## 3 Experimental Work
After selecting the required scenario (case 3) for the developed OGFDM design, the main system parameters are updated accordingly. The impact of the upgraded PHY on the system performance (channel capacity and BER) is explored for the five levels of manipulation. Thus, such important parameters like the number of subcarriers and sampling frequency size can directly influence the acceleration, filtration, oversampling, allocation, and modulation levels of manipulation. Regarding the acceleration and filtration levels, the developed multi-carrier OGFDM with 6 GHz is mainly compared with the 5G waveform (GFDM) exploring the impact of Hilbert filters on the transceiver process. In addition, despite that the expanded sampling frequency is set to 6 GHz, the effect of extending the initial case of the F\({}_{\text{DAC}}\) from 4 to 6 GHz is also considered for the overall performance. Thus, investigating how the change in sampling frequency can impact the bit-rate of transmission in cooperating with the orthogonal filters that play a big role in improving the BW efficiency and then supporting the channel capacity of the upgraded system. As is seen in Figure 6, in this experiment, a stable 2 dB gain is obtained between the aggregated channel capacity of the OGFDM and the GFDM because of the orthogonality impact of the utilized Hilbert filters on the OGFDM waveform. Thus, a higher channel capacity (double) is achieved with the orthogonal OGFDM than the non-orthogonal GFDM with that root-raised-cosine (RRC) for an equivalent level of the sampling frequency. In addition, because of expanding the applied F\({}_{\text{DAC}}\), 3 dB improvement can be achieved between the OGFDM and the GFDM. The main reason beyond this increment is the combined influence of both the advanced Hilbert filters and the improved sampling frequency. As such, the high channel capacity can be acquired by either improving the BW efficiency (Hilbert pair) or by extra extending the used sampling frequency. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **F\({}_{\text{DAC}}\) (GHz)** & **N\({}_{\text{-Sc}}\)** & **F\({}_{\text{DATA}}\) (MHz)** & **fc (MHz)** & **Sc-Cap (Mb/s)** & **T-Cap (Gb/s)** \\ \hline Case 1 & 4 & 16 & 250 & 125 & 875 & 14 \\ Case 2 & 4 & 32 & 125 & 62.5 & 437.5 & 14 \\ Case 3 & 6 & 32 & 187.5 & 93.75 & 656.25 & 21 \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of expansion trials for multi-carrier OGFDM system. Figure 5: Case 3: F\({}_{\text{DAC}}\) = 6 GHz, \(K\) = 32. Regarding the oversampling level, with the normal oversampling (NOV), where the oversampling factor (\(OV\)) equals to the number of the subcarriers (\(K\)), the interference between filtered subcarriers is decided according to the \(\alpha\) value. To mitigate such an issue, a dual oversampling (DOV) is adopted where the number of produced copies for each utilized subcarrier can be doubled (\(OV=2K\)) for the same utilized centers of frequencies. Therefore, the negative effect of the \(\alpha\) can be accommodated counting on the offered band intervals, which in turn, can remove any possible intra-channel interference. The upgraded OGFDM is compared with the initial OGFDM and GFDM considering the impact of the hybrid treatment (NOV and DOV) on the system performance (channel capacity and BER) at 6 GHz sampling frequency. As is shown in Figure 7, the experimental work indicates that by utilizing the DOV with the upgraded OGFDM at worst transmission states (\(0.5\leq\alpha\leq 1\)), the channel capacity is extremely improved. Thus, 6 dB and 12 dB gains are obtained for the channel capacity of the extended OGFDM with the DOV higher than the conventional OGFDM and GFDM with the NOV. Nevertheless, at a good transmission condition (\(0\leq\alpha\leq 0.4\)), the NOV mode can supply a better transmission rate than the DOV. As such, by employing the NOV with the developed OGFDM at the optimum value of the rolling (\(\alpha=0.1\)), around 2.6 dB and 5.25 dB gains are recorded in comparison with the initial OGFDM and GFDM at DOV mode.