Abstract
Nowadays, the current trend in research is going towards the combination of the Cloud and Internet of Things. This interplay is referred to as Cloud of Things (CoT). CoT aimed to provide pervasive and ubiquitous computing, in which IoT capabilities are provisioned as services (e.g., sensing as a service) in an on-demand fashion. However, smart services that characterized as real-time and delay-sensitive require energy efficient CoT architectures. This paper surveys CoT architectures, platforms and the application of CoT in the context of healthcare. Moreover, the paper mainly emphasizes on investigating and discussing the most relevant energy efficiency proposals. The investigation of such works reveals that further efforts are still required to obtain energy-efficient CoT architectures, particularly in healthcare, in which the tradeoffs between energy efficiency, delay, and quality of service is considered.