## 6 Evaluation Results
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Modulation Type**} & \multicolumn{4}{c}{\(E_{b\_Analog}\)} & \multicolumn{4}{c}{\(E_{b\_Total}=E_{b\_Analog}+E_{b\_Digital}\)} \\ \cline{2-9}  & \multicolumn{4}{c}{**per bit per node in dBJ**} & \multicolumn{4}{c}{**per bit per node in dBJ**} \\ \cline{2-9}  & \multicolumn{4}{c}{\(d^{L}=25m\)} & \(d^{L}=50m\) & \(d^{L}=75m\) & \(d^{L}=100m\) & \(d^{L}=25m\) & \(d^{L}=50m\) & \(d^{L}=75m\) & \(d^{L}=100m\) \\ \hline
16-DQPSK & –29.0354 & –11.4148 & –1.1630 & 6.4758 & –26.9961 & –11.3700 & –1.1587 & 6.4765 \\
16-QAM & –29.5144 & –11.8938 & –1.6419 & 5.9967 & –27.1754 & –11.8405 & –1.6369 & 5.99766 \\
16-QOPSK & –48.4654 & –30.6948 & –20.6230 & –12.6442 & –30.3918 & –27.5655 & –20.1940 & –12.5729 \\
16-FOFDM & –44.0580 & –26.2874 & –16.2156 & –8.2368 & –29.7153 & –24.7115 & –16.0327 & –8.20722 \\
16-WOFDM & –46.0988 & –28.4682 & –18.4363 & –10.4776 & –30.6746 & –26.4695 & –18.1914 & –10.4374 \\ BPSK-16 FOFDM & –50.7654 & –33.2648 & –22.9930 & –15.1242 & –29.7819 & –28.1969 & –22.1730 & –14.9792 \\ BPSK-16 WOFDM & –52.9461 & –35.2855 & –25.2637 & –17.2949 & –30.4894 & –29.2648 & –24.1293 & –17.09279 \\ SISO-BPSK-16 WOFDM & –30.402 & –17.285 & –7.263 & 0.705 & –27.7118 & –17.107 & –7.2449 & 1.1769 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: RF (Analog) Energy Consumption and Total Energy Consumption. BPSK-16 WOFDM performs better because of a lower \(E_{b\_Analog}\). For all transmission distances, \(E_{b\_Analog}\) and \(E_{b\_Total}\) of SISO system with BPSK-16 WOFDM are higher as compared to virtual MIMO system with BPSK-16 WOFDM. As discussed, the base band (digital) energy consumption and RF (analog) energy consumption is the energy consumed by the CPU, and radio transceiver, of the sensor nodes, respectively. We assume that both the CPU and radio transceiver has two active states (Transmit and Receive). For the CPU, the energy consumption in Transmit mode is the base band energy consumed by the digital modulator (hence depends on the modulation type) for processing each bit for transmission. On the other hand, the CPU or processing energy consumption in Receive mode is the base band energy consumed by the digital demodulator and V-BLAST detection algorithm. The overall energy consumption per bit per node in Transmit mode (\(E_{b\_Total\_Tx}\)) and Receive mode (\(E_{b\_Total\_Rx}\)) for \(d^{L}=20\;m\) are shown in Table 3. \(E_{b\_Total\_Tx}\) is the sum of \(E_{Mod}\) and \(E_{b\_Analog\_Tx}\) while \(E_{b\_Total\_Rx}\) is the sum of \(E_{Dmod}\), \(E_{Det}\) and \(E_{b\_Analog\_Rx}\), where \(E_{b\_Analog\_Tx}\) and \(E_{b\_Analog\_Rx}\) refers to the RF (analog) energy consumption by the transmitter circuits, and receiver circuits, of the radio transceiver, respectively, shown in Figures 5 and 6. The CPU is also assumed to have two inactive states (Idle and Sleep), which are low power modes during which different functions of the CPU are shutdown to save power. To calculate the CPU energy consumption in these modes, we used the voltage and current values for these modes given in the data sheet of MSP430F1611 (the CPU model of TelosB mode). The CPU energy consumption per second in idle and sleep mode is found to be \(-39.5860\) dBJ, and \(-56.1618\) dBJ, respectively. For the radio transceiver, we assume that whenever it is not transmitting or receiving, it will be put into sleep, _i.e._, it has sleep mode as its only inactive state. The energy consumed by the transceiver in sleep mode will depend on the selected radio components that remain on during sleep state, which is design-specific. However, for most existing transceivers for WSNs, the _sleep-to-receive_ energy consumption ratio is about 0.001, _i.e._, the energy consumed in sleep mode is typically about 0.1% of the energy consumed in receive mode.