## 1 Introduction  
A Wireless Body Area Network (WBAN) consists of intelligent and low-power computing devices that are used to collect patients' vital signs for real-time diagnosis and remote health monitoring. These devices forward the collected information to a central sink node that forwards it to a medical server. Unlike the typical Wireless Sensor Networks (WSN), there are several routing issues in WBAN due to its stringent requirements [1]. For example, the main objective of routing protocol in a WSN is to minimize the routing overhead and maximize throughput. On the other hand, in WBAN, it is more important to reduce energy consumption because sensor devices have limited resources in terms of battery capacity, transmission power and memory. In addition, since WBAN collects physical data of the human body, it is also important to reduce packet loss and transmission delay. One of the important challenges in WBANs is the temperature rise of each device. When computing and traffic forwarding are concentrated on a specific device, the temperature of the device rises sharply which leads to damage of surrounding body tissues. To address this problem, multiple researchers have proposed several temperature-aware routing protocols. For example, TARA is one of the first protocols that considers nodes' temperature when selecting the next hop [2]. In TARA, the temperature of the nodes using the pennes bio heat equation [3] is estimated and used for next hop selection in a way that the neighbor with the lowest temperature is chosen until the data packet reaches its destination. However, there is a high possibility that a packet may go through many intermediate nodes until it arrives at its destination. ALTR [4] takes the same mechanism as TARA, but Shortest Hop Routing (SHR) algorithm is performed whenever the hop count field of a packet header exceeds the pre-defined threshold. On the other hand, HPR [5] forwards the data packet to a neighbor with the smallest number of hop count to the destination. However, if the temperature of the selected node exceeds the pre-defined threshold, instead a neighbor with the lowest temperature is selected as the next hop. However, since all these mentioned approaches simply consider one hop information for temperature, many packets return to the previous node. To solve this problem, Enhanced Temperature-aware Routing Protocol (ETARP) [6] exploits two hops ahead scheme. The two hops ahead algorithm contributes to selecting the proper path at an earlier time in a way that it can observe the hot spot region in advance by calculating the temperature cost, which includes the temperature of its two hop neighbors. As described earlier, lots of research has been proposed to address the temperature rise of the node, however, their approaches naturally cause other problems such as delay or loss of data because they assume fixed network topology. This implies that dynamic network topology changes caused by movement of human posture are not taken into account in the previous work. To mention the technical issues in the dynamic topology, [PERSON] et al. presented research challenges for mobility support in a WBAN [7]. The authors of [8] proposed a temperature-aware routing protocol called M-ATTEMPT that considers the mobility of a human body. The network topology of M-ATTEMPT is based on the tree structure that is rebuilt by a node's joining to the new parent node whenever a node changes its location. In addition, each node can simply prevent its temperature rise by disconnecting with all links from its neighbors when the node's temperature reaches the threshold. On the other hand, Mobility and Temperature-aware Routing (MTR) [9] utilizes the mobility of the human body in the routing process. When the temperature of all neighboring nodes exceeds the pre-defined threshold, a mobile node attached to the arms and legs is selected as a next hop in order to forward the data packet to the sink directly by adapting the store and carry scheme.