Improving IEEE 802.11 PSM for smartphones by exploiting Hidden Tail-time

WiFi interface is a significant contributor to battery draining on mobile device such as WiFi smartphone. Since distinguishing between unwanted packet and active packet is not feasible at MAC layer, the power management mechanism is equally affected by unwanted packets (packets with unreachable destination port). In this paper, we propose a probing and discarding scheme. It forces unwanted packet to be delivered through the “Hidden Tail-time” that is an additional awake time immediately before smartphone switches from awake-state to sleep-state. Thus, unwanted packets never affect the PSM mechanism. Our proposed scheme improves power saving by up to 67% under mixed setting of unwanted packet and active packet.