Two-Slot Based Model of the IEEE 802.11ah Restricted Access Window with Enabled Transmissions Crossing Slot Boundaries

Recently appeared the IEEE 802.11ah standard has introduced a new channel access mechanism, so-called Restricted Access Window (RAW). This mechanism allows an access point (AP) to reduce contention for the channel in overloaded Wi-Fi networks by limiting the number of stations simultaneously accessing the channel. The 802.11ah AP divides all associated stations into groups and allocates for each group an interval of time, which is called a RAW slot. This paper considers the RAW mechanism with enabled transmissions crossing slot boundaries, which means that a station is allowed to end the current transmission attempt even after a completion of the allocated RAW slot. We present a new mathematical model, which allows estimating throughput and energy consumption with this mechanism, and optimizing performance of RAW.