# BNS: A Framework for Wireless Body Area Network Realistic Simulations
## 4 Use Cases
### Analysis of Temperature Behavior  
In WBAN, preventing nodes from overheating is a challenge that requires special attention. In [9], the Link-Quality Aware and Thermal-Aware On-Demand Routing (LATOR) protocol for routing in WBAN is proposed. LATOR is projected to avoid overheating and improve performance in sensing. For that, in [9] the authors propose a mechanism  
Figure 10: Distribution of packet’s latency in application layer. Figure 9: Measurement packets successfully delivered to the manager per node. that chooses routes without heated nodes and when an intermediate node reaches the heated state, the choice of a new relay node is activated. That mechanism of overheating prevention is based on controlling the node's activity, where a heated node does not carry out any transmission and enters a low consumption mode. On the other hand, Link Quality Information (LQI) is collected during the route discovery phase. Then, sensor nodes will use LQI-based metrics to forward DATA packets [9]. In this use case, a simulation is carried out to analyze the temperature behavior of the network nodes. The WBAN topology used is the same used in Section 4.1. The mobility of the body is considered, and the channel behavior used is the David channel model proposed in [23]. A generic sensor node was used in the application layer, with settings valid for medical sensors with low transmission rates. The PHY and MAC layer configurations used were those described in the WBAN standard and available in the BNS framework. Settings of the thermal parameters of the tissues of the human body are the same used in [9]. Similar to the work presented in [9], for comparison purposes in this use case, DRR, First Route Available Routing (FRAR), Link-Quality Aware On-Demand Routing (LAOR) and LATOR protocols were considered. These protocols are covered in [9], and in this paper we follow the same settings. To analyze the performance of the proposed overheating prevention method, a temperature increase limit of 0.0017 \({}^{\circ}\)C was defined for sensor nodes. The simulation time was ten thousand seconds. The metric observed was temperature increase. For the purpose of this use case, the behavior of the temperature of the network nodes is analyzed when the node located in the left arm (node 1) is the transmitting node. Figure 11 shows the behavior of the temperature using different routing protocols. As it can be seen in Figure 11a, using the first available route, route 1-0 was used 100% of the time. Therefore, no intermediate node showed an increase in temperature. However, it can be seen in Figure 11b that for the LAOR protocol, node 2 experiences a greater increase in its temperature in the first 3800 s, because most of the time it acts as a relay node for node 1 on route 1-2-0. When the LATOR protocol is used, as shown in Figure 11c, the temperature of node 2 begins to increase until reaching the defined limit. This increase is due to the fact that node 2 is used more times as a relay, because route 1-2-0 has the best quality for forwarding the data transmitted by node 1. As a result, the temperature of node 2 begins to increase until it reaches the defined limit value. This value is reached for the first time at 3180 s.  
At that moment, node 2 sends its heating notification to the transmitting node. Node 1, when it receives the notification, switches routes, and starts using the direct path. At that moment, node 2 starts to cool. Immediately thereafter, there are two more peaks at which node 2 again reaches the defined temperature limit. Between the first and the third peaks in the temperature of node 2, there were exchanges of routes, where the use of node 2 was resumed as a relay. In these cases, the change of route was not generated by heating, but by breaks in the link while using routes 1-0, 1-3-0 and 1-4-0. After the third temperature peak of node 2, route 1-3-0 begins to be used, until node 3 reaches the maximum allowed temperature. In this case, it is node 3 that activates a new route discovery to avoid overheating.