# Toward an Advanced Human Monitoring System Based on a Smart Body Area Network for Industry Use
## 3 System Model
### Modified PHY  
As shown in Table 1, the maximum throughput of the SmartBAN PHY was 1.0 tMbit/sec. Thus, it was not enough to transmit and receive data from all the sensors shown in Table 4. In other words, the data rate of the SmartBAN PHY needed to be improved. Two approaches were considered in this research. The first approach was applying multilevel PSK modulation to the SmartBAN PHY. Multilevel PSK modulation is available in other types of short-range wireless communication technology, such as \(\pi/4\)-differential quadrature phase shift keying (DQPSK) and \(\pi/8\)-differential eight phase shift keying (DQPSK) in the Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) and IEEE Std. 802.15.6. Hence, these modulation schemes could be applied to the sensors used in the SmartBAN PHY. In this instance, the preamble structure was mentioned when the multilevel PSK was applied. The modified preamble structure was proposed in [32]. The reason for this was that the preamble structure shown in Figure 1 was too simple to perform highly reliable communication dealing with medical and healthcare information. To correctly detect the position of the PLCP header, an start \begin{table}
\begin{tabular}{c c} \hline \hline
**User Priority** & **Data Type** \\ \hline
0 & Low Priority \\
1 & Mid Priority \\
2 & High Priority \\
3 & Very High (Emergency) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: List of user priorities. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**User Priority**} & \multicolumn{2}{c}{**Contention Probabilities**} \\ \cline{2-3}  & \(\text{CP}_{\text{max}}\) & \(\text{CP}_{\text{min}}\) \\ \hline
0 & 1/8 & 1/16 \\
1 & 1/4 & 1/16 \\
2 & 1/2 & 1/8 \\
3 & 1 & 1/2 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Contention probabilities for different user priorities. frame delimiter (SFD) was added between the two-octet preamble and the PLCP header. Cross-correlation was performed on the known modulated SFD symbol when detecting the header position. However, the number of preambles and SFD symbols decreased according to the number of multilevels when multivalued PSK was applied; that is, the header detection capability deteriorated, since the cross-correlation value decreased. Therefore, this problem was addressed by repeating the preamble and the SFD according to the number of multilevels. Figure 4 shows the case where \(\log_{2}M=2\). In this equation, \(M\) denotes the number of multilevels. The second approach was increasing the symbol rate, with that of SmartBAN being 1.0 Msps as shown in Table 4. On the other hand, each channel bandwidth was 2 MHz. Hence, the symbol rate may have been increased. Figure 5a-c illustrates the normalized power spectral density (PSD) of GFSK and PSK in the constant symbol rate case [33]. As shown in those figures, it was possible to suppress intersymbol interference with adjacent channels by applying a raised cosine filter having a roll-off rate of 0.33 to PSK modulation for the case where the symbol rate was 1.5 Msps. On the other hand, intersymbol interference to adjacent channels due to out-of-band radiation could not be avoided in the case \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sensor Number** & **Sensor Type** & **Target Data Rate (\(R_{i}\))** & **User Priority** \\ \hline
1 & SpO2 & 17.3 kbps & 1 \\
2 & ECG & 24 kbps & 1 \\
3 & Accelerometer & 1.2 kbps & 1 \\
4 & Pulse rate & 8 bps & 0 \\
5 & Blood pressure & 8 bps & 0 \\
6 & Temperature & 8 bps & 0 \\
7 & Audio (downlink) & 128 kbps & 2 \\
8 & Video (downlink) & 700 kbps & 2 \\
9 & Audio (uplink) & 128 kbps & 2 \\
10 & Video (uplink) & 500, 700, 1100 and & 2 \\  & & 2500 kbps & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: List of sensors and target data rates. Figure 3: Supposed use case. The artificial intelligence (AI)-based operator monitors the vital data of the worker in the factory wearing the smart body area network (SmartBAN). where the symbol rate was 2.0 Msps. Hence, this case needed to monitor the use status of the adjacent channel.