# Efficient Health Data Transmission Method in a Wireless Body Area Network for Rural Elderly
## 5 Experiment and Analysis
### Network Performance Analysis  
The network lifetime is measured by the number of rounds before a node dies. The fewer the number of dead nodes in a certain period of time, the longer the network lifetime. We compared the studied algorithm with the EEAR algorithm without considering opportunistic routing in ref. [13], the MMR_OR algorithm based on maximum/minimum ranges in ref. [25], and the IOP algorithm using opportunistic routing to transmit health data, reported in ref. [24]. As shown in ref. [13], in order to better aggregate data and run routing algorithms, the sink is considered to be energy-unlimited. Therefore, we mainly verified the energy consumption of the sensor nodes. In Figure 3, we can see that the first dead node of the studied protocol appeared at the latest, around the 200 th simulation round. As the number of rounds increased, the number of dead nodes grew faster, and all nodes died around 560 rounds. In the later stage of the simulation, the death rate of the node increased. After a node died, the probability of forming a reliable transmission route in the WBAN decreased, the number of retransmissions increased, and the energy consumption increased, so the speed of death increased. However, compared with the other three algorithms, the energy consumption of the studied algorithm was more balanced, and the network was more stable. The algorithm selected the routing strategy according to the data priority. On the basis of not affecting the priority transmission of emergency data, the residual energy and link stability were comprehensively considered. Therefore, the energy consumption was more balanced. Although the network energy was not considered when transmitting emergency data, the algorithm still maintained a good network lifetime. The throughput of the network is an important indicator that characterizes the overall performance of the network. Figure 4 shows the changing trend of the number of packets received by the sink. The throughput performance of the studied protocol was better than that of previous protocols. The energy consumption was more balanced, and the network performance was more stable, which ensured the reliability of data transmission and improved the network throughput. It can be clearly seen in the Figure 3 that the last node of the MMR_OR algorithm died around 650 rounds. The last node of MMR_OR died at the latest, but due to unbalanced energy consumption, other nodes died earlier, resulting in a poor throughput. \begin{table}
\begin{tabular}{l l l l} \hline \hline  & **X Coordinate** & **Y Coordinate** & **Z Coordinate** \\ \hline Node1 (sink) & 0 & 0 & 0 \\ Node 2 (stomach) & 0 & h & 0 \\ Node 3 (heart) & 0.5 h & 1.5 h & 0 \\ Node 4 (armpit) & 0.5 h & h & 0 \\ Node 5 (Right knee) & \(-0.5\) h & \(-2\) h & 0 \\ Node 6 (Left knee) & \(-0.5\) h & \(-2\) h & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Node position when the human was static. \begin{table}
\begin{tabular}{l l l l l} \hline \hline  & \(\mathbf{t=0.5\,s}\) & \(\mathbf{t=1\,s}\) & \(\mathbf{t=1.5\,s}\) & \(\mathbf{t=2\,s}\) \\ \hline Node 1 &  
Figure 5 shows the network delay under different algorithms. It can be seen that the delay of our algorithm was shorter than that of other algorithms. This is because the shortest transmission path of emergency data was considered, which made the transmission cost of routing lower. Therefore, compared with other routing algorithms focusing on the transmission distance, the delay of our algorithm was shorter. Figure 6 compares the average hops of each algorithm. When the network energy was abundant in the early stage, the studied algorithm chose to transmit data by one-hop transmission. In the later stage, the energy decreased. The influence of residual energy was introduced into the selection of the candidate set, so the average hop count increased. By comparing the average number of hops and the number of dead nodes, it can be seen that the average number of hops experienced by the route selected by our algorithm was small.