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A Comparative Survey of Optical Wireless Technologies: Architectures and Applications
Mostafa Zaman Chowdhury, Md. Tanvir Hossan, Amirul Islam, Yeong Min Jang
TL;DR
5G and beyond face rapidly increasing wireless-capacity demands that regulated RF spectrum cannot fulfill. This survey reviews OWC technologies, compares their architectures and applications, and identifies their roles in high-capacity connectivity.
Problem
Regulated RF spectrum cannot fulfill the rapidly increasing wireless-capacity demands of 5G and beyond communications.
Method
The paper surveys VLC, LiFi, OCC, FSOC, and LiDAR across classification, spectrum use, architecture, applications, and comparisons with RF technologies.
Results
The review clarifies differences among OWC technologies and identifies applications including small-cell hotspots, high-capacity backhaul, and hybrid RF-optical networks.
Takeaways & Limitations
OWC can support high-data-rate 5G and massive IoT connectivity through optical-spectrum use, including indoor, outdoor, and long-distance applications.
Abstract
from arXiv · showhide
New high-data-rate multimedia services and applications are evolving continuously and exponentially increasing the demand for wireless capacity of fifth-generation (5G) and beyond. The existing radio frequency (RF) communication spectrum is insufficient to meet the demands of future high-datarate 5G services. Optical wireless communication (OWC), which uses an ultra-wide range of unregulated spectrum, has emerged as a promising solution to overcome the RF spectrum crisis. It has attracted growing research interest worldwide in the last decade for indoor and outdoor applications. OWC offloads huge data traffic applications from RF networks. A 100 Gb/s data rate has already been demonstrated through OWC. It offers services indoors as well as outdoors, and communication distances range from several nm to more than 10000 km. This paper provides a technology overview and a review on optical wireless technologies, such as visible light communication, light fidelity, optical camera communication, free space optical communication, and light detection and ranging. We survey the key technologies for understanding OWC and present state-of-the-art criteria in aspects, such as classification, spectrum use, architecture, and applications. The key contribution of this paper is to clarify the differences among different promising optical wireless technologies and between these technologies and their corresponding similar existing RF technologies
I. INTRODUCTION
The paper surveys optical wireless communication as a complement to RF for 5G and IoT, comparing technologies, architectures, spectra, and application scenarios. It emphasizes OWC's broad range and capacity while noting technology-specific limitations and the value of hybrid networks.
- Motivation: 5G and IoT require substantially higher capacity, connectivity, and performance than existing wireless networks can provide.The paper cites 1000-fold higher mobile data volume per area and 100-fold more connected devices for 5G.
- Integration with RF: OWC can complement RF to relieve spectrum shortage, but optical links remain sensitive to obstacles and limited transmitted power.The paper therefore identifies coexistence and hybrid networks as practical approaches for future communications.
- OWC scope: OWC uses visible, infrared, and ultraviolet optical bands to provide wireless connectivity across indoor and outdoor environments.The surveyed technologies include VLC, LiFi, OCC, FSOC, and LiDAR.
- Applications: OWC spans applications from chip-to-chip and device-to-device links to transportation, healthcare, underwater communication, and space.The applicable communication forms include D2D, M2M, V2X, point-to-point, and multipoint links.
- 5G and IoT: VLC, LiFi, and OCC support dense small-cell hotspots, while FSO, LiFi, and VLC can provide high-capacity backhaul for 5G and beyond.The paper also describes OWC as low-power, secure, and suitable for diverse indoor and outdoor devices.
- Survey contribution: The survey compares OWC technologies by optical sub-band, transmitters and receivers, architecture, operating principles, communication scenarios, and applications.The comparison includes range, data rate, reliability, LOS/NLOS operation, indoor/outdoor use, and functions such as illumination, localization, imaging, and mapping.
II. OVERVIEW
The overview classifies OWC by optical spectrum and communication distance. It presents optical communication as spanning extremely short inter-chip links through ultra-long-range inter-satellite connections.
- Spectrum classification: The optical spectrum provides a large complement to regulated RF, with infrared, visible, and ultraviolet bands offering distinct communication properties.The paper highlights IM/DD as a relatively straightforward implementation enabled by widely available incoherent front-end components.
- Distance classification: OWC systems are classified by distance into ultra-short, short, medium, long, and ultra-long ranges.These categories organize applications according to communication distance and medium.
- Range-based applications: OWC applications extend from nm/mm-level chip-to-chip communication through WBAN, WPAN, underwater, VLC-based WLAN, outdoor V2X, and inter-building links.The overview associates these examples with progressively larger communication ranges.
- Ultra-long range: Ultra-long-range OWC includes inter-satellite, satellite-earth, satellite-airplane, airplane-satellite, airplane-airplane, and airplane-ground links.These links demonstrate the use of OWC across space and air-to-ground communication scenarios.
- Overview: The classification covers communication networks from ultra-short-range inter-chip links to ultra-long-range inter-satellite communications.The paper presents this range diversity through its transmission-range figures.
B. Infrared vs VL vs Ultraviolet for OWC
OWC spans infrared, visible-light, and ultraviolet bands, supporting technologies and applications across diverse transmission ranges. Band choice affects communication direction, range, data rate, and transmitter constraints.
- Spectrum use: The visible-light spectrum is widely used by VLC, LiFi, and OCC, while near-infrared supports FSO, OCC, LiFi, and LiDAR.
- Ultraviolet: Ultraviolet communication supports high-speed line-of-sight and non-line-of-sight links, including NLOS operation through directed omnidirectional transmission.
- NLOS communication: Infrared and visible-light reflections can provide low-data-rate NLOS communication, whereas ultraviolet supports high-data-rate NLOS communication.
- Transmitters: LEDs combine illumination with communication through rapid intensity switching, but incoherence lowers optical power and ambient light causes interference.
- Transmitters: Laser diodes provide directed, long-distance, high-data-rate links with less interference, but their low aperture restricts communication to point-to-point operation.
III. ENABLING TECHNOLOGIES
OWC enabling technologies combine optical transmitters, photodetector or camera receivers, and optical-band media into architectures supporting diverse networks and applications. VLC particularly integrates communication with illumination, localization, and connectivity services.
- Architectures: OWC architectures differ in modulation, transmitters, receivers, and communication media across VLC, OCC, LiFi, FSO, and LiDAR.
- Architectures: Optical systems use LEDs or LDs as transmitters, PDs or cameras as receivers, and infrared, visible, or ultraviolet spectra as media.
- Applications: VLC supports communication, illumination, localization, and high-speed connectivity across homes, offices, vehicles, aircraft, trains, and roadsides.
- Capabilities and limits: VLC offers 10,000 times more bandwidth capacity than RF-based technologies but remains limited outdoors and over long distances.
- Applications: VLC applications include vehicle links, hospitals, aviation, underwater communication, smart signage, location services, local networks, and sound transmission.
- VLC architecture: VLC access networks connect LED, LD, camera, image-sensor, or photodetector endpoints to the Internet or core network through wired or wireless backhaul.
B. Light Fidelity (LiFi)
LiFi is a bidirectional optical wireless technology that complements WiFi by using optical spectrum and supporting mobility. It offers high demonstrated speeds and security advantages but remains constrained outdoors and over long ranges.
- Definition and differences: LiFi uses visible light in the forward path and may use infrared, visible, or ultraviolet light in the return path, unlike VLC’s visible-light-only medium.
- Definition and differences: LiFi must provide seamless user mobility, whereas VLC systems may be unidirectional or bidirectional without the same mobility requirement.
- Performance: 56 Gbps was achieved using a vertical-cavity surface-emitting laser, while a single microLED demonstrated speeds over 3 Gbps.
- Advantages: LiFi’s potential advantages over WiFi include very fast data rates, lower cost, available spectrum capacity, and better security.
- Applications and limits: LiFi is promising for electromagnetic-sensitive areas such as hospitals, nuclear plants, and aircraft cabins, but is ineffective outdoors and for long-range communication.
C. Optical Camera Communication (OCC)
OCC uses cameras or image sensors to communicate through optical images, enabling positioning, monitoring, and vehicle-related applications. Its spatial resolution and distance stability are balanced by line-of-sight and camera-frame-rate limitations.
- Operating principle: OCC differs from VLC because it can use infrared or visible light, only LEDs as transmitters, and cameras or image sensors as receivers.
- Operating principle: OCC uses a camera or image sensor as a receiver, projecting light from different directions onto separate pixels for spatially resolved sampling.
- Performance: Received optical signal power remains stable with changing distance as long as the imaged LED remains at least one pixel in size.
- Limitations: Conventional cameras commonly operate at 30 fps, limiting OCC data rates because each pixel’s rate must satisfy the Nyquist requirement.
- Applications: OCC supports simultaneous monitoring and data communication for autonomous vehicles, plus high-accuracy indoor positioning using uniquely identified LEDs.
- Applications: OCC enables digital-signage communication, drone-to-drone links, augmented or virtual reality services, and cm-level indoor and outdoor localization.
D. Free Space Optical Communication (FSOC)
FSOC uses focused laser beams, typically in the NIR spectrum, to provide high-data-rate links between fixed points over distances from a few nm to several thousand kilometers. Its broad applications and bandwidth are balanced by reliability challenges caused by atmospheric conditions and obstructions.
- Architecture and operation: FSOC typically uses NIR light, although VL and UV spectra are also possible, and does not require illumination.Laser diodes and narrow focused beams support high-data-rate communication between fixed points.
- Architecture and operation: FSOC supports links ranging from a few nm to several thousand kilometers through optical beamforming.The transmitter encodes and modulates data, optionally amplifies the beam, and sends it toward a distant receiver.
- Performance and applications: 40 Gbps FSO links have been implemented over 20 m, while recent FSOC data rates are comparable to fiber-optic systems.The technology also offers very high available bandwidth because its frequency exceeds 300 GHz and is globally unregulated.
- Performance and applications: FSOC applications include cellular backhaul, disaster recovery, high-definition television, medical transmission, surveillance, satellite connectivity, and fiber backup.The surveyed scenarios also include building-to-building, ship-to-ship, underwater, and inter-satellite links.
- Limitations: FSOC reliability is limited by weather, atmospheric turbulence, and physical obstructions, which can increase attenuation or disrupt links.These effects are especially important in long-range communications.
E. Light Detection and Ranging (LiDAR)
LiDAR is an optical remote-sensing technology that uses laser-scattered light to measure distant targets and construct high-resolution spatial representations. It supports airborne mapping, autonomous-vehicle perception, and applications across transportation, science, engineering, and exploration.
- Technology and components: LiDAR uses NIR and VL laser light to determine target range or other target information across materials including aerosols, clouds, dust, and non-metallic objects.Its narrow beam can map physical features at high resolution.
- Technology and components: A LiDAR system comprises a laser, photodetector and receiver electronics, scanner and optics, and position and navigation subsystems.Laser beams measure scattered-light properties and generate points for 3D mapping.
- Platforms and operation: Airborne LiDAR collects terrain data by scanning the ground, determining aircraft position and altitude with GPS, and tracking aircraft tilt with an inertial measurement unit.Airplane, ground, and space platforms are used to collect LiDAR data.
- Applications: Autonomous vehicles combine LiDAR distance measurements with radar information to build 3D environmental images and support steering, braking, and acceleration decisions.The cited vehicle example contrasts a real scene with its LiDAR-generated 3D map.
- Applications: LiDAR applications span meteorology, transportation, archaeology, forestry, geology, military systems, robotics, astronomy, and space exploration.Reported uses include obstacle detection, terrain mapping, vegetation measurement, and lunar-distance measurement with mm precision.
A. Summary
The survey compares OWC technologies by spectrum, architecture, transmitters, receivers, capabilities, and application settings. It concludes that VLC, LiFi, OCC, FSO, and RF offer distinct trade-offs in range, data rate, interference, mobility, and use cases.
- Technology comparison: VLC supports illumination, communication, and localization, whereas LiFi supports illumination and communication with bidirectional mobility-oriented operation.Both provide high data rates but are less effective outdoors because of natural-light interference and limited distance.
- Technology comparison: OCC supports communication, imaging, and positioning, while FSO provides long-distance optical links and RF supports radio-based communication.The comparison distinguishes technologies by operating principles, architectures, and application scenarios.
- System characteristics: 100 Gbps has been achieved using LD in OWC, while the comparison lists 10 Gbps using LED, 54 Mbps for OCC, and 40 Gbps for FSO.These values are reported as technology comparison entries with different transmitters and systems.
- System characteristics: OWC technologies use VL, IR, or UV spectra with LED or LD transmitters and PD or camera receivers, unlike RF systems using antennas.The surveyed systems differ in receiver type, modulation options, interference, path loss, and illumination capability.
- Limitations and range: VLC is identified as short-distance, without guaranteed mobility support, and unsuitable for outdoor use in the comparison.The table also lists communication distances of 20 m for VLC, 200 m for OCC, and more than 10000 km for FSO.
B. Open Issues and Future Research Directions
The survey identifies open issues spanning spectrum extension, underwater and vehicular links, mobility, atmospheric loss, MIMO, hybrid networking, interference, and human-compatible operation. These directions target higher capacity, reliability, coverage, positioning, and practical deployment of OWC systems.
- Network architectures: Hybrid networks such as WiFi/LiFi, VLC/FSO, and LiFi/OCC can combine technologies to improve load balancing, link reliability, availability, and interference reduction.Adaptive and smooth switching between communication systems remains a major challenge.
- Capacity and coverage: OWC research targets high-capacity optical backhaul, NLOS UV communication, and underwater links requiring long-range and high-speed operation.The paper also identifies spectrum extension beyond UV as a challenging future direction.
- Deployment challenges: Dense VLC/LiFi deployments face inter-cell optical interference, and OCC data rates remain limited at 55 Mbps in the cited discussion.RGB-LED OCC and improved dimming algorithms are proposed research directions.
- Mobility: Seamless mobility requires horizontal and vertical handovers, while the survey states that currently only LiFi provides seamless connectivity.Handover mechanisms are needed to maintain communication across LiFi and hybrid LiFi–WiFi networks.
- MIMO and reliability: MIMO remains challenging in OWC because of IM/DD channel properties, receiver-angle limitations, complexity, and sensitivity to transmitter–receiver misalignment.Researchers are investigating accurate channel models and MIMO applicability across OWC technologies.
- Deployment challenges: LED modulation must avoid flicker because brightness fluctuations can harm human health and impede OWC deployment.Flicker avoidance is presented as an important research issue.
V. CONCLUSIONS
OWC is presented as a complementary solution to RF capacity shortages, spanning multiple technologies, distances, and application domains. The survey emphasizes that each technology has distinct advantages, limitations, and appropriate applications.
- OWC can complement RF networks to address the exponential growth in wireless-capacity demand for 5G and beyond.
- The survey covers VLC, LiFi, OCC, FSOC, and LiDAR as the main optical wireless technologies.
- These technologies support communication from ultra-short to ultra-long distances.
- OWC technologies have distinct advantages and limitations, so their application areas differ.
- Potential application domains include industry, healthcare, public venues, transportation, residences, offices, shopping malls, underwater communication, and space.