[Paper Review] Underwater Optical Wireless Communications, Networking, and Localization: A Survey

Nasir Saeed, Abdulkadir Çelik+2 more|arXiv (Cornell University)|Feb 28, 2018

Optical Wireless Communication Technologies282 references4 citations

TL;DR

This survey provides a comprehensive, layer-by-layer analysis of underwater optical wireless communications (UOWC), networking (UOWN), and localization, highlighting challenges like absorption, scattering, and link misalignment, while proposing advanced techniques for high-data-rate, low-latency underwater communication. It identifies key research gaps in practical implementations, energy harvesting, hybrid systems, and localization, and advocates for cross-layer design and IoUT integration to enable future smart underwater networks.

ABSTRACT

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Motivation & Objective

• To address the limitations of acoustic and RF-based underwater communications, which suffer from low bandwidth and high latency.
• To explore the potential of optical waves—particularly in the 450–550 nm band—for high-speed, low-latency underwater communication.
• To identify and analyze key challenges in UOWNs across all protocol layers, including physical layer impairments, link budget constraints, and network scalability.
• To examine the role of localization in enabling location-aware networking, tracking, and data tagging in underwater environments.
• To highlight open research challenges in energy harvesting, hybrid acoustic-optical systems, and the development of the Internet of Underwater Things (IoUTs).

Proposed method

• Conduct a systematic, layer-by-layer survey of UOWNs, covering physical, data link, network, transport, and application layers.
• Analyze propagation characteristics and channel modeling for underwater optical waves, emphasizing wavelength-dependent attenuation (especially 450–550 nm for blue-green light).
• Review modulation techniques, link budget calculations, multiple access schemes, and performance metrics such as BER and spectral efficiency.
• Survey relaying techniques, routing algorithms (e.g., location-based, energy-aware), and congestion control mechanisms for multi-hop UOWNs.
• Examine localization techniques tailored for UOWC, including pointing, acquisition, and tracking (PAT) challenges, and their integration with networking layers.
• Propose cross-layer design principles that jointly optimize connectivity, energy efficiency, and localization accuracy across UOWN layers.

Experimental results

Research questions

• RQ1 What are the key physical layer impairments affecting underwater optical wireless communication, and how do they limit transmission range and data rate?
• RQ2 How can cross-layer design principles improve the performance of underwater optical wireless networks across multiple protocol layers?
• RQ3 What are the most effective localization techniques for underwater optical sensor nodes, and how do they integrate with routing and clustering in UOWNs?
• RQ4 What are the major challenges in developing practical, energy-efficient, and scalable UOWNs, and how can hybrid acoustic-optical systems mitigate these issues?
• RQ5 How can energy harvesting from underwater ambient sources (e.g., acoustic, microbial) extend the lifetime of underwater optical sensor networks?

Key findings

• Optical waves in the 450–550 nm range (blue-green light) exhibit the lowest attenuation in seawater, making them ideal for high-speed underwater optical communication.
• LED-based UOWC systems face bandwidth limitations, restricting achievable data rates despite advances in modulation and signal processing.
• Underwater optical channels suffer from severe scattering, turbulence, and beam misalignment, significantly degrading link quality and range.
• Current UOWN implementations are limited by low transmission range, high energy consumption, and lack of robust transceivers, necessitating further hardware development.
• Energy harvesting from acoustic waves and microbial fuel cells shows promise but remains underdeveloped for underwater optical networks.
• Hybrid acoustic-optical systems and multi-hop UOWNs are emerging as viable solutions for extending coverage and enabling the Internet of Underwater Things (IoUTs).