Abstract
The superiority of optical communications in underwater mediums, in terms of higher data rate and reliability, makes underwater optical wireless communications (UOWC) more favorable to provide ultra-reliable low-latency underwater communications, as compared to other wireless technologies, e.g., acoustic and radio frequency (RF) communications. UOWC limited transmission range, however, remains a major hurdle against assessing its true deployment benefits, which motivates for the necessity of developing practical routing protocols for multi-hop underwater optical wireless sensor networks (UOWSNs). This work sheds light on the existing state-of-art UOWC routing protocols, the majority of which requires centralized implementation with large end-to-end delay. The article further proposes routing algorithms which can be implemented in a distributed fashion across the multi-hop links, with a reasonable amount of information exchange. The merits of the proposed algorithms are particularly highlighted through illustrative simulations, which show how the proposed strategies outperform the classical protocols, both in terms of reliability and end-to-end latency. Finally, this work shows how the proposed distributive routing protocols achieve ultra-reliable low-latency underwater communications.
The rapid growing human activities underwater require the utilization of various underwater networks. In order to meet such demands an underwater wireless communication technology with high data rate and transmission speed becomes essential
Since UOWC supports high data rate and low latency communication, it becomes a strong candidate to realize ultra-reilble low-latency underwater communication . To do so, an UOWSNs must
- maintain the network communication reliability between [ 1-10^{-6} - 1-10^{-9}].
- achieve an end-to-end (E2E) latency in the order of ms.
This work, therefore, focuses on:
- Examining the characteristics of UOWC in the line-of-sight (LoS) condition with different types of seawater and different beam-widths of the optical signal.
- Investigating centralized routing protocols , and proposing new distributed routing protocols.
- Evaluating each protocol in terms of the design parameters of URLLUC, i.e., end-to-end bit error rate (BER) and end-to-end time delay.
This work is one step forward towards realizing ultra-reliable low-latency underwater optical communication, by means of efficient routing in underwater optical wireless sensor networks. This work proposes new routing algorithms which can be implemented in a distributed fashion across UOWSNs. Numerical results validate the performance and qualification of the proposed routing protocols towards achieving ultra-reliable low-latency underwater optical communication. The proposed distributed sector-based and sweeping-and-sector-based routing protocols exhibit a trade-off in the superiority of their performance to realize URLLUC in the presence of absorption, scattering, and geometrical losses. Finally, this work elucidates the drawbacks of utilizing a centralized routing protocol in UOWSNs.