## 2 Related Work
MTR uses routing cost \(P\) that is calculated by multiplying pre-defined weighted factor and connection time between a source node and a mobile node. It is to prevent the data loss caused by movement of the mobile node. Figure 2 illustrates the routing process in MTR. If source node A is surrounded by hot spots, node A forwards the packet to mobile node B, and then node B stores the packet in its buffer until it is connected to the sink. Otherwise, all packets from node A are forwarded to a static node with lowest temperature. However, the store and carry scheme has a drawback in that the emergency sensor data may be delayed if it is delivered by a mobile node. To solve this problem, FTAR has been proposed. FTAR is a forwarder based temperature-aware routing protocol that supports multiple traffic transmission. FTAR categorizes the data into normal and critical data. In order to forward normal data, each source nodes select a mobile node which is the most likely to be connected to the sink as a forwarder. To select a forwarder among neighboring mobile nodes, FTAR uses \(Total\ Connected\ Time\ (TCT)\) which means duration time in which a mobile node was connected to the sink. However, if there are no mobile nodes, normal data is forwarded to the node with the lowest temperature. On the other hand, critical data is forwarded to the node with  
Figure 1: Next hop selection in the two hops ahead algorithm. Figure 2: Next hop selection in Mobility and Temperature-aware Routing (MTR). the smallest number of hops in order to reduce the end-to-end delay. Similarly, MTARP [10] selects the best next hop while considering three metrics such as hop count, temperature, link quality at the same time. The hop count denotes the number of hops to the sink while the temperature is the temperature of a neighbor node. Moreover, the link quality represents the signal power received from a neighbor node. These metrics are used to compute link cost between a source node and a neighbor node at time t. However, since the link cost is simply calculated by multiplying the metrics and pre-defined weighted factor, the impact of these factors is not explored well. In addition, these approaches cannot guarantee good performances because they set the highest weight to the hop count metric or exploit a heuristic or constant weighted factor for calculating a routing cost. As a result, they lead to packet loss, long end-to-end delay and average temperature rise in networks. Based on this analysis, a logical approach is required to determine the weight of each metric in a reasonable way because the metrics are not correlated to each other. Other QoS aware routing protocols for WBANs have been proposed in [14; 15; 16; 17]. LAEEBA [14] and CO-LAEEBA [15] were introduced to support reliable transmission and efficient energy consumption by using the multiple metrics such as residual energy and path loss rate. On the other hand, ARBA [16] uses residual energy and bandwidth as routing metrics to enhance bandwidth utilization and network lifetime. [PERSON] et al. [17] provide the energy efficient next hop selection algorithm, and the algorithm uses the hop count and link cost function to satisfy QoS requirements such as lower delay and reliable transmission. To address the above-mentioned limitations, we propose an Enhanced version of MTARP (EMTARP) based on the MCDM method while considering the hop count, temperature and link quality.