# Communication Architecture in Mixed-Reality Simulations of Unmanned Systems
## 9 Conclusions  
The MR simulations are beneficial for the development of multi-vehicular systems, as has been shown in the past by several works including our previous effort on developing UAVs. It is mostly beneficial for the validation of the correct function of complex vehicular systems using high-fidelity testbeds. In this work, we have presented requirements and proposed a design for a communication architecture of MR simulations that allows for the co-existence and interaction of virtual and physical entities within a single multi-vehicle system. Suitable architecture topologies have been proposed, and their advantages and disadvantages for various system configurations have been discussed. Methods of addressing and routing in two different communication networks used in the MR simulations have been presented. The precision aspects of the wireless medium utilization have been addressed, and the method of integration of wireless network simulation capabilities have been described.  
Figure 14: Flight tests with Desert Hawks III.  
Figure 15: Aircraft pilot panel with the integrated advisory system—built-in EFIS Integra, Zaon PCAS with GPS on the flight panel and the rest of the system integrated under the panel.  
The proposed resulting system can be utilized as a high-fidelity network simulator for vehicular systems with implicit mobility models that are given by real trajectories of the vehicles. In particular, this means that the mobility of entities does not have to be modeled in advance, and entities move in real time according to their mission, operator commands, or, eventually, incentives from the environment. Moreover, the MR simulations provide the benefits of high-fidelity field experiments, but at a lower cost and with fewer risks, since some of the entities in the system are virtualized. The herein proposed architecture has been already successfully used for the development and validation of several multi-aircraft systems. To the best of our knowledge, no similar architecture for MR simulations has been presented.  
The experiments were designed to validate the proposed communication architecture and have shown that the communication characteristics of a testbed configuration with hardware entities can be substituted with the characteristics of MR testbeds where some of the entities are modeled. Thus, both configurations can be used without a significant difference and effect on simulation accuracy.  
In future work, we would like to extend the approaches discussed in Section 6. In particular, we aim to consider the adaptation of the dynamic transmit power of the simulation platform's modem and exploit the usage of multiple directional antennas and distribution of large transmissions over time to prevent transmission requests from virtual entities that would collectively exceed the available data rates of the platform's modem.  
The presented work has been supported by the Czech Science Foundation (GACR) under the research project No. 16-24206S, the Ministry of Agriculture of the Czech Republic under the contract No. QJ1520187, and the Technology Agency of the Czech Republic under the project No. TA01030847.  
[PERSON] and [PERSON] designed the proposed architecture and deployed it on real aircraft within the described projects. [PERSON] designed and evaluated the experiments. [PERSON] and [PERSON] wrote the the paper.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} FANET & flying ad-hoc network \\ GCS & ground control station \\ HW & hardware \\ HWE & entity embodied in the physical world \\ MAC & medium access control \\ MANET & mobile ad-hoc network \\ MR & mixed-reality \\ RF & radio-frequency \\ SW & software \\ SWE & virtual entity \\ UAV & unmanned aerial vehicle \\ UAS & unmanned aerial system \\ V2I & vehicle-to-infrastructure \\ V2V & vehicle-to-vehicle \\ VANET & vehicle ad-hoc network \\ \end{tabular}