## 1 Introduction
Although there are some applications of disaster evacuation guidance that are available for smartphones, they assume the frequent use of web services. Due to this assumption, those applications become useless once the communication network is damaged. This unavailability of mobile communication services results in the delay of gaining and forwarding critical information for human lives and necessary goods demanded in the disaster areas. With the characteristics of easy deployment, easy access, and no wires, wireless is a promising solution for setting up temporary communication networks in emergency situations. For example, first responders commonly carry portable devices such as intelligent smart phones, PDAs, walkie-talkies, etc., for rescue tasks. Such portable devices, which are usually named as communication nodes, play important roles in data collecting and transmission relaying. In practice, the heterogeneity of communication nodes are especially acute in terms of their coverage and cost, ranging from traditional radio frequency (RF) front-ends installed on ground vehicles and portable masts to last-generation devices operating from unmanned aerial fleets of drones, helicopters, and airplanes [15]. Furthermore, communicational nodes are used in disaster-affected areas for first responders to establish DAWNs in real time to accomplish rescue tasks until the fixed communication infrastructure becomes available. Such networks, which are also called emergency communication networks (ECNs), consist of heterogeneous nodes that communicate in a mobile fashion using wireless links. One example of such ECNs is described by the perception of hastily formed networks [16; 17] that are built-up using smart phones carried by emergency responders and Emergency Communication Vehicles (ECVs) working at the disaster sites to carry out post-disaster recovery operations. The characteristics of DAWNs are as follows: frequent link breakage, inconsistencies in data rates, incompatibility of resources, the temporary unavailability of needed resources and communications links. Researchers have been focusing on mobility models as well as routing algorithms in DAWNs for the improvement of network performance recently. However, common routing protocols are mainly designed for stable or harsh distributed networks, ignoring the mobility of nodes in DAWNs, especially for ECNs that combine several dynamic communicational nodes. In reality, DAWNs are different from traditional Mobile Ad-hoc Networks (MANETs), as they consist of stationary ECVs that appear as relay stations for emergency information; they are also different from Vehicular ad-hoc networks (VANETs), as nodes in DAWNs are asymmetric in energy supply and transmission coverage. Before deploying DAWNs, the following aspects should be considered. Firstly, DAWNs can be rapidly deployed as substitution for destroyed communication infrastructure. Secondly, both fixed nodes and mobile nodes are used in DAWNs in order to adapt to the disaster scenario. Also, such a combination satisfies the demands of effectiveness. Thirdly, unlike traditional wired and wireless networks, the topology of DAWNs changes frequently, as mobile nodes usually change their positions. Thus, a high transmission delay is needed in such frequently changed networks to avoid a low data transmission rate [16]. Such communication networks can be infrastructure-less with typical mobility patterns and delay tolerance, so it is difficult for decision makers to choose optimal solutions to find next-hop nodes. Motivated by solving the problem of selecting the next-hop node in DAWNs, we mainly make the following contributions in this paper:  
* Characteristics of three types of disasters--earthquake, fire and typhoon--are analyzed. Four criteria for decision making are settled not only from the perspective of the decision-making environment, but also from the perspective of decision objective. * We present a method for next hop selection in DAWNs.