Abstract
In Wireless Sensor Networks (WSNs), sensors transmit collected data to a sink using limited battery power. Deployment in remote or inaccessible areas often necessitates networks that remain operational for long periods. Since replacing batteries in numerous sensors is often unfeasible, extending network lifetime is a primary design goal. This is typically addressed by solving four key design problems: coverage, sink placement/routing, sensor activity scheduling, and data routing. These are usually studied individually, or rarely in combination. Network reliability is also crucial for protecting against attacks or failures, preventing coverage holes and data loss. Unlike most studies, this work addresses all four design problems and network reliability in an integrated manner. We propose strategies such as Single Copy (SC) for single-path data transmission, Double Copy (DC) for multi-copy transmission, and a Hybrid (H) strategy where copying occurs in sensors transmitting to central nodes. Tests under various scenarios reveal that the SC strategy is superior for network lifetime, while the DC strategy excels in reliability. The H strategy provides a balanced performance in both lifetime and reliability. Furthermore, to enable the H strategy to find solutions efficiently in large-scale scenarios, we apply a Lagrangian Heuristic (LH) approach. The Lagrangian subproblem is solved using a Dantzig-Wolfe column generation algorithm and a feasible solution is constructed from the Lagrangian subproblem solution at each step. The performance of this heuristic is demonstrated by comparing its results to those obtained with the Gurobi solver. The results show that the LH method provides higher network lifetime compared to Gurobi, especially for medium and large-scale networks.