## 2 Related Work  
The authors of [2] proposed the first temperature-aware routing protocol for WBAN. In TARA, a data packet is forwarded to a neighbor node with the lowest temperature until it is delivered to a sink node. However, if the temperature of a neighbor node with the lowest temperature exceeds threshold, the data packet is sent back to the node that had forwarded the data packet previously. Thus, TARA leads to the temperature rise of many intermediate nodes because a packet might have to go through them until it arrives at its destination. To overcome this problem, ALTR [4] has been proposed. In ALTR, the data packet is forwarded to a neighbor node with the lowest temperature in normal condition. Otherwise, it is forwarded to a neighbor node with the smallest number of hops to the destination when the hop count of the packet header exceeds the pre-defined threshold. Similarly, HPR [5] selects a neighbor node with the smallest number of hops as a next hop. On the other hand, it selects a neighbor node with the lowest temperature when the temperature of the selected node is greater than the pre-defined threshold. Unlike the previous approaches that consider neighbor nodes' temperature only, ETARP [6] exploits the two hops ahead scheme while considering the short distance between each node and a sink. For example, as shown in Figure 1, the previous works take node A as a next hop because it has a lower temperature than B. However, all packets forwarded to node A cannot forward any more because both node C and D are hot spots now. To avoid this situation, MTARP takes the neighbor nodes' temperature cost within its two as well as one hop. As a result, node B is selected as a next hop because the temperature cost of node B including the temperature of its two hop neighbors is lower than node A. However, previous temperature-aware routing protocols did not support QoS requirements. TMQoS [11] integrates the QoS support issue with temperature-awareness in the routing process. TMQoS classifies the data packet into four types according to the importance of data, and creates different routing paths using cross-layer framework module such as temperature module, reliability module, and delay module. TLQoS [12] also uses a cross-layer framework like TMQoS, but it is based on the greedy forwarding algorithm that selects the neighboring node with the greatest routing cost as the next hop, rather than generating the routing path according to the data types. TTRP [13] provides reliable and secure data transmission. To avoid malicious node, it calculates the trust value by counting the total number of forwarded packets and actual received packets. The routing cost is calculated by adding the weighted trust value and the weighted temperature of the node. However, previous approaches have problems such as long delay or lots of packet loss because they do not consider the dynamic network topology changes caused by human posture. As alternative scheme for dynamic topology, M-ATTEMPT [8] has been proposed to address the dynamic network topology changes in WBAN. In M-ATTEMP, the tree is constructed according to a node's joining or departure whenever a person changes his/her gesture. Furthermore, in the case that a node's temperature approaches the pre-defined threshold, all nodes prevent its temperature rise by disconnecting all links with neighbor nodes during the next few rounds until the temperature turns normal. However, this approach has a problem because a node's function cannot be performed when a node disconnects all links with neighbor nodes. On the other hand, MTR [9] utilizes the movements of the human body in the routing process. MTR defines two types of nodes: mobile node and static node. The mobile is attached to arms and legs while the static node is fixed body parts with no mobility. When the temperature of all neighboring static nodes exceeds the pre-defined threshold, a mobile node is selected as a next hop in order to forward the data to the sink node directly by adapting store and carry scheme.