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An adaptive PSM mechanism in WLAN based on traffic awareness

Wireless devices consume large amount of energy during wireless communication. Since the energy storage of battery is limited, improving energy efficiency has become an important approach to prolong the lifetime of device. IEEE 802.11 protocol supports power save mode (PSM) in wireless local area networks (WLANs). But the standard PSM cannot adapt to the changes of traffic load or channel conditions. Therefore, this paper proposes an adaptive PSM mechanism (APSM) which improves energy efficiency of wireless devices in a WLAN with access point (AP). According to the current channel condition and traffic load, the AP gives devices with different priorities when they fetch buffered packets. The devices can adaptively adjust listening intervals according to network traffic and adopt different congestion windows when the network topology changes. APSM has been implemented and evaluated in NS-2. The simulation results have shown that the device using APSM can save 58% energy at most compared with the one using the standard PSM.