A framework for multimodal wireless sensor networks

During the last decade, the Wireless Sensor Networks have been considered as a broad solution for Internet of Things (IoT) based systems such as noise and air pollution monitoring systems. These systems should be able to monitor the physical variables regularly and simultaneously, to react immediately upon the occurrence of an emergency, and to report the event and its associated data to an observer, in a reliable and energy-efficient way. Recently, the MultiModal Wireless Sensor Networks (M2WSNs) have been proposed as a solution for monitoring oriented applications with low bandwidth requirements that operate simultaneously under normal circumstances and emergencies. In this paper, we present a reliable and energy-efficiency framework for M2WSNs based on the IoT and the Wake-up Radio paradigms. The framework is implemented in ContikiOS, an open-source operating system for IoT solutions, and its performance is evaluated in hardware in an indoor testbed. The experimental results show that the proposed framework provides better reliability in terms of the event reporting latency and packet delivery ratio. Besides, a significant energy-saving is achieved when considering a broadcast-based wake-up scheme with one communication hop for data transmission and acknowledgment procedures in a multi-hop network, compared to a single-radio approach based on a traditional low-duty-cycling and networking techniques.