## 2 Related Works  
In recent times, considering thermal-effect on human body as one of the striking criteria, a series of communication protocols have been developed [4, 16, 17, 18]. The proposed protocols consider node temperature as a primary metric for routing decisions. The main objective of the protocols is to maintain the temperature below some threshold and lower the temperature rise rate to avoid significant damage on human body tissue. TARA [4] is one of the primitive protocols in this series. TARA forwards data packets based on localized temperature information and hop-count to the destination. It measures temperature considering heat generation due to radiation from antenna as well as power dissipation due to sensor circuitry. TARA maintains a neighbor table by exchanging neighborhood information, and forwarder node is selected based on the minimal temperature criteria. TARA estimates the temperature rise of its neighbors by listening to the neighbor activities and counting the number of packet transmission and reception. A hotspot is identified if the estimated temperature exceeds a certain threshold. TARA avoids the hotspot(s) by establishing an alternative route toward the destination using a withdrawal strategy where a packet is sent back to its previous sender if all the neighbors are identified as hotspots. The sender then attempts to select alternate route to detour the hotspot(s). After cooling the temperature beneath some threshold, those hotspots can be considered for later routing. Due to the withdrawal strategy, TARA suffers from high end-to-end delay, lower reliability, as well as high energy consumption since the packet needs to traverse many hops when it encounters a hotspot and will be detoured arbitrarily. In order to address the problems of TARA, [PERSON] and [PERSON] [16] proposed LTR. LTR also exploits greedy localized routing approach, where \"coolest\" neighbor is always chosen for data forwarding. To prevent a packet traversing unnecessarily with a large number of hops, a threshold parameter \(MAX\_HOPS\) is defined, and if the hop-count of a packet exceeds the \(MAX\_HOPS\), then the packet is discarded. To avoid the routing loop, each packet maintains a small list of nodes which it has most recently visited and if the \"coolest\" neighbor is already in the list it is ignored to be as a forwarder and the second coolest neighbor is chosen. Because of the greedy approach, a packet in LTR is not always directed to the destination which significantly increases the hop count, thus resulting higher delay and lower reliability. In the same study, the authors presents ALTR, a variant of LTR, with an intent to minimize the packet delivery delay. In ALTR, a packet is forwarded similar to LTR until the hop-count of the packet reaches a threshold, \(MAX\_HOPS\_ADAPTIVE\). However, a shortest path routing algorithm is used if the hop-count value exceeds the threshold. Although, compared to LTR, ALTR optimizes the end-to-end delay to some extent, but it wastes network bandwidth through unnecessary transmissions until the hop count reaches the threshold value. ALTR also allows a packet to traverse through hotspot(s) while utilizing the shortest hop routing. HPR [18], as proposed by the same researchers of LTR and ALTR, follows an opposite mechanism as explained in ALTR. In HPR, a node usually forwards the packets using shortest hop routing. However, it chooses the \"coolest\" neighbor if it encounters a hotspot in the shortest hop-count path. Because of following the same routing strategy upon hop-count detection, HPR also behaves the same as LTR in terms of energy consumption, packet delivery delay and reliability. LTRT [17] has been proposed to address the problems of LTR and ALTR. LTRT requires the knowledge of global network topology where a least temperature route is chosen from all possible routes from a sender node to a destination exploiting the [PERSON]'s algorithm. LTRT, however, incurs much protocol overhead due to its dependency on end-to-end information.