Dynamic Power Saving Mechanism for Mobile Station in the IEEE 802.16e Systems

In wireless communication system, power saving mechanism is a key issue since the mobile station operates depending on limited power. Hence, the IEEE 802.16e system provides three types of power saving classes (PSC I, PSC II and PSC III) for mobile station (MS) to reduce the power consumption. When the MS is using two or more power saving classes, the MS reduces the power consumption only during time interval that does not overlap with any listening window of active PSC called the unavailability interval. Therefore, in this paper, based on the IEEE 802.16e standard, we propose a dynamic power saving mechanism (DPSM) that increases unavailability interval when the MS is using two or more power saving classes (PSCs). The proposed mechanism adjusts sleep window of PSC I (III) to match the start point of listening window in PSC I (III) with that of listening window in PSC II. By doing so, the MS can reduce the listening time, and can increase the unavailability interval. Through analysis and simulation results, we show that the proposed DPSM can reduce the power consumption of MS with two or more PSCs considerably compared with conventional scheme.