Low Power Wide Area Networks (LPWANs) for Internet of Things (IoT)   Applications: Research Challenges and Future Trends
  Internet of things (IoT) changes significantly the requirements for connectivity, mainly with regards to long battery life, low device cost, low deployment cost, extended coverage and support for a massive number of devices. Driven from these requirements, several different cellular and non-cellular low power wide area network (LPWAN) solutions are emerging and competing for IoT business and the overall connectivity market. Motivated by this, in this paper, we review and compare the design specifications of different LPWAN solutions, as well as, we discuss their suitability for different IoT applications. Finally, we present the challenges, future trends, and potential research directions for LPWANs. 
Alexandros-Apostolos A. Boulogeorgos, Panagiotis D. Diamantoulakis,   George K. Karagiannidis
cs.NI