College of Information Engineering, Xiangtan University, Xiangtan 411105, China.
Key Laboratory of Intelligent Computing and Information Processing of Education Ministry, Xiangtan University, Xiangtan 411105, China.
Sensors (Basel). 2018 Jul 10;18(7):2223. doi: 10.3390/s18072223.
Wireless Power Transfer (WPT) technology is considered as a promising approach to make Wireless Rechargeable Sensor Network (WRSN) work perpetually. In WRSN, a vehicle exists, termed a mobile charger, which can move close to sensor nodes and charge them wirelessly. Due to the mobile charger's limited traveling distance and speed, not every node that needs to be charged may be serviced in time. Thus, in such scenario, how to make a route plan for the mobile charger to determine which nodes should be charged first is a critical issue related to the network's Quality of Service (QoS). In this paper, we propose a mobile charger's scheduling algorithm to mitigate the data loss of network by considering the node's criticality in connectivity and energy. First, we introduce a novel metric named criticality index to measure node's connectivity contribution, which is computed as a summation of node's neighbor dissimilarity. Furthermore, to reflect the node's charging demand, an indicator called energy criticality is adopted to weight the criticality index, which is a normalized ratio of the node's consumed energy to its total energy. Then, we formulate an optimization problem with the objective of maximizing total weighted criticality indexes of nodes to construct a charging tour, subject to the mobile charger's traveling distance constraint. Due to the NP-hardness of the problem, a heuristic algorithm is proposed to solve it. The heuristic algorithm includes three steps, which is spanning tree growing, tour construction and tour improvement. Finally, we compare the proposed algorithm to the state-of-art scheduling algorithms. The obtained results demonstrate that the proposed algorithm is a promising one.
无线电能传输（WPT）技术被认为是使无线可充电传感器网络（WRSN）永久工作的一种有前途的方法。在 WRSN 中，存在一种称为移动充电器的车辆，它可以移动到靠近传感器节点并对其进行无线充电。由于移动充电器的有限行驶距离和速度，并非每个需要充电的节点都能及时得到服务。因此，在这种情况下，如何为移动充电器制定路线计划以确定应首先为哪些节点充电是与网络服务质量（QoS）相关的关键问题。在本文中，我们提出了一种移动充电器调度算法，通过考虑节点在连接性和能量方面的重要性来减轻网络的数据丢失。首先，我们引入了一个新的度量标准，称为关键指数，以衡量节点的连接性贡献，该度量标准是节点邻居差异的总和。此外，为了反映节点的充电需求，采用了一个称为能量关键指数的指标来加权关键指数，该指标是节点消耗的能量与其总能量的归一化比值。然后，我们提出了一个优化问题，其目标是最大化节点的总加权关键指数，以构建充电巡回，同时受移动充电器行驶距离的约束。由于问题的 NP 难度，提出了一种启发式算法来解决它。启发式算法包括三个步骤，即生成树生长、巡回构建和巡回改进。最后，我们将提出的算法与最新的调度算法进行了比较。获得的结果表明，所提出的算法是一种很有前途的算法。
