论文标题

物联网中信息时代的风险意识优化

Risk-Aware Optimization of Age of Information in the Internet of Things

论文作者

Zhou, Bo, Saad, Walid, Bennis, Mehdi, Popovski, Petar

论文摘要

最小化信息时代的期望值(AOI)是一种风险中性方法,因此无法捕获具有潜在较大AOI的罕见但至关重要的事件。为了捕获这些事件的效果,在本文中,提出条件价值(CVAR)的概念是一种有效的连贯风险措施,适合最大程度地减少AOI以实时IoT状态更新。在考虑的监视系统中,IoT设备会监视物理过程,并将状态更新发送给具有更新成本的远程接收器。最佳状态更新过程旨在将接收器的AOI,接收器的AOI CVAR和能源成本共同最大程度地减少。此随机优化问题被提出为无限的地平线折扣风险感知的马尔可夫决策过程(MDP),由于CVAR的时间不一致,这在计算上是棘手的。通过利用相干风险度量的特殊特性,将风险感知的MDP降低到具有增强状态空间的标准MDP,我们使用动态编程来得出最佳的平稳策略。特别是,风险意识的MDP的最佳历史依赖性政策仅通过增强系统状态才能取决于历史,并且可以使用增强的MDP的最佳平稳政策轻松构建。所提出的解决方案显示出可以在计算上进行的处理,并能够以风险感知的方式在实时IoT监视系统中最小化AOI。

Minimization of the expected value of age of information (AoI) is a risk-neutral approach, and it thus cannot capture rare, yet critical, events with potentially large AoI. In order to capture the effect of these events, in this paper, the notion of conditional value-at-risk (CVaR) is proposed as an effective coherent risk measure that is suitable for minimization of AoI for real-time IoT status updates. In the considered monitoring system, an IoT device monitors a physical process and sends the status updates to a remote receiver with an updating cost. The optimal status update process is designed to jointly minimize the AoI at the receiver, the CVaR of the AoI at the receiver, and the energy cost. This stochastic optimization problem is formulated as an infinite horizon discounted risk-aware Markov decision process (MDP), which is computationally intractable due to the time inconsistency of the CVaR. By exploiting the special properties of coherent risk measures, the risk-aware MDP is reduced to a standard MDP with an augmented state space, for which we derive the optimal stationary policy using dynamic programming. In particular, the optimal history-dependent policy of the risk-aware MDP is shown to depend on the history only through the augmented system states and can be readily constructed using the optimal stationary policy of the augmented MDP. The proposed solution is shown to be computationally tractable and able to minimize the AoI in real-time IoT monitoring systems in a risk-aware manner.

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