## 6 Performance Analysis
### Features and Comparison  
The proposed LDAP achieved the objectives of the WSN coverage in terms of the number of SNs and its geographical coverage, as well as meeting the long lifetime requirement. Table 1 shows a significant reduction (50%) in data sinks in zone 5 with cellular coverage, and is significantly reduced (81%) in zone 1 with poor cellular coverage. Moreover, other main features of the proposed LDAP are as follows:  
* Unlike the UAV-mounted SNs or multi-hop static WSN, a mobile DS can increase the monitoring area coverage significantly. The proposed LDAP can acquire the sensor data using the mobile DS mounted on an UAV for most of the WARM applications where ground mobility may not be possible. UAV-based mobility is not possible for the SNs with short-range wireless links [1], as described in Section 3, due to the required altitude of the UAV; hence, long-range wireless connectivity is required. Moreover, multi-hop routing used for the traditional WSN may not be suitable for the mobile DS due to the routing complexity of the dynamic network topology. * A mobile data sink is more energy efficient than a mobile sensor node, as the number of DSs is much lower than that of the SNs that would be required to cover the same area being monitored. The energy required to facilitate mobility to the SN or DS depends highly on the type of vehicle (or other means) used is not considered. However, for the same type of mobility, a WSN using a mobile DS requires significantly lower energy compared with the WSN with a mobile SN. For a static SN with a static BS, there is no energy required for mobility; however, it may incur other costs due to the high number of BSs. Unlike image-based data acquisition, WARM applications do not require continuous streaming and the SNs can store data over time. The stored data can be transmitted when a wireless link is established with the DS, and in this way, the SN can acquire sensor data at a rate as high as 1-min intervals and transmit it at 60-min intervals using the proposed LDAP. * In terms of coverage, the number of mobile SNs is reduced compared to the static SNs; however, it may lose data coherence over time, which can be overcome by using static SNs associated with a mobile DS. * Most of the routing optimization, clustering, and cluster head election in the WSN is performed using the residual energy and location of the SNs to keep the energy consumption of the SNs uniform (using a smaller cluster size closer to the DS) over the WSN. However, most of these procedures do not consider the environmental impact on the wireless signal quality, and require high processing resources and energy for the SNs, or use heterogeneous nodes (special nodes with higher energy consumption and capacity). The proposed LDAP can select direct RN-based data transmission, based on the residual energy, RSSI, and SNR of the SNs. Therefore, it is more immune to the environmental impact on the wireless signal quality and can maintain the energy balance among the SNs with very low energy consumption due to its light weight. * Moreover, most of the present cluster-based WSNs use multiple hops for data transfer, which require maintaining a static network topology or a complex routing optimization for any changes of topology due to the relocation of the BS. In contrast, the proposed LDAP does not depend on the network topology, as it uses direct or single-hop data transmission from the SNs to the mobile DS. * Present WSNs require complex clustering and routing algorithms to improve the efficiency of overall energy consumption. The complexity and processing load of this type of algorithm demand an additional resource (such as a high-speed processor and extra memory), which introduces energy overhead and cost. It makes the deployment of the WSN complicated and reduces scalability. On the other hand, the proposed LDAP uses only direct and single-hop data transfer, which is lightweight and suitable for resource-constrained sensor nodes.