## 3 Results and Discussion
Figure 7 illustrates the variation in the bit error  
Figure 5: Data rate as a function of signal-to-noise ratio and transmitter power for BPSK modulation. Figure 6: The data rate varies based on the transmitter power and the signal-to-noise ratio for QPSK modulation. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Data Rate (Gbps)** & **BER** \\ \hline SNR = \(-20\) dB, P = 10 \(\upmu\)W & \(7.38\times 10^{-7}\) & 0.4996 \\ \hline SNR = 10 dB, P = 5 mW & 5.6 & \(7.37\times 10^{-7}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Minimum and maximum BER and data rate values for QPSK modulation. rate with the transmitter power and signal-to-noise ratio. The bit error rate is increased for this modulation compared to BPSK modulation. Further, 16 QAM modulation is used in optical communication channels with a medium SNR, which must balance the data rate and optical channel reliability. This modulation offers a higher data rate compared to BPSK and QPSK modulations. Figure 8 and Table 4 show that as the transmitter power and SNR increase, the data rate values rise to 11.21 Gbps under comparable channel conditions. The bit error rate variation in the transmitter power and SNR for 16 QAM modulation is shown in Figure 9. This model's minimum and maximum values for the BER are \(2.56\times 10^{-5}\) and \(0.3748\), respectively. It has been observed that the BER in this model has increased compared to lower-order modulations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Data Rate (Gbps)** & **BER** \\ \hline SNR = \(-20\) dB, P = \(10\)\(\upmu\)W & \(1.47\times 10^{-6}\) & \(0.3748\) \\ \hline SNR = \(10\) dB, P = \(5\) mW & \(11.21\) & \(2.56\times 10^{-5}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Minimum and maximum BER and data rate values for 16 QAM modulation. Figure 8: Data rate variations depending on transmitter power and SNR for 16 QAM modulation. Figure 7: Variations in bit error rate as a function of transmitter power and SNR for QPSK modulation. High-order modulations, such as 64 QAM, are used to modulate optical communication channels where high data rates are essential. Figure 10 shows that this model's data rate is higher than that of previous models. According to Table 5, the maximum data rate in this case is 16.81 Gbps. Figure 10 shows the data rate changes regarding the transmitter power and BER for 64 QAM modulation. The bit error rate in an optical communication channel with 64 QAM modulation decreases less for higher transmitter power values than with previous modulations. Figure 11 illustrates the bit error rate for 64 QAM modulation as a function of the transmitter power and SNR. In this case, the minimum and maximum bit error rates are \(5.1\times 10^{-3}\) and \(0.2916\), respectively. Figure 10: Variations in data rate based on transmitter power and bit error rate for 64 QAM modulation. \begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Data Rate (Gbps)** & **BER** \\ \hline SNR = \(-20\) dB, P = 10 \(\mu\)W & \(2.21\times 10^{-6}\) & 0.2916 \\ \hline SNR = 10 dB, P = 5 mW & 16.81 & \(5.1\times 10^{-3}\) \\ \hline \end{tabular}
\end{table} 
Table 5: Minimum and maximum BER and data rate values for 64 QAM modulation. Figure 9: Changes in bit error rate as a function of transmitter power and SNR for 16 QAM modulation. In a wireless optical communication channel that is affected by fog, the power at the receiver decreases due to path loss, resulting in a reduced data transmission rate. Figure 12 illustrates the variations in the data rate based on the signal-to-noise ratio and transmitter power for BPSK, QPSK, 16 QAM, and 64 QAM modulations. It is evident from this figure that the data rate is lower for modulation schemes with lower-order OFDM. The Gamma-Gamma distribution model accounts for fading effects in wireless communication channels on both large and small scales. Implementing this model involves more complex analytical relationships compared to other models.