# Communication Architecture in Mixed-Reality Simulations of Unmanned Systems
## 8 Deployment Examples  
The herein described communication architecture has been proposed to enable development and final evaluation with a practical deployment of several multi-vehicle systems (mostly aircraft, i.e., UASs) that used the MR simulations for incremental development and validation. In this section,  
Figure 11: Mean values and standard deviation of data rates of transmissions from neighbors measured at entities (**a**) SWE\({}_{1}\); (**b**) SWE\({}_{2}\); and (**c**) HWE\({}_{3}\) in the MR scenario without the use of the high-fidelity MR architecture when data is sent at a rate of 20 kBps. Figure 12: Scenarios showing the system behavior during message exchange under the presence of a communication obstacle (red). In all cases, each entity tries to send a message to the remaining two. The messages are exchanged only between entities that have mutual obstacle free connectivity (green lines). The rest of the messages are dropped either directly by the effect of the obstacle in the HW scenario or by the network simulation within the GCS in the MR scenario. we describe three particular representative applications to support the benefits of the proposed communication architecture. One of the use cases of the proposed architecture occurred while an unmanned system that provides command and control capabilities over a heterogeneous team of autonomous unmanned aircrafts was being developed [16; 17]. These UAVs are capable of mutual communication and cooperation while they perform complex tactical missions, such as perimeter protection, surveillance, and target tracking. Our system was finally deployed on multiple delta-wing UAVs, see Figure 13.  
Apart from the obvious features, such as the interaction among all of the entities in the simulation, the utilization of the proposed communication architecture provides additional benefits. For example, we were able to measure the requirements of the communication devices used by the UAVs in the MR simulation before purchasing the necessary hardware communication equipment. Further, the features of the message routing and visibility modeling helped us to study the effects of the UAV communication unreachability on the team management in the simulation, which increased the scalability of the whole system. Moreover, using this architecture allowed us to seamlessly move from the pure virtual simulation to the full HW deployment and back according to actual development needs. The second application was to a system for verifying communication-based cooperative collision avoidance methods among multiple fixed wing UAVs. In this case, the objective was to develop a complete testing environment by incrementally deploying the system on two Lockheed Martin's Desert Hawk III aircrafts and training the system operators. An example of the Desert Hawk III launch and field test settings is shown in Figure 14. Here, the communication architecture allowed us to design simulation scenarios with communication requirements similar to those in the case of hardware deployment, and thus allowed us to safely study the effects of communication delays on the developed collision avoidance mechanisms. Further, the proposed architecture allowed for the seamless deployment of the system from the virtual environment to the hardware assets. The operator training process was thus smooth and safe. Finally, the third application was to a system for providing increased flight safety in the domain of light-sport aircrafts, where a combination of existing sensors, negotiation among vehicles, cooperative, and non-cooperative methods of collision avoidance and trajectory planning algorithms are utilized to recommend the best collision-free trajectories for pilots or autopilots of such aircrafts [15]. The final deployment of the advisory system on a Tecnam P-2002 Sierra aircraft is shown in Figure 15. In this case, the communication architecture was used to allow for an MR simulation with both the real and virtual aircrafts, and this was very helpful during the development of such a complex system.