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

Development of the Internet of Things (IoT) requires provision of communications to a large number of devices simultaneously connected to a network. The growth of the number of simultaneously connected stations results in higher contention for the channel and slowing down of data transmission. The IEEE 802.11ah standard introduces a Restricted Access Window (RAW) mechanism that allows reducing the contention for the channel by reserving channel time for a predefined group of stations. The goal of this study is to estimate the network capacity, i.e., the maximum number of stations that transmit within the RAW, for which the requirements for data delivery reliability and delay for predefined restrictions on channel resource and frame generation rate can be fulfilled. To estimate the network capacity, an analytical model of transmitting sparse data traffic using a periodic RAW with short slots has been developed. The problem of optimizing parameters of the periodic RAW mechanism is solved.