## 2 Related Works
In [15; 16] introduce this routing structure, where nodes use geographic routing to send packets to the nearest ring node and obtain the location of the sink; however,this ring structure may introduce high latency. To solve this problem, in [17], the authors create multiple rings and update the sink's location only to the nodes on the rings, thus reducing the network latency. Furthermore, in [18], the authors propose novel harvested energy scavenging and transfer capabilities in an opportunistic ring routing protocol, which comprehensively enhances the performance of the network and improves the high latency defects of ring routing; however, due to the high traffic around the ring routing structure, nodes near the ring are more likely to die and the energy consumption of the network is not balanced enough. The grid structure is an energy-efficient network structure studied by scholars in recent years. In [19], researchers propose a routing protocol based on mode-switched networks, where a node is selected as a grid head in a divided grid, and the source node's data transmission is accomplished by forwarding through the grid head, which improves the network lifetime to a great extent. Literature [20] comes up with a routing protocol based on a virtual grid structure, which uses the network structure to select specific nodes to save the location of the sink and share the information with common nodes, effectively reducing the network energy consumption and delay. In [21], the authors put forward a novel heuristic trust scheme that greatly improves the security and communication quality of the network, but this approach does not support mobile sinks. It is necessary to make the sink move, a mobile sink can alleviate the hotspot problem to some extent and prolong the network lifetime. The use of a tree-based data dissemination model for mobile sinks greatly improves the network lifetime and reduces the network energy consumption in [22; 23], but some nodes will go through longer paths for transmitting data back to the sink, which may lead to higher latency. In [24], the authors develop an energy-efficient routing protocol for large-scale I-IoT networks in a cloud-based SDN system and plan the optimal mobility paths for mobile sinks which effectively reduces the network energy consumption and latency, but with a low packet delivery rate. In [25], in order to solve the problems of unreliable data transmission (data transmission is trapped in an infinite loop) and routing hotspots in a standard geographic routing protocol, the authors put forward routing based on tree and geographic protocol (RTG), the algorithm divides the network into outer and inner areas, and the two areas use the improved geographic routing protocol and tree-based routing protocol, respectively, which balances the energy consumption of the network, and greatly improves the network lifetime, throughput, and delay, but the random mobility of the sink may lead to poorer network performance. The autonomous mobile sink based on the geographic routing protocol (AMSG) [26] further improves the network lifetime and throughput by allowing the sink to move autonomously based on RTG; however, due to the blindness of the geographic routing protocol, its packet delivery rate is not high. Apart from data transmission in routing protocols, the coverage problem of WSN has also been a hot research topic. In [27; 28; 29; 30] machine learning as well as approximation algorithms for optimization of disk-based coverage control are combined; the coverage of the network is improved and the network resources are fully utilized. However, the sensor nodes are required to be able to move, which increases the cost and is not applicable to large-scale networks. In addition, these studies are conducted on the traditional disk coverage, when the sensing point is outside the disk coverage, such data often cannot be collected; they do not take into account the collaborative work between the nodes. Finally, these coverage algorithms do not consider data connectivity.