Coexistence of Synchronous and Asynchronous MAC Protocols for Wireless IoT Systems in Sub-Gigaherz Band

Recently, the sub-gigahertz band (e.g. 920 MHz in Japan) has been extensively used for the wireless Internet of Things (IoT) because of its advantages such as excellent radio wave reachability, less interference, and many developments and implementations of large-scale wireless multi-hop networks by using interference avoidance technologies such as the media access control (MAC) protocol and frequency hopping. There are two types of the wireless communication systems for IoT: Wi-SUN FAN, as an asynchronous wireless system, and MAC protocol with time-slotted channel hopping (TSCH), as a synchronous wireless system. Wi-SUN FAN and TSCH systems have already been commercialized and installed to the several IoT environments and are expected to expand in scale in the future. Since both systems are operated in the same frequency band of the sub-gigahertz band, the intersystem interference is a concern for the coexistence of systems. In this paper, the possibility of the coexistence between the systems is examined. The intrasystem and intersystem interferences are evaluated by computer simulations in the case of operating the two systems by themselves and that of operating the systems simultaneously in the same frequency channel.