Evaluating the Performance of eMTC and NB-IoT for Smart City Applications

摘要

Low power wide area network (LPWAN) is a wireless telecommunication networkthat is designed for interconnecting devices with low bitrate focusing on longrange and power efficiency. In this paper, we study two recent technologiesbuilt from existing Long-Term Evolution (LTE) functionalities: Enhanced machinetype communications (eMTC) and Narrow band internet of things (NB-IoT). Thesetechnologies are designed to coexist with existing LTE infrastructure,spectrum, and devices. We first briefly introduce both systems and then comparetheir performance in terms of energy consumption, latency and scalability. Weintroduce a model for calculating the energy consumption and study the effectof clock drift and propose a method to overcome it. We also propose a model foranalytically evaluating the latency and the maximum number of devices in anetwork. Furthermore, we implement the main functionality of both technologiesand simulate the end-to-end latency and maximum number of devices in adiscrete-event network simulator NS-3. Numerical results show that 8 yearsbattery life time can be achieved by both technologies in a poor coveragescenario and that depending on the coverage conditions and data length, onetechnology consumes less energy than the other. The results also show that eMTCcan serve more devices in a network than NB-IoT, while providing a latency thatis 10 times lower.