## 2 Related Work  
[PERSON] et al. [36] proposed that achieving QoS between the base station and the remote user equipment (UE) requires resolving many trade-offs regarding signalling overhead, implementation complexity and overall delay. They did not recommend any alternate mechanisms to ensure fault tolerance is maintained in the event of failures while achieving the required level of QoS. [PERSON] [37] presented Machine-Type Communication (MTC) which considers simplification of the channels and interfaces such that the communication system is suitable for NB-IoT and LTE-M-based applications. They did not consider any specific networking topology or failure situations. [PERSON] et al. [38] expressed that MTC created an interest in D2D applications, especially in the automotive sector. They did not consider any specific networking topology or failure situations. According to [PERSON] et al. [39], adding D2D to cellular infrastructure will increase reliability, reduce power usage, and prevent network congestion. They suggested a random-access process that uses broadcast messages to announce the D2D mode of communication so that UEs can directly talk with one another, utilising CSMA with collision avoidance. Yet, the endeavour must consider IoT devices and the various resource limits they impose. The concerns with the distance between the base stations and the equipment on either side of the stations must still be considered. A D2D approach for improving battery life and the accessibility of Cellular IoT (CIoT) deployment was proposed by [PERSON] et al. [40]. With the help of the gathered environmental data, the network oversees and maintains the assignment of the UEs to the devices (remote devices, relays) (e.g., battery level and position). The authors create new signalling behaviour allowing UE attachment, transmission mode (re)configuration, and uplink data delivery. Applying a D2D solution controlled by a core network could address RAN (Radio Access Network) failure issues more effectively. [PERSON] NK [41] proposed an Internet of Things (IoT)-based position-fixing system instead of GPS as they are found to be useful in tracking the daily activities of children, the elderly and vehicle tracking. They proposed a redundancy-based model for improving the fault tolerance of the IOT-based position-fixing system. However, they did not account for alternate communication paths in the event of a failure occurring. [PERSON] et al. [42] presented different metrics for computing the fault tolerance of the IoT network. They also presented [11] a crossbar network topology to connect the clusters to the cluster heads. Moreover, they implemented a method to predict the fault that a device will inject due to the power depletion rate. The devices are isolated before the fault can be injected into the system. Many have proposed algorithms to find the shortest path from a source node to the sink node. [PERSON] et al. [43] presented a complete review of different variants of A*-based search algorithms and opined that the algorithm fails as the sizes of the network increase and dynamically change. [PERSON] et al. [44] presented a review of different variants of random walk algorithms, which are meant to find the shortest path in the network. They proposed that one has to select a variant of the algorithm string for a specific application. The algorithm, as such, does not consider the existence of the loops in the network. [PERSON] et al. [45] presented a comparison of variants of [PERSON]'s algorithm for finding k-simple shortest paths, which is based on the number of deviations that the network contains. However, the need for k-shortest paths rarely arises when pruning the paths is achieved to eliminate the failure paths from the system. [PERSON] et al.