A Primer on AP Power Save in Wi-Fi 8: Overview, Analysis, and Open Challenges

Wi-Fi facilitates the Internet connectivity of billions of devices worldwide, making it an indispensable technology for modern life. Wi-Fi networks are becoming significantly denser, making energy consumption and its effects on operational costs and environmental sustainability crucial considerations. Wi-Fi has already introduced several mechanisms to enhance the energy efficiency of non-access point (non-AP) stations (STAs). However, the reduction of energy consumption of APs has never been a priority. Always-on APs operating at their highest capabilities consume significant power, which affects the energy costs of the infrastructure owner, aggravates the environmental impact, and decreases the lifetime of battery-powered APs. IEEE 802.11bn, which will be the basis of Wi-Fi 8, makes a big leap forward by introducing the AP power save (PS) framework. In this article, we describe and analyze the main proposals discussed in the IEEE 802.11bn Task Group (TGbn), such as scheduled power save, (semi-)dynamic power save, and cross-link power save. We also consider other proposals that are being discussed in TGbn, namely the integration of wake-up radios (WuRs) and STA offloading. We then showcase the potential benefits of AP PS in several scenarios, including a deployment of 470 real APs on a university campus. Our numerical analysis reveals that AP power consumption can be decreased on average by up to 28 percent, with further improvement potential. Finally, we outline the open challenges that need to be addressed to optimally integrate AP PS in Wi-Fi and ensure its compatibility with legacy devices.