论文标题
模型预测性控制,用于具有不同拓扑的离散时间排队网络
Model-Predictive Control for Discrete-Time Queueing Networks with Varying Topology
论文作者
论文摘要
在本文中,我们为传统的离散时间排队网络配备了马尔可夫的输入过程,除了通常的短期随机性外,它还控制着网络节点之间链接的长期行为。这让人联想到控制理论中所谓的跳跃马尔可夫系统,并允许网络拓扑随着时间的推移而发生变化。我们认为,常见的后压控制策略不足以控制这种网络动态,并提出了一个受模型预测控制范式启发的新颖控制政策。具体而言,通过定义合适但任意的预测范围,我们的政策考虑了未来的网络状态和可能的控制措施。这与大多数其他近视政策形成鲜明对比,即仅考虑下一个状态。我们在数值上表明,这种方法可以显着改善控制性能并引入多种变体,从而交换性能与计算复杂性。此外,我们证明了我们政策的所谓吞吐量最优性,可确保网络可以维护的所有网络流的稳定性。有趣的是,与模型预测性控制中的一般稳定性证明相反,我们的证明不需要终端集的假设(即预测范围足够大)。最后,我们提供了几个说明示例,其中之一是同步队列网络。特别是这是一个有趣的系统类别,在该类别中,我们的政策比一般的背压策略具有优势,甚至在这些网络中失去了吞吐量的最佳性。
In this paper, we equip the conventional discrete-time queueing network with a Markovian input process, that, in addition to the usual short-term stochastics, governs the mid- to long-term behavior of the links between the network nodes. This is reminiscent of so-called Jump-Markov systems in control theory and allows the network topology to change over time. We argue that the common back-pressure control policy is inadequate to control such network dynamics and propose a novel control policy inspired by the paradigms of model-predictive control. Specifically, by defining a suitable but arbitrary prediction horizon, our policy takes into account the future network states and possible control actions. This stands in clear contrast to most other policies which are myopic, i.e. only consider the next state. We show numerically that such an approach can significantly improve the control performance and introduce several variants, thereby trading off performance versus computational complexity. In addition, we prove so-called throughput optimality of our policy which guarantees stability for all network flows that can be maintained by the network. Interestingly, in contrast to general stability proofs in model-predictive control, our proof does not require the assumption of a terminal set (i.e. for the prediction horizon to be large enough). Finally, we provide several illustrating examples, one of which being a network of synchronized queues. This one in particular constitutes an interesting system class, in which our policy exerts superiority over general back-pressure policies, that even lose their throughput optimality in those networks.