## 4 Experimental Details and Results for VLC Using Designed Lamp

Table 1: Experimental parameters of the received signal were obtained from its eye diagram, jitter or TIE histogram, and FFT. Figure 10: (**a**) and (**b**) show the signal eye diagram for WL and DL, respectively; clean eye for DL is obtained with less rounding of edges; (**c**) illustrates the schematic composition of total jitter by convolution of random and deterministic jitter; here, dual delta Dirac represents the deterministic component or any kind of sinusoidal modulation present in the signal; (**d**) and (**e**) show the timing interval error (TIE) histogram for WL and DL, respectively. It is bimodal due to the presence of jitter components and shows that the peak-to-peak jitter observed for DL is 27 \(\upmu\)s less than that of WL. The 3 dB bandwidth of the test signal on an oscilloscope screen was captured at a sampling rate of 200.0 kSa/s and a memory depth of 60 k points. The maximum magnitude for both signals was 40 dBm at dc-frequency. Typically, the 3-dB bandwidth of white LEDs is in the MHz range. The 3-dB bandwidth for the WL was 984 Hz, while for the DL, it was 994 Hz, as indicated in Table 1. There is a slight increase in bandwidth for (DL) compared to (WL), possibly due to either the color crosstalk in DL or increased Q-factor. Bandwidth typically increases with current density [60; 61; 62]; however, LEDs experience efficiency droop [63]. LEDs' \(-3\) dB modulation bandwidth rises with higher current density due to a reduction in carrier lifetime. Conversely, the increase in \(-3\) dB modulation bandwidth decreases with rising current density due to a slower rate of carrier concentration growth and enhanced electron leakage [64]. Figure 11 shows MATLAB (R2020b) plotting the PSD from 10 M data samples. The frequency domain representation of a PRBS test signal is a line spectrum bounded by a sinc function whose initial null point equals its bit rate. The baseband spectrum is symmetrical about dc-frequency, and the null-to-null bandwidth is twice the bit rate [51]. Figure 11 shows that a 2-kbps data transfer rate corresponds to the first frequency spectrum null at 2 kHz and a 4 kHz null-to-null bandwidth. Figure 12 shows the signal autocorrelation of the received signal to confirm DL bandwidth increment. We have fabricated the light source using multi-colored LEDs to improve CRI (90), CCT (5114 K), and CIE 1931 coordinates (0.33, 0.33) of conventional white light. Keeping the illuminance conditions the same, nearly 21 Lux for these sources were used. Signal integrity is analyzed using an eye diagram, jitter analysis, and PSD (FFT and autocorrelation). Figure 11: Normalized one-sided power spectral density of PRBS signal (\(2^{11}-1\)) using DL and WL as sources of transmitting data by intensity modulation and direct detection technique. The FFT of a PRBS code generates a line spectrum bounded by a sinc function in terms of magnitude. Here, A data transfer rate of 2 kbps corresponds to the first null of the frequency spectrum (which resembles a sinc envelope) at 2 kHz. Due to the symmetrical nature of the baseband spectrum near DC, the null-to-null bandwidth is equal to twice the bit rate, which is 4 kHz. The inset shows the zoomed section of the dc component.