Estimation of the Wi-Fi Network Capacity when Using Restricted Access Window with Short Slots

The progress on the Internet of Things brings a challenge of providing communications to a tremendous number of simultaneously connected devices. The more stations are transmitting in a wireless network, the higher is the contention for the channel and the slower is the data transmission. The IEEE 802.11ah standard introduces a Restricted Access Window (RAW) mechanism that allows reducing contention for the channel by reservation of channel time for a predefined group of stations. This study is aimed at estimating the network capacity, i.e., the maximum number of stations in a RAW that allows satisfying the requirements for the reliability and data delivery delay at specified channel timeshare restriction and traffic intensity. To estimate the network capacity, an analytical model for servicing sparse traffic when using a periodic RAW with short slots is developed. The problem of optimizing the parameters of a periodic RAW is solved.