Joint Visible Light and RF Backscatter Communications for Ambient IoT Network: Fundamentals, Applications, and Opportunities

TL;DR

A joint VLC-AmBC architecture is proposed, emphasizing fundamental concepts, system designs, and practical implementations, thereby providing a clear roadmap for future developments in joint VLC-AmBC-enabled A-IoT ecosystems.

Abstract

The rapid growth of the Internet of Things (IoT) devices in the sixth-generation (6G) wireless networks raises significant generality and scalability challenges due to energy consumption, deployment complexity, and environmental impact. Ambient IoT (A-IoT), leveraging ambient energy harvesting (EH) for batteryless device operation, has emerged as a promising solution to address these challenges.Among various EH and communication techniques, visible light communication (VLC) integrated with ambient backscatter communication (AmBC) offers remarkable advantages, including energy neutrality, high reliability, and enhanced security. In this paper, we propose a joint VLC-AmBC architecture, emphasizing fundamental concepts, system designs, and practical implementations. We explore potential applications in environmental monitoring, healthcare, smart logistics, and secure communications. We present proof-of-concept demonstrations for three distinct types of ambient backscatter devices (AmBDs): EH-Only, VLC-Relay, and VLC-Control. Experimental results demonstrate the feasibility of implementing joint VLC-AmBC systems, highlighting their practical viability across various deployment scenarios. Finally, we outline future research directions, including integrated sensing and communication, as well as optimized energy-efficient deployment. Open issues, such as large-scale deployment challenges, are also discussed, thereby providing a clear roadmap for future developments in joint VLC-AmBC-enabled A-IoT ecosystems.

Figures (5)

• Figure 1: Joint VLC-AmBC system architecture with three types of AmBDs: (a) EH-Only AmBD harvests optical energy from LED APs solely for powering the device. (b) VLC-Relay AmBD exploits VLC signals not only for EH, but also for relaying messages from VLC APs to RF receivers. (c) VLC-Control AmBD uses VLC signals for EH and for controlling various operational states of the device, such as waking up, data collection, and backscattering. All AmBDs modulate and backscatter ambient RF carriers from AmRFSs. The backscattered signal can be received and decoded by general-purpose RF receivers.
• Figure 2: Applications of the proposed system: Environmental monitoring, healthcare, logistics and transportation, and secure communications.
• Figure 3: Three PoC prototypes (left) for EH-Only, VLC-Relay and VLC-Control AmBDs, respectively, where a 2-euro coin is placed to showcase their scale. In the setup (right), VLC link distances $d_{\textrm{LED-BD}}$ and BC link distances $d_{\textrm{RX-BD}}$ are systematically varied during experiments using the control variates method.
• Figure 4: Experimental results for the three AmBDs. (a) BER vs. SNR, compared with the theoretical performance of a non-coherent BFSK system. (b) BER across varying VLC link distances. (c) BER across varying BC link distances. (d) RSS across varying BC link distances, compared with the theoretical link budget griffin2009linkbudget.
• Figure 5: Normalized sensitivity of (a) BER, and (b) RSS, in terms of the distance changes in the VLC link and BC link per centimeter.