Reservation methods for IIoT traffic in Heterogeneous Wi-Fi Networks: Comparative Study

In Industrial Internet of Things (IIoT) scenarios, Wi-Fi networks must serve both delay-sensitive sensors and high-throughput stations (STAs). Wi-Fi technology offers two channel reservation methods to ensure low delivery delays for sensors. A strict reservation method, such as Restricted Access Window (RAW), reserves the whole service period (SP) only for sensor transmissions but may waste channel time when sensor traffic is sporadic. A softer method, such as Restricted Target Wake Time (R‑TWT), reserves only the beginning of the SP, reducing the impact on network throughput but potentially increasing delay for sensors. In this study, we compare two reservation methods in Wi-Fi networks, using RAW and R-TWT as examples, in a typical IIoT scenario with rare events detectable by sensors and saturated STA traffic, and find the areas of applicability for each of them.