# UAV-Based Privacy-Preserved Trustworthy Seamless Service Agility for NextG Cellular Networks
## 2 Related Work
### NextG Users Privacy  
Privacy concept in cellular communication is the protection of users' personal information and access patterns/activities from leakage or exposure. Nevertheless, the cellular communication providers are allowed to share pieces of the users' activity data with third parties to enhance its end users' experience without revealing any personalized information. The NextG networks' highly connected and service-oriented architecture makes preserving the end-users private information more sensitive and tricky, which requires strong privacy policies [31]. Therefore, the 5G introduces stronger data, location, and identity privacy protocols compared to traditional mobile networks.  
Recent research focuses on enhancing the 5G privacy aspects that may be exposed during certain 5G new features [32; 33]. For instance, in [34], the authors proposed SDN-enabled handover and privacy protection through sharing of user-specific security context information among related access points. In [13], the authors proposed a secure service-oriented authentication framework for IoT services in a 5G network where a privacy-preserving slice selection mechanism is introduced to allow fog nodes to select proper network slices.  
The UAVs utilization within the NextG architecture raises a broad range of privacy issues related to UAVs' data collection and retention, which must be addressed. Accordingly, in [35] privacy design recommendations are proposed, including a Privacy by Designapproach that can help ensure that all legitimate interests and objectives are met in a positive-sum. In [36], the authors discuss blockchain-based privacy preservation solutions for 5G-enabled UAV communications.  
In our proposed 5G UAV-based inter-operator service agility model, user privacy is critical and can lead to a possible private information leakage. It is a relatively straightforward tactic to catch a user's International Mobile Subscriber Identity (IMSI) to authenticate a fake user via alternative strategies. One proposed solution assumes roaming agreement between service providers, and hence, instead of authenticating a user based solely on IMSI, a possible consortium blockchain network can be used as a main authenticator [37; 38]. Therefore, the process proposed in [37; 38] has the IMSI acting as the first step for establishing a handshaking process between networks (a.k.a., a roaming pact). Nevertheless, this blockchain network setup solution reduces the authentication and data transfer speed with small sample sizes. A possible solution to this is known as BigChainDB, which promises to solve problems within the fields of throughput, latency, capacity, querying, permissioning, decentralized control, immutability, and creation and movement of assets [39]. In our proposed privacy-friendly inter-operator agility in a cooperative cellular environment, all the user IDs are concealed and not shared with the guest network as well as the supporting UAVs. Furthermore, the only information collected by the supporting UAV is the concealed user ID and an indicator for whether it is a part of the inter-operator service or not. Such operation protects users' private information from leaking through the weakest link (i.e., the UAV).