# Research Trends in Collaborative Drones
## 2 Distributed Computing with Drones
### Future Research  
The presented approach requires a dedicated infrastructure, which may not be possible in all drone scenarios and applications. For instance, cloud services and edge nodes to assure the mapping of pseudonyms to real identities may not fit amateur drone applications, i.e., mini-quadcopter drones without an Internet connection. Similar issues have been reported in the anonymity literature related to, e.g., Vehicular Ad-hoc Networks (VANET) [14]). In such VANET scenarios, privacy-preserving strategies leverage mix-network ideas that could also be implemented in collaborative drone applications. The use of group schemes [15; 16] can be complemented with the help of privacy zones, in which entry and exit from a zone can force the update of pseudonyms. The approach can also be extended to crowd area scenarios [17], in which swap pseudonym strategies [18] and obfuscation techniques can help increase the level of anonymity between groups of drones. The main limitation of those approaches is the necessity of dedicated infrastructure and human-operator assistance. We envision machine-to-machine communication solutions without the necessity of deploying a cloud infrastructure to access edge computing services. Such future trends can benefit from alternative schemes considered in avionic and maritime contexts. For instance, the authors in [19] propose secure pseudonym schemes for aircraft in which dedicated entities, referred to as trusted registration authorities, oversee assisting aircraft to generate pseudonyms that are evolving. The generation process guarantees irreversible procedures with respect to tracing back a pseudonym to its real identity. Continuous interaction with the operators associated with the trusted authorities may be an important limitation for drone applications. Moreover, data exfiltration from such trusted authorities may reveal the correspondence between pseudonyms and real identities. Future trends can also be inspired by applications in the maritime domain, in which pseudonym strategies have been enforced over marine vessels via traditionally trusted authorities [20]. The main difference is using an infrastructure-free approach, although a persistent connection to the registration authority is still required. Methods such as those proposed in [21] for the secure and anonymous broadcast of identifiers assume a secure communication channel among mobile vehicles. Inspired by the previous ideas, we envision some alternative methodologies to conduct the anonymous collection and dissemination of information reported in this section, but limiting as much as possible the dependence of drones to cloud infrastructure services as those referred to in Figure 1. A decentralized version of the previous approach is depicted in Figure 2. In this new approach, drones create the list of ephemeral identities by themselves. This way, now both drones \(A\) and \(B\) manage their lists of ephemeral identities, broadcasting and expiring them at regular time intervals. When drones such as \(B\) are reported as faulty, they can be sensed and reported to other drones in the neighborhood by using the list of ephemeral identities previously exchanged when they were still behaving correctly. In contrast to the approach illustrated in Figure 1, drones can now request and obtain lists of ephemeral identities and locally check whether or not their neighbors are potentially faulty. Remote cloud and edge services can be used as a redundant resource to store, forward, and broadcast lists of potentially defective drones identified by their ephemeral identities. In some mission-specific applications, a delegation of distributed processing to edge nodes and cloud services leads to assumptions and issues, which are not always possible to solve--for example, in situations where the deployment of dedicated infrastructure and centralization is not possible.