# Energy-Efficient Opportunistic Routing Algorithm for Post-Disaster Mine Internet of Things Networks
Considering a scenario in which the Mine Internet of Things (MIoT) is rescued in the context of a fully mechanized mining face accident, a large number of surviving nodes are randomly scattered in the accident area, and the planar topology is managed via self-organization to re-establish the post-disaster MIoT network based on a wireless multi-hop routing sensor network. These nodes have the ability to perceive and transmit data information. When the source node collects data information regarding the mine disaster, it uses a multi-hop routing data transmission method to forward the data packet to the sink node, thus completing the effective monitoring of the fully mechanized mining face. Unlike normal mining scenarios, the surviving nodes in post-disaster MIoT networks have extremely limited amounts of energy and cannot be replenished in a timely manner. In addition, frequent data transmission after disasters can cause high levels of communication energy consumption, thereby shortening the entire network's lifetime [8]. Due to the collapse and dispersion of objects such as coal blocks, rock masses, and electrical devices, network nodes in the roadway can be damaged or displaced, which causes the topology to become sparse [9]. In addition, the affected roadway environment is highly complex,  
Figure 1: Three-layer architecture of a typical MIoT system. with a non-uniform, layered geological structure that conducts a large amount of signal loss and multipath attenuation. As a result, the high rate of packet loss will lead to the failure of the post-disaster MIoT to ensure the reliable transmission of data. Due to the aforementioned problems, existing wireless network routing protocols cannot be applied well to post-disaster MIoT data transmission. Therefore, an efficient and reliable routing protocol is urgently required for post-disaster MIoT. Opportunity routing (OR) can improve the reliability of data transmission in wireless networks by fully utilizing the broadcasting characteristics of wireless channels and collaboration between forwarding nodes [10]. Initially, OR was designed to meet the communication requirements of ad hoc networks in sparse mobile scenarios. Nowadays, it has become an important technique for data collection and sharing in wireless multi-hop networks. Considering various Quality-of-Service (QoS) requirements for WSNs, a fuzzy-based load-balanced opportunity routing protocol is proposed [11]. In contrast to traditional deterministic wireless network routing protocols, OR does not require the sender to select a specific relay node before data forwarding, but only needs to maintain the candidate forwarding set (CFS). Moreover, OR can effectively address the problem of link unreliability caused by unstable wireless channels, thus reducing packet retransmissions and improving network throughput. In [12], a virtual-range-forwarding-based opportunistic routing is proposed to overcome the unfavorable characteristics of wireless channels. Hence, the OR method can effectively cope with the vulnerability and the intermittent connectivity of the post-disaster MIoT networks. Nevertheless, there are some drawbacks to traditional OR research studies. On the one hand, the selection of routing metrics is relatively single, without considering various attributes of the network comprehensively. On the other hand, these protocols are designed to improve packet delivery success rates by using a large number of duplicate packets while ignoring the high latency problem in the network. In reality, high latency in MIoT scenarios can seriously affect the efficiency of accident rescue work. Different from the terrestrial routing method, there exist the following challenges for opportunistic routing in the post-disaster Mine Internet of Things (MIoT). First, the surviving nodes after the disaster are constrained by the limited power resources.