College of Computer Science, Sichuan University, Chengdu 610065, China.
College of Fundamental Education, Sichuan Normal University, Chengdu 610068, China.
Sensors (Basel). 2018 Aug 23;18(9):2771. doi: 10.3390/s18092771.
The employment of mobile vehicles to charge sensors via wireless energy transfer is a promising technology to maintain the perpetual operation of wireless sensor networks (WSNs). Most existing studies assumed that sensors are powered with off-the-shelf batteries, e.g., Lithium batteries, which are cheap, but it takes some non-trivial time to fully charge such a battery (e.g., 30⁻80 min). The long charging time may incur long sensor dead durations, especially when there are many lifetime-critical sensors to be charged. On the other hand, other studies assumed that every sensor is powered with an ultra-fast charging battery, where it only takes some trivial time to replenish such a battery, e.g., 1 min, but the adoption of many ultra-fast sensors will bring about high purchasing cost. In this paper, we propose a novel heterogeneous sensor network model, in which there are only a few ultra-fast sensors and many low-cost off-the-shelf sensors. The deployment cost of the network in the model is low, as the number of ultra-fast sensors is limited. We also have an important observation that we can significantly shorten sensor dead durations by enabling the ultra-fast sensors to relay more data for lifetime-critical off-the-shelf sensors. We then propose a joint charging scheduling and routing allocation algorithm, such that the longest sensor dead duration is minimized. We finally evaluate the performance of the proposed algorithm through extensive simulation experiments. Experimental results show that the proposed algorithm is very promising and the longest sensor dead duration by it is only about 10% of those by existing algorithms.
利用移动车辆通过无线能量传输为传感器充电是一种很有前途的技术，可以维持无线传感器网络（WSN）的永久运行。大多数现有研究都假设传感器由现成的电池（例如锂电池）供电，这种电池价格便宜，但充满电需要相当长的时间（例如 30-80 分钟）。较长的充电时间可能会导致传感器长时间无法工作，尤其是需要为大量寿命关键的传感器充电时。另一方面，其他研究则假设每个传感器都由超快速充电电池供电，只需很短的时间就可以为电池充电，例如 1 分钟，但采用许多超快速传感器会带来高昂的购买成本。在本文中，我们提出了一种新颖的异构传感器网络模型，其中只有少数超快速传感器和许多低成本的现成传感器。由于超快速传感器的数量有限，因此该模型中的网络部署成本较低。我们还观察到一个重要现象，即通过使超快速传感器为寿命关键的现成传感器转发更多数据，可以显著缩短传感器的无工作时间。然后，我们提出了一种联合充电调度和路由分配算法，以使最长的传感器无工作时间最小化。最后，我们通过广泛的仿真实验评估了所提出算法的性能。实验结果表明，所提出的算法非常有前途，其最长的传感器无工作时间仅为现有算法的约 10%。
