# Connection-Aware Digital Twin for Mobile Adhoc Networks in the 5G Era
## 4 Experimental Results
### Evaluation Setup  
The assessment of the proposal has been conducted in a laboratory context, using four physical smartphones to form the 5G-MANET. Additionally, a laptop is used to execute the DT. The experimental design focuses on evaluating the accuracy of the virtual representation in the DT, analyzing the update time and the accuracy of the calculated performance for the 5G-MANET. As a result, the evaluation scenario considers two main variables: the 5G connection of the nodes in the network and the QoS evaluation.  
On the one hand, the first condition enables the assessment of the context-aware functions, analyzing the impact of routing on the latency of the DT. On the other hand, the comparison between the QoS report calculated by the DT and the one obtained from the physical 5G-MANET assesses the accuracy of the global reports. The considered variables are described below:  
Figure 5: Architecture of the DT in the proof-of-concept.  
- Fixed Online Topology (FOT). This topology consists of a static ring where all nodes are connected to the Internet. In this case, no routing is required to keep the DT updated.
- Fixed Partially-Online Topology (FPOT). The topology follows a ring distribution, where four nodes lack 5G connection and only one is connected to the Internet. As a result, distance-based routing is required to keep the DT updated.
- Dynamic Online Topology (DOT). All nodes are connected to 5G, but the topology is not fixed. Thus, although each node can send control information to the DT, local messages in the MANET still require routing.
- Dynamic Partially-Online Topology (DPOT). This topology is not fixed, so nodes move within the physical context. Additionally, only one device has a 5G connection, so routing is required to keep the DT updated.  
The proposed scenarios are executed using mid-range smartphones, with their positions and connections modified randomly. The movement in the context is performed in an open space of 1000 m\({}^{2}\) (20 m \(\times\) 50 m), allowing for occasional local disconnections between nodes. Finally, the network is run for a period of 15 min. - Accuracy of global performance. Considering that the DT provides QoS reports based on the events reported in the network, four variables are measured for the experiment: delivery probability, latency, overhead, and hop count.  
In addition to the considered metrics, concretely in partially online scenarios, it is relevant to consider the impact of the routing in the resulting QoS. Actually, relying on routing based on opportunistic contacts between nodes in the ad hoc network may drive to additional interchange of data. As a result, these interactions drive an inherent overhead which affects latency. However, their impact on the reports is not significant, since only network events unrelated to overhead processes are monitored and transmitted to the DT,  
Figure 6: Defined topologies to assess the accuracy of the DT.  
including a timestamp for each. As a result, despite the overhead, the DT can perform estimations accurately based on the reports received from the nodes.  
Addressing the described scenario variations, the QoS metrics are analyzed for each executed scenario, comparing the results obtained from the physical network with those provided by the DT. Additionally, the cost of computational complexity is examined by analyzing the consumption of critical resources, such as energy consumption for the mobile nodes and CPU usage for the server executing the DT. Furthermore, a study of the control information shared between nodes in partially online contexts is included. The next subsection analyzes the various statistics obtained and discusses the results.