无线传感网监测质量感知的最小成本充电调度研究

The limited sensor battery capacity is one of the main obstacles that hinder the wide use of wireless sensor networks. In this project, we will study the use of wireless charging vehicles for charging sensors in a large-scale wireless sensor network, by utilizing the novel wireless energy transfer technology. We note that existing studies do not treat all sensors in the network discriminatively and consider only how to charge as many sensors as possible before their energy expirations. However, there are many types of sensors in a sensor network and the data importance from different types of sensors usually significantly varies, depending on the application of the sensor network. Furthermore, not only does a sensor cannot continue its monitoring task if it has depleted its energy, but also other live sensors cannot upload their sensing data to the base station via the data relay of the sensor. Therefore, the monitoring quality of the sensor network will be significantly deteriorated by the energy expirations of sensors in existing works. Unlike existing studies, we will investigate three fundamental charging scheduling problems for sensor networks in this project. The first problem is how to measure the impact on the network monitoring quality by dead sensors. The second one is to schedule charging vehicles to replenish a set of to-be-charged sensors, such that not only the impact on the network monitoring quality by dead sensors is minimized, but also the traveling cost of the charging vehicles for charging the sensors is minimized, too. The last problem is to schedule the charging vehicles to charging the sensors for the entire network period, not just at some time point, so that the accumulative traveling cost the vehicles for the period is minimized.

传感器有限的电池容量是制约无线传感器网络广泛应用的最根本瓶颈之一。在本项目中，我们研究调度充电车利用最新的无线充电技术为传感器充电。现有相关研究将网络中所有传感器同等对待，然后探讨了如何将尽可能多的传感器在它们耗尽电量之前充满电。我们注意到，网络中不同类型传感器的数据重要性不一样，而且一个传感器耗尽电量死亡后不仅它自己不能继续进行监测任务，很多其它传感器也可能无法通过该传感器将它们的数据转发回基站。因此，在现有研究中，那些无法被及时充电的传感器死亡后可能大大降低网络的监测质量。与现有研究不同，在本项目中，我们将研究为传感器网络充电调度的三个核心问题：一是如何量化传感器死亡对网络监测质量的影响；二是如何调度充电车为一批传感器充电，使得不仅最小化传感器死亡对网络监测质量的影响，而且最小化充电车的行驶开销成本；三是在整个网络周期内调度充电车为传感器充电，使得最小化充电车在整个周期内的行驶开销。

在本项目中，我们研究了调度充电车利用最新的无线充电技术为传感器充电。深入研究了为传感器网络充电调度的三个核心问题：一是如何量化传感器死亡对网络监测质量的影响。具体是：提出效用函数和结构洞来对传感器耗尽电量死亡后对网络监测质量影响的度量，设计了基于静态路由和动态路由的充电调度策略、以及路由与充电联合调度策略。二是如何调度充电车为一批传感器充电，使得不仅最小化传感器死亡对网络监测质量的影响，而且最小化充电车的行驶开销成本。具体是：首次提出部分充电的概念、使得能够大大缩短传感器的死亡时间、并且探讨如何在不增加充电车的行驶开销下缩短超过的死亡时间。同时探索了多充电车的协同调度，来缩短传感器的充电延迟。三是在整个网络周期内调度充电车为传感器充电，使得最小化充电车在整个周期内的行驶开销。具体是：利用单充电车携带多个便携式充电器的方式来大大提高充电效率；利用一对多充电的充电技术来缩短传感器的等待延迟、以及调度多辆能量受限的充电车对最多的传感器进行充电，达到效用最大。我们对这三个问题进行了深入的探索，提出了重要的概念、理论、和算法，并进行了严格的分析和实验验证。实验证实了算法的有效性。