## 3 Related Work  
Authentication in 5G network covers heterogeneous devices and networks considering the systematic requirements in terms of Availability, Flexibility, and Auditability. For this, [PERSON] et al. [26] proposed a framework that allows nodes to select proper network slice for anonymous data communication and grant authentication of users to IoT servers using service-oriented authentication and key agreement supporting network slicing and fog computing for 5G enabled IoT. [PERSON] et al. [15] introduced a concept of Kerberos Authentication server. Their approach aims to provide a fast and efficient authentication service at cloud computing that was significantly threatened by the DDoS attacks. Kerberos is designed for authentication of service to secure communication between authorized mobile devices and cloud server in 5G network. [PERSON] et al. [13] focused on offloading both the computation and communication energy on the Mobile Edge Computing server in the 5G network by solving the optimization problem and designing an energy-efficient MEC cloud offloading resource allocation schemes in the 5G heterogeneous network. [PERSON] et al. [27] designed a new secure key management and user authentication scheme called SAKA-FC for fog computing, and their proposal uses lightweight operations for smart devices as they are resource-constrained by nature. Furthermore, [PERSON] et al. [28] presented a new REconfigurable Solution for IoT security ReSIoT by using a group signature to practice anonymous authentication by signing a given message as a group-based public key credential among the connected devices based on the 5G Edge network. In [PERSON] et al. [24] presented the TrustZone architecture to enhance the 5G AAA with cognitive access management, the authors designed a context-aware mechanism of synchronizing subscriber authentication information to local subscriber databases, thus reducing the backhaul network traffic generated by TrustZone and improving the authentication process in 5G. [PERSON] et al. [23] discussed multiple security challenges in Mobile Edge Caching MEC, which are used in 5G by Mobile Edge Computing to reduce the computation overhead and latency. MEC is vulnerable to attacks like Jamming attacks, DoS, Spoofing attacks, to solve this problem, the authors proposed a security solution based on reinforcement learning such as RL(Reinforcement Learning)-based Anti-Jamming, RL-based Authentication. Their proposal can enhance the security and user privacy of mobile edge caching systems, thus having a reliable 5G network. While the authors of [12] discussed the value of MEC as a standardized solution for Edge Computing especially for use cases targeting fully connected cars, however, these cases require the fulfillment of challenging requirements, which are only possible with the use of 5G networks. The following Table 1 shows the considerations of related works. As mentioned in Section 2, the authentication mechanism needs to consider four considerations: availability, flexibility, auditability, and independence on authentication authority. However, independence on authentication authority has not discussed to cover the heterogeneous network of 5G because secondary authentication is not standardized yet. Therefore, we propose an efficient secondary authentication frameworkconsidering edge and fog computing architecture.