Guest Editorial: Special Issue on Energy Efficiency for Internet of Things

The number of IoT devices is increasing at a tremendous rate. It is estimated that there already are about 30 billions IoT devices deployed worldwide (more than 3 per person already!) and this number triplicates in only 10 years. These data are not surprising and clearly explained by the continuous development of new interesting solutions based on IoT. IoT-based applications are countless and being deployed in practically all sectors: for industry and agriculture, for the environment, through monitoring and disaster management, for healthcare and wellbeing, for society and resource management in urban environments