Search and Integration of Nodes in Hybrid Wireless Sensor Networks by Exploring the Connectivity Frontier

Wireless sensor networks (WSNs) often face challenges with the dynamic deployment of sensors in the region of interest (RoI). The random deployment of static nodes in hazardous or large-scale open environments, dropped by airplanes, results in coverage and connectivity issues due to environmental characteristics. These factors lead to partial coverage and clustering of nodes in the RoI, creating isolated regions. One way to address this limitation is by introducing additional static or mobile nodes. However, adding static nodes increases redundancy and deployment costs. Conversely, this article adopts a hybrid WSN (HWSN) that incorporates mobile nodes to search new clusters. The method proposed requires estimating a communication frontier, which represents the range within which communication with mobile nodes is feasible. However, during navigation over the frontier, there is a risk of disconnection due to environmental factors, such as signal attenuation or the need to avoid obstacles, making the reconnection process crucial, considering the cost and capabilities of these nodes. The proposed method manages these losses, avoids obstacles, and effectively searches and integrates nodes. Furthermore, this approach includes the modeling of node deployment that accounts for the influence of wind. Simulations indicate that this method presents similar connectivity and coverage compared to a geometric approach based on the Voronoi diagram (VD) and adds the capability to navigate around obstacles and tolerate momentary communication loss. However, it comes with the tradeoff of increased displacement and time needed to complete the task. Balancing these factors is essential to optimize the performance of the HWSN.