Real-time Sampling and Estimation on Random Access Channels: Age of Information and Beyond
Real-time Sampling and Estimation on Random Access Channels: Age of Information and Beyond
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DOI：
10.1109/infocom42981.2021.9488702
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
Xingran Chen;Xinyu Liao;S. S. Bidokhti-S.
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文献类型：
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作者：
Xingran Chen;Xinyu Liao;S. S. Bidokhti-S.
在随机接入信道中考虑自回归马尔可夫过程的实时采样和估计。研究了两类政策：（i）不经意的政策，其中决策制定独立于源实现，以及（ii）非不经意的政策，其中对源进行因果观察以进行决策。在第一类中，最小化预期时间平均估计误差相当于最小化预期信息年龄（AoI）。为此类中可实现的估计误差提供了下限和上限，并且基于年龄的阈值策略与最先进的技术相比提供了两倍的改进。在第二类中，提出了基于错误的阈值策略：当发送器的错误超过阈值时，发送器变为活动状态，在这种情况下，发送器按照时隙ALOHA概率进行发送。导出了估计误差的闭合形式表达式，作为峰值寿命、传输延迟（我们称之为静默延迟的术语）以及源实现的函数。通过将底层源视为离散维纳过程来对其进行近似分析。与遗忘策略相比，所提出的阈值策略提供了三倍的改进，并且其性能接近集中式贪婪调度。
Real-time sampling and estimation of autoregressive Markov processes is considered in random access channels. Two classes of policies are studied: (i) oblivious policies in which decision making is independent of the source realizations, and (ii) non-oblivious policies in which sources are observed causally for decision making. In the first class, minimizing the expected time-average estimation error is equivalent to minimizing the expected age of information (AoI). Lower and upper bounds are provided for the achievable estimation error in this class and age-based threshold policies are shown to provide a two-fold improvement compared to the state-of-the-art. In the second class, an error-based threshold policy is proposed: a transmitter becomes active when its error exceeds a threshold in which case it transmits probabilistically following slotted ALOHA. A closed-form expression is derived for the estimation error as a function of the peak age, the transmission delay, a term which we call the silence delay, as well as the source realization. It is analyzed approximately by considering the underlying source as a discretized Wiener process. The proposed threshold policy provides a three-fold improvement compared to oblivious policies and its performance is close to that of centralized greedy scheduling.