## 6 Evaluation Results
This is due to the lower PAPR of 16-DQPSK which resulted in the RF (Analog) energy consumption performance of both techniques to be almost alike. 16-OQPSK system with complex RF architecture performs better than 16 WOFDM and 16 FOFDM system due to its better BER performance and lower PAPR. 16-WOFDM based system consumes less energy as compared to 16-FOFDM by approximately 40% due to its simpler RF architecture, which reduces the amount of circuit energy it consumes. For the same reason, BPSK-16 WOFDM is also found to consume less energy than BPSK-16 FOFDM by a similar margin. It is also observed that BPSK-16 FOFDM and BPSK-16 WOFDM are more energy efficient than 16-FOFDM, and 16-WOFDM, respectively, mainly  
Figure 8: Total energy per bit per node over transmission distance \(d^{L}=1\) to 100 m.  
due to their lower PAPR. From Figure 8, it is clear that virtual MIMO system is more energy efficient as compared to SISO system due to better BER performance. The base band energy consumption per bit per node (\(E_{b\_Digital}\)) for all modulation types along with their constituting energy consumed by individual modulator, demodulator, and detection algorithm are shown in Table 1. It is observed that each modulator consumes more energy as compared to demodulator due to its higher computational complexity (in terms of CPU cycles per bit). For similar reasons, 16-DQPSK consumes less \(E_{b\_Digital}\) as compared to other modulation techniques. Since SISO system does not need to perform V-BLAST detection on receiver side (hence \(E_{Det}\) is negligible), the \(E_{b\_Digital}\) of BPSK-16 WOFDM with virtual MIMO is higher as compared to that of the SISO system. Table 2 shows the RF (Analog) energy consumption (\(E_{b\_Analog}\)) at different transmission distances values and total energy consumption (\(E_{b\_Total}=E_{b\_Analog}+E_{b\_Digital}\)). It is clear from Section 5.1.2 that \(E_{b\_Digital}\) is independent of transmission distance. For short distance (\(d^{L}\leq 25m\)), \(E_{b\_Digital}\) has significant effect on \(E_{b\_Total}\). However, as \(d^{L}\) increases, \(E_{b\_Analog}\) increases, which reduces the effect of \(E_{b\_Digital}\). 16-WOFDM performs better for short distance (\(d^{L}\leq 25m\)) as compared to BPSK-16 FOFDM, 16 FOFDM, 16-QOPSK and BPSK-16 WOFDM as a result of a lower \(E_{b\_Digital}\). For larger distances \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Modulation Type**} & \multicolumn{2}{c}{\(E_{Mod}\) **per**} & \(E_{Dmod}\) & \(E_{Det}\) & \(E_{b\_Digital}\) \\  & **bit in dBJ** & **per bit in dBJ** & **per bit in dBJ** & **per bit per node in dBJ** \\ \hline
16-DQPSK & –31.7203 & –32.1389 & –30.7033 & –31.2591 \\
16-QAM & –31.2628 & –31.9686 & –30.7033 & –30.9803 \\
16-OQPSK & –30.8951 & –31.1203 & –30.7033 & –30.4600 \\
16-FOFDM & –30.0134 & –30.7192 & –30.7033 & –29.8781 \\
16-WOFDM & –31.0294 & –31.7203 & –30.7033 & –30.8009 \\ BPSK-16 FOFDM & –29.86 & –30.587 & –30.7033 & –29.8167 \\ BPSK-16 WOFDM & –30.8764 & –31.2681 & –30.7033 & –30.5142 \\ SISO-BPSK-16 WOFDM & –30.8764 & –31.2681 & –\(\infty\) & –31.0678 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Base Band (Digital) Energy Consumption.