# An Efficient Mobility Model for Improving Transmissions in Multi-UAVs Enabled WSNs
## 5 Performance Evaluations  
The proposed technique relies heavily on, as well as exploits, the movement characteristics of UAV in order to achieve significant gains over the already existing models. The evaluation and testing of the approach are done on a model consisting of the base station, WSN motes and the UAVs serving as relays by using NS-3 (version ns-3.28, NSNAM, Washington, DC, USA) and Matlab (version R2018a Online Licence, MathWorks, Natick, MA, USA). The testing is performed on a 1200 \(\times\) 1200 m\({}^{2}\) area. Table 3 lists the detailed simulation settings for the proposed model. The following parameters are used for the testing of the model:  
1. _Coverage_: Network Coverage is defined as the geographical area covered by the network. In the proposed approach, Coverage is defined as the number of nodes served along the path of the UAV given a certain time interval. 2. _Throughput_: Throughput is defined as the number of successful transmissions over the network. In the proposed approach, average throughput is measured across the network. A throughput variation chart is also presented in order to demonstrate consistency and QoS levels of the proposed approach. 3. _Latency_: Latency is described in terms of propagation delay and serialization delay, where propagation delay is a function of the distance between the nodes and speed of the carrier, and serialization delay is a function of packet size and transmission rate. The amount of data flowing through a network or a network bottleneck can be visualized as the function of latency and directly affects the throughput of the system irrespective of the technology used. 4. _Delay_: Delay is defined as congestion or link unavailability and is generally considered a measure of the amount of time a signal takes from source to destination. The model aims at limiting the delay to a constant factor by facilitating direct communication between UAV and WSN nodes. 5. _Jitter_: The non-deterministic behavior of the network is outlined by jitter. Delay sensitive models are also sensitive to jitters and can be described as the variation in delay. 6. _Packet Delivery Ratio (PDR)_: PDR is defined as the ratio of packets sent to the number of packets successfully delivered. Throughput serves as an effective measure of performance of a node or a section, but PDR addresses the quality of network design that can lead to poor overall throughput. 7. _Data Transferred_: Data transferred is the overall data transferred from source to destination nodes throughout the network. It serves as the metric that estimates data over a given connection during the given time interval. 8. _End To End Delivery (EED)_: End To End Delivery is a parameter that estimates per packet delivery from source to destination. Unlike throughput, which treats the whole model as an entity and calculates the average, the EED is a per packet successful evaluation from source to destination. 9. _Packet Drop_: Packet drop is the measure of the number of unsuccessful transmissions across the network. The packet drop is measured with respect to the number of packets lost in contrast with the number of packets sent. Packet drop can be caused by UAV, not in range or congestion in the network. The frequent broadcasts from the WSN nodes can also result in packet drop. The topological awareness and route calculation of the UAV aims at limiting the packet drop to minimum levels.