Recent Advances in the Hardware of Visible Light Communication

Abstract

Visible light communication (VLC) is an emerging technology that can transform lighting facilities into access points for wireless communication. Its development is bottlenecked by the cut-off frequencies (e.g.,-6-dB electrical cut-off frequency fc and-3-dB electrical cut-off frequency f-3dB) of hardware, such as light-emitting diodes (LEDs), color converters, and photodetectors (PDs). In the past decade, especially in 2018, many materials and devices have been tested for properties related to VLC, such as fc, response time, and transmission data rates, which are listed and analyzed here to get an updated overall picture. The f-3 dB for the latest blue LED and color converter can reach up to 1485 and 470 MHz, respectively, which are great improvements from < 5 MHz for conventional white LEDs. Among the new PDs, the largest characterized fc is 4.2 MHz. Moreover, the smallest response time of these PDs is 0.95 ns, which is promising to have fc of hundreds of megahertz. The limitation in the field of view when the active area is reduced to enlarge fc of the PD can be partially overcome with novel fluorescent antenna, whose fc is more than 40 MHz. These increments in the fc or f-3dB of hardware not only enlarge the channel capacity of the VLC but also facilitate the channel impulse response measurement, and the system becomes more susceptible to changes in the environment. These advances will shed light on the future development of the VLC with faster speed, more portable devices, and more applications for the Internet of Things.