# Toward an Advanced Human Monitoring System Based on a Smart Body Area Network for Industry Use
## 4 Results and Discussion
### PHY Performance
#### 4.1.4 Link Budget and Receiver Sensitivity  
The link budget is calculated as follows:  
\[ \begin{split} P_{\text{rx}}=P_{\text{tx}}+G_{\text{tx}}-L_{\text{tx}} -L_{\text{path}}+G_{\text{rx}}-L_{\text{rx}}\\ L_{\text{path}}=L_{\text{fs}}+L_{\text{m}}\end{split}  \tag{19}\]  
In this equation, \(P_{\text{rx}}\) and \(P_{\text{rx}}\) are the receiver and transmitter power, respectively, \(G_{\text{tx}}\) and \(G_{\text{rx}}\) are the antenna gain at the transmitter and receiver, respectively, and \(L_{\text{tx}}\) and are the transmitter and receiver losses, respectively. \(L_{\text{path}}\) is a path loss, \(L_{\text{fs}}\) is a free space loss, and \(L_{\text{m}}\) is miscellaneous losses, such as fading loss and body loss. When \(P_{\text{tx}}\) = 4 dBm, \(G_{\text{tx}}\) and \(G_{\text{rx}}\) = 3 dBi, \(L_{\text{tx}}\) and \(L_{\text{rx}}\) = 3 dB and \(L_{\text{path}}\) = 53.9 dB (calculated by Equation (6)), the calculation example of the link budget is as follows:  
\[P_{\text{rx}}=4+3-3-53.9+3-3=-49.9\text{ dBm} \tag{20}\]  
Then, the receiver sensitivity (\(S_{\text{dBm}}\)) and the fade margin are also calculated as follows:  
\[S_{\text{dBm}}=-174\text{ }(\text{dBm})+NF_{\text{dB}}+E_{b}/N_{0}\text{ }(\text{dB})+10\log_{10}R_{s}+I_{\text{dB}} \tag{21}\]  
\[E_{b}/N_{0}=E_{s}/N_{0}\times R_{c}/\log_{2}M \tag{22}\]  
\[\text{Fade margin}=P_{\text{rx}}-S_{\text{dBm}} \tag{23}\]  
In this equation, \(NF_{\text{dB}}\) is a noise value, \(R_{c}\) is a coding rate and \(I_{\text{dB}}\) is an implemental loss. Tables 10 and 11 summarize examples of \(S_{\text{dBm}}\) under the AWGN channel in the case of \(\text{PER}\leq 10^{-2}\) and \(10^{-3}\), respectively. Tables 12 and 13 also summarize examples of fade margins in cases where \(\text{PER}\leq 10^{-2}\) and \(10^{-3}\), respectively. As shown in Tables 8 and 9 again, the differences in \(E_{s}/N_{0}\) satisfying \(\text{PER}\leq 10^{-2}\) and \(10^{-3}\) between the AWGN channel and the IEEE model CM3 in the medium shadowing case were approximately 8.5 dB and 15 dB, respectively. Hence, it can be said that the fade margin was sufficiently obtained from those tables without using an ECC. On the other hand, those between the AWGN channel and the IEEE model CM3 in the strong shadowing case were approximately 15 dB and 26 dB, respectively. Comparing them with Tables 12 and 13, the sufficient fade margin could be obtained in a case where \(\text{PER}\leq 10^{-2}\), while it was also found that the uncoded \(\pi/4\)-DQPSK and D8 PSK did not provide a sufficient fade margin in a case where \(\text{PER}\leq 10^{-3}\). However, it can be said that those modulation schemes were also sufficiently useful, because the energy efficiency was sufficiently large even in cases where \(\text{PER}\leq 10^{-2}\). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Channel Model** & **ECC** & **GFSK** & **QPSK** & **\(\pi/4\) Shift DQPSK** & **D8 PSK** \\ \hline \multirow{3}{*}{AWGN} & No ECC & 11.8 & 13.5 & 16.9 & 21.6 \\  & (127, 113) & 9.8 & 10.2 & 12.9 & 18.3 \\  & (127, 85) BCH & 7.6 & 8.0 & 11.0 & 16.2 \\ \hline \multirow{3}{*}{CM3 (medium shadowing case)} & No ECC & 26.0 & 28.5 & 31.2 & 36.4 \\  & (127, 113) & 24.0 & 26.2 & 28.5 & 34.8 \\ \cline{1-1}  & (127, 85) BCH & 22.8 & 24.0 & 27.0 & 31.2 \\ \hline \multirow{3}{*}{CM3 (strong shadowing case)} & No ECC & 37.0 & 40.1 & 42.6 & 48.4 \\  & (127, 113) & 35.1 & 37.6 & 40.1 & 45.2 \\ \cline{1-1}  & (127, 85) BCH & 34.2 & 35.1 & 38.0 & 42.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: \(E_{s}/N_{0}\) (dB) satisfying \(\text{PER}\leq 10^{-3}\).