A Practical PSM Scheme for Varying Server Delay

Today, many individuals use smartphones or other battery-powered mobile devices equipped with Wi-Fi to access the Internet. Since the network interface cards (NICs) often use a substantial portion of available energy, schemes such as the 802.11 power saving mode (PSM) have been used to limit the amount of time a NIC is awake in an operable state so as to extend battery life. However, since the NIC cannot retrieve packets while sleeping, PSM may negatively impact packet delay. These delays are also unbounded and can significantly increase communication time, particularly in a mobile environment where server delays may change drastically. To mitigate this, we present PSM-AW: a PSM with adaptive wake-up. PSM-AW is a client-side solution that allows the client device to sleep for a maximum time interval while still keeping a tight bound on performance. We present and prove a bound on performance using PSM-AW and demonstrate its effectiveness through extensive simulations and experiments.