Single cell multiple-channel VLC with 3-level amplitude-based CDMA

In this paper, we present a practical multi-channel transmission system with visible light communication (VLC) for electromagnetic-wave-free indoor healthcare service. Code division multiple access (CDMA) was employed for the transfer of multiple medical datasets in real-time with a simple system design. Multi-user datasets were spread to time-domain chips using an orthogonal codebook, and simultaneously transmitted using a single light-emitting diode (LED). The LED device transmits an energy-normalized chip signal based on only three different voltage levels, with the light source going into an optical detector. The received signal, which includes code-division multiplexed data, is separated by an orthogonal code and concurrently rearranged for transmission to a user interface (PC or mobile). The obtained multiple datasets were monitored in real-time and analyzed for appropriate medical services.