## 2 Related Work
The number of communication links is utilized to determine which neighbour is the best. Ref. [15] proposes VCR (Volunteer-initiated Connectivity Restoration). Restoring network connectivity is the responsibility of the failed node's near neighbours. The surrounding nodes are chosen based on their proximity to the failing node. Cascaded motions towards the failing node are limited with this method. In [16] introduces PADRA (Partition Detection and Recovery Algorithm). This approach is used to determine the cut-vertex nodes in advance. This may cause the network to divide, resulting in multiple disconnected networks. Each cut-vertex node's failure state is handled by selecting an appropriate neighbour. The failing node is replaced by the selected neighbour, which prevents the network from breaking up as a result. Replacements lead to a chain reaction of events. It has been proposed by [17] that the CRAFT technique (Connectivity Restoration with Assured Fault Tolerance) be used. The discontinuous area is encircled by a BP (Backbone Polygon) using this technique's approach. Two non-overlapping restoration paths are established between each outer partition, and the BP by deploying low-cost Relay Nodes (RNs). By recommending the novel hybrid algorithm PACR, researchers attempt to close these disparities (Position-Aware protocol for Connectivity Restoration). The idea behind PACR is similar to that of someone who makes a will on their deathbed before passing away. Similar to this, a recovery coordinator is formed when the sensor energy falls below the threshold, and a recovery plan is produced. Cutting down on the time that is essential for failure identification quickens the recovery process. The neighbouring nodes do not move to the exact location of the failing node during the recovery process [18]. In ref. [19] also suggests the HRSRT (hybrid recovery strategy on random terrain) method. The land in the area of concern is divided into equal-sized cells. The weight of a pathway is determined by summing the weights of cells that line the path. Connectivity can be restored using the RTPP (Random Terrain Path Planning) technique. Many different strategies are available for deploying relay nodes because the number of mobile data collectors varies. Reduced data collection and acquisition costs and resources are the primary goals of these algorithms. Survivability-Aware Connectivity Restoration for Wireless Sensor Networks with Mobile Nodes was proposed in [20] by the authors of the paper. One-of-a-kind technology connects data load levels between disconnected sections. Re-connectivity is restored after the discovery of these parts. To connect the AOI to the base stations, the authors of ref. [21] propose a robot-controlled approach. Mobile robots need to find the shortest route possible while still staying connected to the network, and this strategy is designed to accomplish that. The proposed method makes use of two different algorithms. The first algorithm assigns the closest robot to the event area. Finally, a non-connected robot is asked to move to a connected portion with an allotted robot by the programme. A search algorithm is looking for unconnected robots until the network is fully connected. As a result of this algorithm, there are fewer hops between base stations and event zones. The cut vertexes have been established, according to [22]. This method employs two distinct approaches to determining whether a node is critical or not. Nodes critical and noncritical can be identified using two-hop local and connected dominant set (CDS) information. In order for the first algorithm to work, the second one is crucial. Unknown network portions can be found without scanning the entire network using a constrained distributed depth-first search strategy. This approach uses long test bed trials to learn the status of all nodes, and simulation results show that this algorithm can detect all essential nodes with relatively little energy if CDS information is available.