# Performance of Sensor Data Process Offloading on 5G-Enabled UAVs
## 3 Experimental Architecture and Results
### Competing Traffic from Multiple 5G-UAVs  
All previous experiments described the behavior of a 5G-UAV operating alone in a 5G cell. Nonetheless, in public cellular networks, single users rarely appear. Therefore, as  
Figure 8: The downlink latency of the 5G-UAV. Sensor offloading on the same 5G-UAV platform is turned on and off two times.  
Figure 9: Trajectory of the 5G-UAV. Sensor offloading on the same 5G-UAV platform is turned on and off two times.  
described in Section 2.2, the available resources of the considered cell are divided between users. The design of this experiment aims to investigate the behavior of a 5G-UAV that offloads a time-critical operation over a 5G network when traffic from a competing 5G-UAV floods the cell's uplink. The goal here is to observe how the relatively small data rate requirement packets that the 5G-UAV, which runs the time-critical autonomous mission, are affected because of the competing traffic. Note here that, as depicted in Figure 5, the state of the 5G-UAV requires only 0.61% of the cell's uplink capacity, which corresponds to the entire sensor data needed to operate the autonomous mission. At the same time, the competing agent (the competing 5G-UAV) would like to transmit data rates that surpass the cell's uplink capability. The experiment starts with the 5G-UAV that runs the autonomous mission of a circular trajectory. At the time \(t_{s}\), the second agent initializes an offloading operation that requires more than the cell's total uplink capacity. Figure 10 depicts the RTT latency measurement for the control data packets of the autonomous 5G-UAV and Figure 11 illustrates the trajectory of the autonomous 5G-UAV. In Figure 10, it is visible that after the initialization of the competing traffic, a small constant offset appears in the RTT control data packet measurements of the autonomous 5G-UAV. The slightly increased latency is associated with the competing traffic and increased scheduling delays. The reason that the 5G-UAV maintains a reliable behavior in its trajectory even when the 5G cell is overloaded by the raw image data is that the 5G network uses a fair scheduler. It is also important to note that for this autonomous mission, the required control data transmission is insignificant compared to the traffic that the second agent requests. Finally, Figure 11 depicts the behavior of the autonomous 5G-UAV, where the accomplished trajectory follows the reference trajectory without any significant error.  
Figure 10: A 5G-UAV’s control data packets RTT when traffic from a competing 5G-UAV begins. A constant offset appears in the RTT latency.  
Ultimately, to conclude, it is evident that to offload a 5G-UAV mission over the cellular network safely, it should be preceded by a meticulous design that describes the communication requirements of the corresponding application. For example, during this experiment, it was observed that the fair 5G scheduling algorithm ensured a fair splitting of the uplink resources that allowed the mission completion without any significant impact on the trajectory or heavily increased latency. However, note that the requirements for the uplink throughput of the UAV that executed the autonomous mission were significantly smaller than for the second UAV (the one that transmitted raw camera data for offloading). Hence, the dynamic throughput as affected by the total cell load and the mobility must be taken into account in the design; otherwise, as depicted in Section 3.3, delays are to be expected in the uplink traffic of the 5G-UAV. We conclude that offloading use cases should consider the dynamic throughput capabilities of the 5G-UAV and include a sufficient safety margin, as indicated in Section 3.2. It is important to note that there are many works available in the literature that deal either with compression mechanisms or offloading policies [11; 13; 14], but to the best of our knowledge, not enough that include into their reasoning the mobility characteristic of the 5G-UAV and the resulting outcomes.