Why Visible Light Positioning is the Future of Indoor Drone Navigation

The Challenge of the indoor positioning system

To push toward fully autonomous smart factories, drones and mobile robots are becoming indispensable. However, indoor autonomous navigation still faces a massive barrier: GPS signals are blocked by roofs and walls, making them unsuitable for indoor navigation. While traditional radio-frequency (RF) solutions like Wi-Fi or Bluetooth can be used indoors, they generally suffer from multipath interference and signal instability, usually achieving only meter-level accuracy. Moreover, balancing infrastructure deployment costs remains challenging for high-precision positioning systems, such as those utilizing Ultra-Wideband (UWB) sensors [1].

Lighting Up with VLP

This is where Visible Light Positioning (VLP) comes in. VLP leverages ubiquitous and economical Light-Emitting Diodes (LEDs) that are already installed for daily illumination.

By modulating the LED light, we can make the bulbs flicker at high speeds undetectable to the human eye. This allows us to turn existing lighting infrastructure into a network of optical transmitters.

This dual-use of infrastructure perfectly encapsulates the vision of Integrated Sensing and Communication (ISAC). Instead of deploying entirely separate systems for illumination, data transmission, and sensing, ISAC combines them into a unified visible light frequency system. Drones equipped with simple, low-cost photodiodes or off-the-shelf cameras can capture these signals to determine their exact location. Furthermore, because visible light is less subject to the multipath interference that affects RF signals, VLC-based systems can achieve localization accuracy to within 10 cm in controlled environments. [2]

Figure 1: Comparison of VLP performance between a standard parallel receiver and a tilted receiver.

The 6-DoF Complexity for Mobile Drones

While VLP sounds straightforward, moving from static tracking to flying robots introduces severe dynamic challenges. Most early state-of-the-art VLP research assumed the receiver was a static object or moved only in 2D. Drones, however, operate in three-dimensional space with six degrees of freedom (6-DoF).

Whenever a drone moves forward or backward, it must tilt (pitch or roll). This transitional movement constantly changes the incidence angle at which the light hits the light sensors, drastically impacting the received signal strength and degrading location estimation precision.

To solve this, researchers are moving away from relying solely on light. Modern approaches utilize “tightly coupled” integration, fusing VLP data with the drone’s onboard IMU data.

By fusing more data, these advanced tightly coupled systems can account for varying photodiode inclinations and maintain stability even during conditions of severe signal blockage. [3]

Figure 2: The infrastructure challenge: traditional VLP requires multiple overlapping emitters for trilateration (left), whereas sparse environments with a single light source (right) limit the system’s applicability.

The Trade-off: Dense Infrastructure vs. Smart Algorithms

A central challenge in designing VLP systems is the density of the infrastructure. Traditional VLP relies heavily on multi-light-source layouts that require the drone to clearly see multiple different LEDs simultaneously to calculate its position.

If fewer LEDs are in the field of view, such as in corridors or factories with large spacing, the system may be unable to receive signals from multiple light sources simultaneously, limiting its applicability.

However, requiring a dense, perfectly assembled grid of LEDs limits operational flexibility. Consequently, a major research frontier is single-beacon navigation. By shifting the complexity to the drone’s onboard algorithms, achieving centimeter-level positioning without the need for an overlapping canopy of lights has become a critical, yet largely unsolved, objective.

Why This Matters for 6G and JCAS

As we evolve toward 6G, mobile networks are expected to gain the ability to proactively perceive their physical environments, turning the network into a sensory system. VLP demonstrates exactly how we can repurpose everyday infrastructure to solve complex robotic challenges. By utilizing optical signals to satisfy the requirements of both communication capacity and high sensing accuracy, visible light positioning offers a scalable, electromagnetically safe, and highly cost-efficient solution for the future indoor robotic application.

 

References

[1] L. Mainetti, L. Patrono and I. Sergi, A survey on indoor positioning systems, 2014 22nd International Conference on Software, Telecommunications and Computer Networks (SoftCOM). [2] Zhice Yang, Zeyu Wang, Jiansong Zhang, Chenyu Huang, and Qian Zhang. 2015. Wearables Can Afford: Light-weight Indoor Positioning with Visible Light. In Proceedings of the 13th Annual International Conference on Mobile Systems, Applications, and Services (MobiSys ’15). [3] G. Niu, J. Zhang, S. Guo, M. -O. Pun and C. S. Chen, UAV-Enabled 3D Indoor Positioning and Navigation Based on VLC, ICC 2021 – IEEE International Conference on Communications.

 

An article by Chengwei (Harry) Huang