Pixelated VLC-Backscattering for Self-Charging Indoor IoT Devices

Visible light communication (VLC) backscatter has been proposed as a wireless access option for Internet of Things. However, the throughput of the state-of-the-art VLC backscatter is limited by simple single-carrier pulsed modulation scheme, such as ON-OFF keying (OOK). In this letter, a novel pixelated VLC backscatter is proposed and implemented to overcome the channel capacity limitation. In particular, multiple smaller VLC backscatters are integrated to generate multi-level signals, which enables the usage of advanced modulation schemes. Based on experimental results, rate adaptation at different communication distances can be employed to enhance the achievable data rate. Compared with OOK, the data rate can be tripled, when 8-pulse amplitude modulation is used at 2 m. In general, n-fold throughput enhancement is realized by utilizing n smaller VLC backscatters, while incurring negligible additional energy using the same device space as that of a single large backscatter.