Scheduling Problems in Wireless Sensor Networks and Internet of Things: A Comparative Overview

With limited power levels of communication devices, minimizing communication latency is a critical and practical problem in communication networks as it targets to reduce energy consumption thereby prolonging networks' overall lifetime. Particularly, the minimum latency problem for Wireless Sensor Networks (WSNs) has been studied extensively. Also, some approaches for WSNs have been applied to IoTs, considering WSNs to be identical to Internet of Things (IoTs), which is a misnomer. As WSNs are special cases (subsets) of IoTs, existing approaches for specific WSNs can address only the corresponding special cases. Therefore, it is desirable to design optimization algorithms that can adapt not only special cases, but also more general and realistic IoT environments. We discuss the distinction between WSNs and IoTs, and show that the widely used conventional antenna and interference models for WSNs cannot be directly applicable to the general IoTs. Also, we establish new antenna and interference models that opt for IoTs. Furthermore, we comparatively overview and discuss the problems of minimizing latencies of schedules in WSNs and IoTs for four group communication patterns, namely broadcasting, gossiping, data collection, and aggregation. Finally, we conclude with the future research directions.