Browsing by Author "Wang, Shiou-Wen"

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Per-flow sleep scheduling for power management in IEEE 802.16 wireless networks
(2011-11-10)
Chen, Jen-Jee
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Wu, Shih-Lin
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Wang, Shiou-Wen
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Tseng, Yu-Chee
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資訊工程學系
Power management is a critical issue in IEEE 802.16 wireless networks. In the standard, a power saving class (PSC) of type II is defined to support real-time traffic flows. It allows a flow to switch periodically between active and sleep states to save energy. However, previous studies either consider adjusting start frames of PSCs by assuming that the PSCs are already given or assume one single PSC to accommodate all flows in a mobile station, thus leading to higher energy cost. This paper proposes two "per-flow" sleep scheduling schemes, which assign one PSC to each real-time flow according to its QoS parameters. This leads to less energy consumption, more efficient use of bandwidth, and more compact listening windows. We also prove that deciding whether a given scheduling problem is solvable can be reduced to a maximum matching problem, which is computationally tractable. Simulation results show that such a per-flow scheduling does perform much closer to the active ratio lower bound and achieve higher resource utilization than previous schemes. (C) 2011 Elsevier B.V. All rights reserved.
Power Saving Class Management for Energy Saving in IEEE 802.16e Wireless Networks
(2009)
Chen, Jen-Jee
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Wu, Shih-Lin
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Wang, Shiou-Wen
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資訊工程學系
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Department of Computer Science
Power saving is a critical issue in the IEEE 802.16e broadband wireless networks. In order to reduce the power consumption, the IEEE 802.16e provides three types of power saving classes (PSCs) for the Mobile Subscriber Stations (MSSs), where each PSC may contain one or several connections. However, how to define a PSC and assign PSCs to connections are open issues in the standard. Focusing on real-time traffics, a single MSS and base station (BS) pair, previous studies use a single PSC of type II to manage the awake and sleep of the MSS. In this paper, two power saving class management algorithms based on multiple PSCs in the IEEE 802.16e are proposed. These two schemes define PSCs for real-time connections by referring to the delay bound and packet interarrival time of connections. Simulation results demonstrate that our schemes outperform the previous single PSC approach in both energy efficiency and resource utilization.