# OFDM Network Optimization Using a QPSK Based on a Wind-Driven Genetic Algorithm
## 5 Results
### Results Analysis  
Tables 4 and 5 give a much clearer comparison of the BER for the two modulation schemes. The channel properties and simulation settings that were used are given in Section 4. From Tables 4 and 5, in a noiseless channel, the GAWDO QPSK has no BER. The transmitted signal is recovered with high fidelity. No distortion occurs. For the customary QPSK, it experiences bit errors of up to 7.8%. In a noisy channel, the GAWDO QPSK had bit errors not exceeding 8% but the customary QPSK had bit errors going beyond 17%. This highlights the challenges that the customary QPSK fails to overcome. These high bit errors are caused by the system failing to maintain linearity even under a noiseless/clean operating scenario. This also shows that carrier offset drift and phase ambiguities remain a major cause for concern since the customary QPSK phases are fixed according to the constellation diagram [7; 8]. In a noisy channel, ISI and ICI are rife and this caused the BER to compound significantly. In a real-world scenario where multipath fading is of great detrimental effects, the BER values obtained through simulation by this research can double [21]. This means that as much as the customary QPSK is popular, it does not offer very satisfactory results. From Table 5, in a noisy channel, the GAWDO QPSK shows better resilience under harsh conditions. It shows immunity to carrier offset drift and very few occurrences of phase ambiguity. The GAWDO QPSK demonstrates much better robustness to noise and adverse channel conditions. This is seen by its low bit errors which do not go beyond 8% regardless of the fading properties of the channel. This also implies that the GAWDO presents a system that has great coherence between the modulation and demodulation stages. Most traditional systems struggle with this \begin{table}
\begin{tabular}{c c c} \hline \hline
**Data Points** & **GAWDO QPSK \% Error** & **Customary QPSK \% Error** \\ \hline
64 & 0 & 4.69 \\
256 & 0 & 7.81 \\
1024 & 0 & 4.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: BER comparison between GAWDO and customary QPSK in a noiseless OFDM network. Figure 15: Customary QPSK output for 1024 data points in a noisy channel. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Data Points** & **GAWDO QPSK \% Error** & **Customary QPSK \% Error** \\ \hline
64 & 1.56 & 9.38 \\
256 & 3.51 & 17.58 \\
1024 & 7.52 & 12.79 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: BER comparison between GAWDO and customary QPSK in a noisy OFDM network. aspect [32]. Data loss and phase misappropriations are also low when using the proposed GAWDO QPSK. Figures 4-15 and Tables 4 and 5 show that the enhanced modulation scheme gives more accurate results. With the increasing demand for bandwidth efficiency and higher data throughput [32; 33], the proposed algorithm offers a solution that gives more accurate results regardless of the channel conditions and environment. The proposed methodology also offers solutions for systems that need the least possible amount of bit errors and distortions. During simulations, the GAWDO QPSK takes more computational time as compared to the customary QPSK. This is because the GAWDO undergoes numerous evolutionary cycles in determining the best phase assignments during modulation. However, for similar data points, the time difference between the GAWDO QPSK and the customary QPSK is less than 1 min as shown in Figure 16. This is not very significant when considering the quality of results that will be obtained. BER not exceeding 8% as compared to the conventional QPSK which gave BER magnitudes beyond 17%. The simulation results showed that the proposed modulation technique can easily overcome the challenges that the customary QPSK fails to subdue. In future work, we intend to use the GAWDO to enhance other higher-order modulation techniques, e.g., 256 QAM or 1024 QAM and investigate its performance over the existing methods.