WoV: WiFi-based VLC testbed (2001.08489v1)

Abstract: We present a complete Visible Light Communications (VLC) transceiver system consisting of low-cost Commercial-Off-The-Shelf (COTS) components. In particular, we show that COTS IEEE 802.11n (WiFi) devices can be used so that the physical and data link layers of radio frequency (RF) WiFi, i.e. 2.4 GHz, are reused for VLC. Moreover, as WiFi is fully integrated with the Linux system, higher protocols from network to transport and application layer can be used and tested in VLC-related experiments. Our approach has the advantage that a VLC experimenter can fully focus on VLC-related low-level aspects like the design of novel VLC front-ends, e.g. LED drivers, lenses, and photodetectors and test their impact directly on the full network protocol stack in an end-to-end manner with real applications like adaptive video streaming. We present first results from experiments using our prototype showing the performance of unidirectional VLC transmission. Here we analyze the distortions introduced as well as the relationship between signal strength on frame error rate for different MCS and the maximum communication distance. Experimental results reveal that a data rate of up to 150 Mbps is possible over short ranges.

• The paper introduces a novel testbed that repurposes COTS 802.11n WiFi devices to convert RF signals into optical VLC channels.
• It details a methodology using off-the-shelf LED drivers, lenses, and photodetectors to achieve high-speed data transmission with minimal signal loss.
• The study highlights practical implications for cost-effective VLC prototyping and outlines future enhancements for broader indoor and outdoor applications.

Overview of "WoV: WiFi-based VLC Testbed"

The paper "WoV: WiFi-based VLC Testbed" authored by Piotr Gawłowicz, Elnaz Alizadeh Jarchlo, and Anatolij Zubow, presents an innovative approach to leveraging Commercial-Off-The-Shelf (COTS) components to develop a testbed for Visible Light Communications (VLC). Specifically, the paper explores how standard 802.11n (WiFi) devices can be repurposed for optical communication, effectively converting radio frequency (RF) signals into VLC without needing custom-built hardware.

Technical Contributions

The research outlines a VLC transceiver system utilizing COTS components, particularly demonstrating that unmodified WiFi devices can support VLC experiments. The testbed, WoV (WiFi-over-VLC), capitalizes on the existing capabilities of WiFi chipsets, which simplifies the experimenter’s ability to focus on developing and testing novel VLC transceivers. This includes designing front-end components such as LED drivers, lenses, and photodetectors. The approach is underpinned by the ability of WiFi NICs to provide a robust network protocol stack from PHY to application layers, simplifying the end-to-end communication setup in VLC.

The paper details an effective method for down-converting WiFi RF signals (usually in 2.4 GHz or 5 GHz bands) into the optical domain suitable for VLC systems. This conversion is facilitated by RF mixers and local oscillators within the hardware setup, demonstrating that conventional WiFi devices can indeed be retargeted towards VLC applications.

Experimental Results and Findings

Initial experimental results present an interesting perspective on WiFi-based VLC performance:

• Data Transmission Rates: The VLC system can achieve data rates up to 150 Mbps over short distances, reaffirming that the reused infrastructure of WiFi significantly contributes to achieving high-speed VLC.
• Frame Success Rate (FSR) and Signal Strength: Analysis indicates consistent performance characteristics with known wireless communication parameters, such as FSR in relation to the Received Signal Strength Indicator (RSSI). For example, the baseline operating RSSI for certain modulation schemes aligns well with standard WiFi performance metrics.
• Range and Signal Distortion: The conversion and transmission scheme introduces minimal signal distortion, with a noted capability to maintain satisfactory transmission quality over a few meters. The paper also discusses the potential of signal amplification and optical lenses to enhance communication range, although temporal distortions remain a concern with more significant amplification.

Implications and Future Work

The implications of this research are manifold, considering its potential to enable cost-effective prototyping and development of VLC systems on a broader scale. The ability to utilize COTS components allows for easier adoption and experimentation, potentially accelerating the implementation of VLC technologies in real-world environments.

Future developments could address certain limitations noted in the paper, such as bandwidth restrictions. While current results show significant promise for indoor applications, addressing these limitations could enhance the system's capabilities for more complex and broader outdoor environments. Furthermore, as VLC systems continue to evolve, integrating advanced modulation schemes and exploring new use cases within Internet of Things (IoT) frameworks present significant opportunities.

Conclusion

The WoV testbed described in this paper showcases a practical, inexpensive approach to experimental VLC development, bridging existing WiFi technologies with optical communication research. By exploiting the inherent functionalities of WiFi chipsets, the research paves the way for more accessible and extensive VLC experimentation. This work stands as a testament to the potential of repurposing existing communication infrastructure to meet the growing demands of next-generation data communication systems. Such advancements present intriguing prospects for ongoing research into hybrid communication systems and their applications across diverse technological landscapes.