Dasgupta Rumpa, Yoon Seokhoon
Department of Electrical and Computer Engineering, University of Ulsan, Ulsan 680-749, Korea.
Sensors (Basel). 2017 Apr 1;17(4):742. doi: 10.3390/s17040742.
In wireless sensor networks, the data collected by sensors are usually forwarded to the sink through multi-hop forwarding. However, multi-hop forwarding can be inefficient due to the energy hole problem and high communications overhead. Moreover, when the monitored area is large and the number of sensors is small, sensors cannot send the data via multi-hop forwarding due to the lack of network connectivity. In order to address those problems of multi-hop forwarding, in this paper, we consider a data collection scheme that uses mobile data collectors (MDCs), which visit sensors and collect data from them. Due to the recent breakthroughs in wireless power transfer technology, MDCs can also be used to recharge the sensors to keep them from draining their energy. In MDC-based data-gathering schemes, a big challenge is how to find the MDCs' traveling paths in a balanced way, such that their energy consumption is minimized and the packet-delay constraint is satisfied. Therefore, in this paper, we aim at finding the MDCs' paths, taking energy efficiency and delay constraints into account. We first define an optimization problem, named the delay-constrained energy minimization (DCEM) problem, to find the paths for MDCs. An integer linear programming problem is formulated to find the optimal solution. We also propose a two-phase path-selection algorithm to efficiently solve the DCEM problem. Simulations are performed to compare the performance of the proposed algorithms with two heuristics algorithms for the vehicle routing problem under various scenarios. The simulation results show that the proposed algorithms can outperform existing algorithms in terms of energy efficiency and packet delay.
在无线传感器网络中，传感器收集的数据通常通过多跳转发被转发到汇聚节点。然而，由于能量空洞问题和高通信开销，多跳转发可能效率低下。此外，当监测区域较大且传感器数量较少时，由于缺乏网络连通性，传感器无法通过多跳转发发送数据。为了解决多跳转发的这些问题，在本文中，我们考虑一种使用移动数据收集器（MDC）的数据收集方案，MDC会访问传感器并从它们那里收集数据。由于无线功率传输技术最近的突破，MDC还可用于为传感器充电，以防止它们耗尽能量。在基于MDC的数据收集方案中，一个重大挑战是如何以平衡的方式找到MDC的行进路径，使得它们的能量消耗最小化并且满足分组延迟约束。因此，在本文中，我们旨在找到MDC的路径，同时考虑能量效率和延迟约束。我们首先定义一个优化问题，称为延迟约束能量最小化（DCEM）问题，以找到MDC的路径。我们制定了一个整数线性规划问题来找到最优解。我们还提出了一种两阶段路径选择算法来有效解决DCEM问题。进行了仿真，以在各种场景下将所提出算法的性能与两种用于车辆路径问题的启发式算法进行比较。仿真结果表明，所提出的算法在能量效率和分组延迟方面可以优于现有算法。
