Multiple layer Phase Shift Linear Space-time Block Code for High-speed Visible Light Communications

In this letter, we consider intensity modulation/direct detection (IM/DD) channel in the visible light communication (VLC) systems with multiple transmitter phosphor-based white light emitting diodes (LED) and single receiver avalanche photo diode (APD). We proposed a Multiple Layer Phase Shift Linear Space-time Block Code (MLPS-LSTBC). We show that our proposed code for VLC has the following main features: (a) The symbol transmission rate is $N/(N+M-1)$, where $N$ is the number of transmitter LED and $M$ denotes the number of shift intervals contained by a single codeword per layer; (b) zero-forcing receiver can transform the virtual MIMO matrix channel into parallel sub-channels even without channel state information at the receiver side (CSIR); (c) Our MLPS-LSTBC can asymptotically enhance the spectral efficiency by $\min (M\text{,}N)$, which is attractive for LED-based VLC with limited electrical modulation bandwidth. By simulations, we achieve the record data rate of 1.5 Gb/s with the bit error rate performance below the FEC limit of $2\times10^{-3}$ via multiple 100-MBaud transmission of OOK signal.