LocalVLC: Augmenting Smart IoT Services with Practical Visible Light Communication
2019 IEEE 20th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM)
case for smart homes changing the light color to indicate a successful user authorization. However, in spite of those distinct advantages, many VLC designs focus mainly on the communication performance and novel functionality -  . This results in a dilemma for deploying VLC in practice because existing solutions either entail high energy overhead or exhibit unpleasant visual experiences due to the perceptible light flickering effects for end users  . The light flickering effect
... kering effect greatly limits the deployment and applicable scenarios of VLC (e.g., to be used as a regular light source for indoor). In light of this challenge, the DarkLight design  tackles the problem sphere by emitting extremely-low luminance of light pulses, which makes the lighting device appear as a unnoticeable "dark" bulb. Although DarkLight addressed the flickering issue through an unconventional design, their solution provides a shorter communication range (1.3 m) and cannot replace existing regular light sources compared to our custom light bulb. Specifically, a dedicated DarkLight bulb should be installed besides normal LED lamps where DarkLight services are needed which causes light pollution by overlapping light signals for illumination and communication. This leads to the fundamental question of adopting VLC: how to achieve a practically deployable VLC with low cost and power footprint? Given that common VLC modulation schemes can hardly keep light pulses imperceptible and hence causing light flickering effects , we tackle the usability challenge for VLC by proposing a holistic system solution named LocalVLC. In its core, LocalVLC introduces a Morsecode inspired modulation scheme that can operate on off-theshelf LEDs with low energy overhead. We have implemented and evaluated a full-fledged system prototype based on Lo-calVLC design. In practical settings, our LocalVLC prototype can support up to 10 meters of range and attain reasonable throughput (up to 1.4 Kbps) with low error rate and energy consumption. Compared to the widely adopted Manchester encoding, LocalVLC yields 8x improvement on both throughput and energy consumption. Our design can effectively overcome the light flickering effect by encoding data into high frequency light pulses but does not require extra processing hardware such as FPGA or micro-controller. As inspired by but different from DarkLight, LocalVLC can be deployed as standard light source to overcome the light pollution problem by replacing existing lighting. The unique features of VLC can benefit many Abstract-Visible Light Communication (VLC) emerges as a communication technology for Internet of Things (IoT) services with appealing benefits n ot p resent i n e xisting r adio-based communication. However, current VLC designs commonly require dedicated LED lights to emit modulated light beams which entail high energy overhead and unpleasant visual experiences due to the perceptible light blinking effects for end users. This greatly limits the deployment and applicable scenarios of VLC. In this paper, we design and develop LocalVLC, a practical and lowcost VLC system that can be used as a standard light source to augment smart IoT services. LocalVLC introduces a novel Morsecode inspired modulation scheme that can operate on off-the-shelf LEDs with low energy overhead. It can effectively overcome the light flickering by encoding data into high frequency light pulses without requiring extra processing hardware such as FPGA or micro-controller. We have implemented and evaluated a fullfledged s ystem p rototype b ased o n L ocalVLC d esign. Under practical settings, our LocalVLC prototype can support up to 10 meters of range, and attain reasonable throughput (up to 1.4 Kbps) with low error rate and energy consumption. Comparing with the widely adopted Manchester encoding, LocalVLC yields 8x improvement on both throughput and energy consumption. In addition, we demonstrate the practicality of LocalVLC through two IoT use cases where we developed two lightweight LocalVLCbased solutions using low-cost off-the-shelf hardware to exemplify the usage of LocalVLC for indoor service discovery and smart home key management.