Optimizing Sampling for Data Freshness: Unreliable Transmissions with Random Two-way Delay
Optimizing Sampling for Data Freshness: Unreliable Transmissions with Random Two-way Delay
复制标题
DOI：
10.1109/infocom48880.2022.9796895
复制
发表时间：
2022-05
期刊：
影响因子：
--
通讯作者：
Jiayu Pan;A. Bedewy;Yin Sun;N. Shroff
中科院分区：
文献类型：
--
作者：
Jiayu Pan;A. Bedewy;Yin Sun;N. Shroff
在本文中，我们研究了一个采样问题，其中一个信号（源）的新鲜样本通过一个不可靠的信道发送到一个远程估计器，并通过一个反馈信道发送回的信号。前向和反馈信道都受到随机传输时间的影响。受分布式传感的启发，估计器可以通过组合通过信道接收的信号样本和从本地传感器收集的噪声信号观测来估计源信号的实时值。我们证明了估计误差是一个非减函数的年龄的信息（AoI）接收信号样本和设计的最佳采样策略，最大限度地减少了长期的平均估计误差。最佳采样器设计遵循阈值策略：如果最后一次传输成功，则源等待，直到交付时的预期估计误差超过阈值，然后发送新样本。如果最后一次传输失败，源立即发送一个新的样本，而无需等待。阈值是定点方程的唯一根，并且可以以低复杂度求解（例如，通过对分搜索）。此外，所提出的采样策略也是最佳的最小化的AoI的一般非减函数的长期平均值。它的最优性适用于一般的前向和反馈信道的传输时间分布。
In this paper, we study a sampling problem in which fresh samples of a signal (source) are sent through an unreliable channel to a remote estimator, and acknowledgments are sent back over a feedback channel. Both the forward and feedback channels are subject to random transmission times. Motivated by distributed sensing, the estimator can estimate the real-time value of the source signal by combining the signal samples received through the channel and noisy signal observations collected from a local sensor. We prove that the estimation error is a non-decreasing function of the Age of Information (AoI) for received signal samples and design an optimal sampling strategy that minimizes the long-term average estimation error. The optimal sampler design follows a threshold strategy: If the last transmission was successful, the source waits until the expected estimation error upon delivery exceeds a threshold and then sends out a new sample. If the last transmission fails, the source immediately sends out a new sample without waiting. The threshold is the unique root of a fixed-point equation and can be solved with low complexity (e.g., by bisection search). In addition, the proposed sampling strategy is also optimal for minimizing the long-term average of general non-decreasing functions of the AoI. Its optimality holds for general transmission time distributions of the forward and feedback channels.