# Utilization of an OLED-Based VLC System in Office, Corridor, and Semi-Open Corridor Environments
## 3 Results  
### Comparison of Flat and Curved OLED Based System Performance  
For intensity modulation/direct detection (IM/DD) optical transmission systems, the electrical SNR is defined as  
\[\text{SNR}=\frac{\left(\gamma P_{R}\right)^{2}}{R_{b}N_{o}}=\frac{\left(\gamma H (0)P_{E}\right)^{2}}{R_{b}N_{o}}, \tag{4}\]  
where \(\gamma\) is the photodetector's responsivity in (A/W), \(P_{E}\) and \(P_{R}\) are the emitted and received optical power, respectively, and \(N_{0}\)/2 is double-sided power spectral density. Considering a link with non-return-to-zero (NRZ) on-off keying (OOK), the BER is given as [33]:  
\[\text{BER}=\frac{1}{2}\text{erfc}(\sqrt{\frac{\text{SNR}}{2}}). \tag{5}\]  
Figure 6 shows the plots of the BER for flat and curved OLEDs at \(R_{b}\) of 4 and 6 Mb/s along with the 7% forward error correction (FEC) BER limit of \(3.8\times 10^{-3}\)[1] for an office. Note, for 4 Mb/s the BER is below the FEC limit for curved OLED. As illustrated, the BER plot displays a symmetry about the origin (i.e., at \(\theta\) of \(0^{\circ}\)) because of the same achievable SNR that is maintained across the entire face of OLED. It is obvious that, for the curved OLED the BER is improved over a wider \(\theta\) compared with the flat OLED. Note, for the flat OLED with \(-30^{\circ}<\theta<30^{\circ}\) the BER values are \(<\)\(10^{-6}\). At \(R_{b}\) of  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **Parameter** & & **Value** & \\ \hline \multirow{8}{*}{Surface material refractivity in \% (RGB)} & Chair, sofa (leather) & 24 & 18.8 & 16.3 \\  & Coffee cup (ceramics) & 97.1 & 96.2 & 92.3 \\  & Human clothes (cotton) & 67 & 58 & 45.6 \\  & Plant (leaf) & 14 & 5.9 & 8.2 \\  & Desk, book shelf, book (pine wood) & 70 & 51 & 33.1 \\  & Laptop, PC, printer, and telephone (black gloss paint) & 3.4 & 3.2 & 3.2 \\ \hline Transmission & \multirow{2}{*}{Glass windows} & \multirow{2}{*}{88} & \multirow{2}{*}{90} & \multirow{2}{*}{87} \\ coefficient in \% (RGB) & & & & \\ \hline \multirow{4}{*}{Room size} & Office & \(10\times 10\times 3\) m\({}^{3}\) & \\ \cline{2-4}  & Corridor & \(18\times 40\times 3\) m\({}^{3}\) & \\ \cline{2-4}  & Semi-open corridor & \(26\times 40\times 3\) m\({}^{3}\) & \\ \hline \multirow{8}{*}{Tx} & Dimension & \(1\times 0.5\) m\({}^{2}\) & \\  & Type & Flexible & \\  & Bandwidth & 50 kHz & \\  & Power of lighting & 10 W & \\  & Number of OLED panels & 19 & \\  & Number of chip/LED panel & 64 & \\  & Power of each chip & 8.2 mW & \\  & Curvature radius & 32 cm & \\ \cline{2-4}  & Location in office & (4, 0.33, 1.5) m & \\ \cline{2-4}  & Location in corridor and semi-open corridor &
\begin{tabular}{c} case1: (0.1, 20, 1.5) m \\ case2: (4.9, 20, 1.5) m \\ \end{tabular} \\ \hline Channel & Time resolution & 0.2 ns \\ \hline \multirow{4}{*}{Rx} & Active area of PD & \(1\) cm\({}^{2}\) \\  & Responsivity & 0.4 A/W \\  & FOV & 90\({}^{\circ}\) \\  & Incident angle & 0\({}^{\circ}\) \\  & One sided noise power spectral density \(N_{o}\) & \(10^{-19}\) W/Hz \\ \hline \hline \end{tabular}
\end{table}
Table 1: The system parameters.  
4 Mb/s, the BER remains below the FEC limit for \(\theta\) within the range of \(\pm 90^{\circ}\) and \(\pm 53^{\circ}\) for the curved and flat OLEDs, respectively. However, for \(R_{b}\) of 6 Mb/s, \(\theta\) drops by \(15^{\circ}\) and \(4^{\circ}\) for the curved and flat OLEDs, respectively.