无线可充电传感器网络中全向充电问题研究

发布时间：2019-03-20 20:01

【摘要】：随着无线传感器网络的广泛应用,针对其研究也越来越多,一个热点问题是能源供应。众所周知,工业电池仍是各种移动设备的瓶颈,频繁更换电池消耗大量人力、物力和财力。在这种情况下,无线可充电传感器网络应运而生。在无线可充电传感器网络中,充电器节点通过无线充电技术为传感器节点提供能量。这种能量供应模式大大增加了网络的可靠性、灵活性及可扩展性。本文研究无线可充电传感器网络中的全向充电问题。全向充电是我们首次提出的概念,指目标区域内任意点上的传感器不管其接收天线朝哪个方向都能被一个或多个定向充电器充电而且充电功率不小于某个给定阈值。我们主要解决两个问题:一、在充电器位置确定情况下,检测目标区域是否能够实现全向充电;二、在充电器位置随机情况下,确定目标区域实现全向充电的上限概率。我们的主要贡献有如下四点:1.我们第一个提出并研究全向充电问题,建立了充电器和充电设备之间的定向充电模型。全向充电模型广泛适应于无线可充电传感器网络及毫米波蜂窝网等领域中。2.我们提出一个行之有效的方法来检测充电器位置确定时目标区域是否实现全向充电。首先,我们设计分段常量近似方法把非线性的充电模型离散化,根据充电器充电范围的相互叠加将目标区域划分为多个子区域,进而转化为研究所有子区域上的全向充电问题。接着,我们提出了区域最小覆盖集提取算法,此算法将子区域上的全向充电问题转化为其边界上若干点的全向充电问题,大大降低了计算复杂度。最后,如果所有子区域都实现全向充电,则目标区域实现全向充电,否则目标区域未实现全向充电。3.我们推导出充电器位置随机分布情况下目标区域实现全向充电的上限概率。首先,我们将目标区域划分为多个等边三角形。我们证明了如果某种弱化配置的充电器网络可实现所有三角形顶点的全向充电,那么在正常配置下目标区域即可实现全向充电。随后,我们计算目标区域内一个随机点被全向充电的概率,进而得出所有三角形顶点实现全向充电的概率。最终,我们得到目标区域实现全向充电的上限概率。4.我们做了仿真实验和现场实验来验证我们算法的准确性和高效性。实验结果表明,我们的算法比在无线传感器网络中广泛应用的基于自适应算法的全向覆盖检测算法性能提高至少20%;我们的理论结果与现场实验的一致性高达93.6%。
[Abstract]:With the wide application of wireless sensor networks (WSNs), there are more and more researches on WSNs, one of the hot issues is energy supply. As we all know, industrial batteries are still the bottleneck of various mobile devices, the frequent replacement of batteries consumes a lot of manpower, material and financial resources. In this case, wireless rechargeable sensor networks emerge as the times require. In wireless rechargeable sensor networks, charger nodes provide energy for sensor nodes through wireless charging technology. This energy supply mode greatly increases the reliability, flexibility and scalability of the network. In this paper, the omni-directional charging problem in wireless rechargeable sensor networks is studied. Omni-directional charging is the first concept that the sensor at any point in the target region can be charged by one or more directional chargers regardless of the direction of the receiving antenna and the charging power is no less than a given threshold. We mainly solve two problems: one is to detect whether the target region can achieve omnidirectional charging when the charger position is determined and the other is to determine the upper limit probability of the target region to realize omnidirectional charging under the random charger position. Our main contributions are as follows: 1. We first proposed and studied the omni-directional charging problem and established a directional charging model between the charger and the charging device. The omni-directional charging model is widely used in wireless rechargeable sensor networks and millimeter wave cellular networks. We propose an effective method to detect whether the target area can achieve omni-directional charging when the charger position is determined. Firstly, we design a piecewise constant approximation method to discretize the nonlinear charging model. According to the superposition of charging range of charger, the target region is divided into several sub-regions, and then the problem of omni-directional charging on the sub-region is studied. Then, we propose a region minimum covering set extraction algorithm, which transforms the omni-directional charging problem on the sub-region into the omni-directional charging problem at several points on the boundary of the sub-region, which greatly reduces the computational complexity. Finally, if all sub-areas are charged omni-directional, the target area will be charged omni-directional, otherwise the target area will not be charged omni-directional. We derive the upper bound probability of the target region to realize omni-directional charging under the random distribution of the charger position. First, we divide the target region into multiple equilateral triangles. We have proved that if a certain weakly configured charger network can achieve omni-directional charging of all triangle vertices, then the target area can be charged omni-directionally under normal configuration. Then, we calculate the probability that a random point in the target region is charged omni-directionally, and then get the probability that all triangle vertices can realize omni-directional charging. Finally, we get the upper bound probability of achieving omni-directional charging in the target region. 4. We have done simulation and field experiments to verify the accuracy and efficiency of our algorithm. The experimental results show that the performance of our algorithm is at least 20% higher than that of the algorithm based on adaptive algorithm which is widely used in wireless sensor networks, and the agreement of our theoretical results with the field experiments is as high as 93.6%.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212.9;TN929.5

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