Conference Paper

Optimal Sampling for State Change Detection with Application to the Control of Sleep Mode

Maestro Group, INRIA, Sophia Antipolis, France
DOI: 10.1109/CDC.2009.5400669 Conference: Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on
Source: IEEE Xplore


This work considers systems with inactivity periods of unknown duration. We study the question of scheduling ¿waking up¿ instants in which a server can check whether the inactivity period is over. There is a cost proportional to the delay from the moment the inactivity period ends until the server discovers it, a (small) running cost while the server is away and also a cost for waking up. As an application to the problem, we consider the energy management in WiMax where inactive mobiles reduce their energy consumption by entering a sleep mode. Various standards exist which impose specific waking-up scheduling policies at wireless devices. We check these and identify optimal policies under various statistical assumptions. We show that periodic fixed vacation durations are optimal and derive the optimal period. We show that this structure does not hold for other inactivity distributions but manage to obtain some suboptimal solutions which perform strictly better than the periodic ones. We finally obtain structural properties for optimal policies for the case of arbitrary distribution of inactivity periods.

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    • "As heavy-tailed distributed random variables can be well approximated by hyper-exponential distributions [16], [19], this gives motivation to study off-times with hyper-exponential distributions. In [20] we modeled the arrival process as an hyper-exponential process to investigate sleep mode. "
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    ABSTRACT: We consider a mobile connected to a base station, and study how to optimally schedule shutting off its transceiver. First, we study the model from optimal control perspective. We consider off-times (periods of inactivity) of (controlled) duration. We study the question of scheduling "waking up" instants in which the mobile communicates with the base station and checks whether the inactivity period is over. There is a cost proportional to the delay from the moment the off-time ends until the mobile discovers it, a (small) running cost while the mobile is sleeping and a cost for waking up. We present conditions for optimal sleep periods to be constant and derive the optimal period. For the case that the conditions do not hold, we obtain suboptimal solutions which perform strictly better than the optimal constant one. We then investigate optimality restricted to classes of policies with specific constraints. We adopt the parametric optimization approach which entails cost minimization for a given parameterized policy and selection of the best policy among a class. We then compare the performance of optimal policies, of the proposed suboptimal policies as well as that of standard policies like IEEE 802.16e.
    Preview · Article · Sep 2011 · IEEE Journal on Selected Areas in Communications
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    • "By following the traffic dynamics, such a heuristic algorithm reduces the number of sleep-wake actions and hereby avoids energy waste. The latest research from A.P. Azad et al [8], however, presents an important conclusion that for Poisson arrival process, the optimal sleep interval towards the minimal energy consumption should be fixed as a function of the arrival rate. Their work proposes much insight in dealing with PS mechanisms under independent arrival as well as heavy-tailed arrival cases. "
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    ABSTRACT: Power saving (PS) focused on IEEE 802.16 wireless metropolitan area network (WMAN) has been intensively investigated from both theoretical point and perspective of design and implement. Though the IEEE standard of 802.16e leaves room for flexibly designing, we found that dozens of studies set their focus on mechanism improvement, yet seldom considered when those optimized PS mechanisms might, or should be, applicable in their ways. In other words, for practical reasons, if we have to consider the overhead caused by PS itself, then under what conditions should we launch PS mode smartly and unhesitatingly while under others we had better just remain the communication in normal mode? In this paper, we try to discuss this problem via Rent-to-Buy, a widely adopted model in financial sector, and find the criteria that when to get PS launched for the optimal performance. We accordingly propose dynamic strategies for PS, which show significant performance gains in comparison with static strategies and non strategy case.
    Full-text · Conference Paper · Sep 2010
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    • "This study shows us the general cases including the halving mode, and discusses the possibility and performance of designing mechanisms not compatible with the standard. The solid theoretical study in [16] has proved a very important conclusion that, for the Poisson arrival, the optimal window should be fixed as a function of the arrival rate. This result is so important that a number of research directions are thus given, for example, on the one hand one should improve the accuracy of the estimated arrival rate, or to predict it; on the other hand, class II-liked mechanisms using fixed-length of window may deserve more attention in the case of Poisson arrival. "
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    ABSTRACT: This paper considers making balance on the tradeoff between power consumption and extra delay in WiMAX Power Saving. Though it seems quite well understood in case of Poisson traffic, the tradeoff between energy and delay has not been adequately studied in existing literature. We therefore investigate in this work to propose a mechanism of tuning the tradeoff such that users/applications can make their choices to get various QoS requirements satisfied. In this paper, we introduce a new Dual-Threshold mechanism which is derived from Markov analysis. Our mechanism is able to offer different energy and delay performance by moving the initial windows according to the pre-defined best performance thresholds. Through extensive simulations, we've both verified the correctness of the analysis and the effectiveness of the mechanism. Result shows that it has a superior performance in comparison with other existing ones under the assumption of Poisson arrival. Besides, the dual-threshold mechanism is designed fully with standard-compatibility, which indicates that it can be easily adopted in reality.
    Full-text · Conference Paper · Aug 2010
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