Mathematical Models of Modern Power Save Mechanisms in Wi-Fi Networks

Abstract—

The Wi-Fi standard describes a number of power save mechanisms, the main idea of which is to periodically turn off the radio to save energy on channel listening. In modern Wi-Fi networks, such mechanisms include Target Wake Time (TWT) and Wake-Up Radio (WUR). Despite the fundamental differences between these mechanisms, they both use the activity period scheduling alternating with long intervals of turning off the main radio. Turning off the main radio not only saves energy, but also causes the loss of synchronization between the clocks of the power-saving stations with the access point clock because of the clock drift effect, which can negatively affect the efficiency of these mechanisms. In this paper, mathematical models of frame transmission from an access point to power-saving stations using TWT and WUR have been developed. The models consider the clock drift effect and allow us to evaluate the efficiency of the considered mechanisms in terms of average power consumption and average frame delivery delay.