# Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities
## 5 Result Analysis and Discussion  
The evaluation of FFT-OFDM and DCT-OFDM augmented by MRC receiver diversity scheme is presented for image transmission. In Figures 4-7, a visual representation of image quality is presented for FFT-OFDM and DCT-OFDM using MRC (1 Tx and 1, 2, 3 Rx) under AWGN and Rayleigh channel. The comparison is done for diverse modulation schemes, and the representation is presented for various SNR values. It is apparent from the representations that as the modulation level keeps growing, the image quality is degrading at a particular SNR value. However, if we increase the SNR from 5 dB 15 dB, the improvement in the received image quality can be seen. It is also quite evident from the comparison that it can also be detected as we raise the number of receiving antennas from 1 to 2, and in 3 the image quality enhances in both the FFT-OFDM and DCT-OFDM. This is because the receiver diversity provided by MRC schemes minimizes the effect of the channel environment on the signal. The use of multiple receivers at the receiver side provides a better quality of data reception than a single antenna at the receiver end. The comparison of Figures 4 and 5 also depicts that the received image quality is better in case of DCT-OFDM in comparison to FFT-OFDM. However, the image quality got affected under the influence of Rayleigh fading channel. Figure 4: Received Image with FFT-OFDM over a AWGN channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L \(\Rightarrow\) R with MRC (nTx = 1 and nRx = 1 and 2). Figure 5: Received Image with DCT-OFDM over a AWGN channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L \(\Rightarrow\) R with MRC (nTx = 1 and nRx = 1 and 2). Figure 6: Received Image with FFT-OFDM over a Rayleigh channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L \(\Rightarrow\) R with MRC (nTx = 1 and nRx = 1 and 2). Tables 2-5 illustrate the variations of the PSNR with SNR for both FFT-OFDM and DCT-OFDM (with and without MRC) over AGN channel, and Tables 6-9 illustrates the variations of the PSNR with SNR for both FFT-OFDM and DCT-OFDM (with and without MRC) over Rayleigh fading channel employing diverse modulation schemes for the RGB Lena image, similar results will also be there for other images. It is very much clear from the observations of Table 2 that there is a significant increase in the PSNR values for both FFT-OFDM and DCT-OFDM on employing the MRC schemes with 1 Tx and 2 Rx antennas. In the case of BPSK at SNR = 0 dB, the PSNR value is 9.33109 dB, and it is increased up to 15.8195 dB for FFT-OFDM. Similar inference can be made out by observing the values for DCT-OFDM for BPSK at SNR = 0 dB, in which the PSNR value increases up to 21.1769 dB from 10.8239 dB on employing the MRC scheme with 1 Tx and 2 Rx antennas. Further, it can be observed that PSNR also enhances as we switch from FFT-OFDM to DCT-OFDM for all SNR values and both with MRC and without MRC schemes. Similar observations can be made from Tables 3-9 that the PSNR value enhances as we switch from FFT-OFDM to DCT-OFDM. Additionally, the PSNR value enhances on employing the MRC scheme with 1 Tx and 2 Rx antennas. This increase in PSNR values results in significant improvement in the quality of the image at the receiver end. Moreover, the PSNR decreases under the influence of Rayleigh fading channel as presented in Tables 6-9. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**SNR**} & \multicolumn{2}{c}{**FFT-OFDM**} & \multicolumn{2}{c}{**DCT-OFDM**} \\ \cline{2-5}  & **1 Tx and 1 Rx** & **1 Tx and 2 Rx** & **1 Tx and 1 Rx** & **1 Tx and 2 Rx** \\ \hline
**0 dB** & 9.33109 & 15.8195 & 10.8239 & 21.1769 \\ \hline
**5 dB** & 11.1558 & 27.0993 & 12.1698 & 42.7428 \\ \hline
**10 dB** & 14.3648 & 58.0264 & 19.2917 & 60.2544 \\ \hline
**15 dB** & 22.5041 & 69.4254 & 36.3608 & 73.5611 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: PSNR values for FFT-OFDM and DCT-OFDM for BPSK with MRC (nTx = 1 and nRx = 1, 2) over AWGN Channel.