The proliferation of Wireless Sensor Networks (WSNs) has necessitated advances in energy-efficient and highly synchronized communication protocols to support the diverse range of Internet of Things (IoT) applications. This thesis presents a modular framework designed to address the critical challenges of reliable throughput, time synchronization, and energy efficiency in low-power WSNs. The framework leverages LoRa-based hardware to implement a novel Medium Access Control (MAC) protocol that facilitates precise time synchronization and robust data scheduling. Key contributions include the development of a one-shot synchronization mechanism capable of aligning thousands of nodes with sub-microsecond accuracy, a TDMA-based scheduling mechanism, and the implementation of energy-efficient techniques such as Low Power Listening (LPL) and duty cycling. This work not only enhances the performance and reliability of WSNs, but also provides a flexible platform adaptable to various IoT scenarios, including environmental monitoring, power grid monitoring, and real-time location systems.