless routing in wireless sensor networks

“…ERA-based protocols are of great importance, as energy is conscious or residual energy is increasing uniformly across the network, and find the right pathways and long network lives. 2–7…”