The low-power wide-area network (LPWAN) technologies, such as LoRa, Sigfox, and NB-IoT, bring new renovation to the wireless communication between end devices in the Internet of things (IoT), which can provide larger coverage and support a large number of IoT devices to connect to the Internet with few gateways. Based on these technologies, we can directly deploy IoT devices on the candidate locations to cover targets or the detection area without considering multihop data transmission to the base station like the traditional wireless sensor networks. In this paper, we investigate the problems of the minimum energy consumption of IoT devices for target coverage through placement and scheduling (MTPS) and minimum energy consumption of IoT devices for area coverage through placement and scheduling (MAPS). In the problems, we consider both the placement and scheduling of IoT devices to monitor all targets (or the whole detection area) such that all targets (or the whole area) are (or is) continuously observed for a certain period of time. The objectives of the problems are to minimize the total energy consumption of the IoT devices. We first, respectively, propose the mathematical models for the MTPS and MAPS problems and prove that they are NP-hard. Then, we study two subproblems of the MTPS problem, minimum location coverage (MLC), and minimum energy consumption scheduling deployment (MESD) and propose an approximation algorithm for each of them. Based on these two subproblems, we propose an approximation algorithm for the MTPS problem. After that, we investigate the minimum location area coverage (MLAC) problem and propose an algorithm for it. Based on the MLAC and MESD problems, we propose an approximation algorithm to solve the MAPS problem. Finally, extensive simulation results are given to further verify the performance of the proposed algorithms.

中文翻译：

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通过物联网中的设备放置和调度实现高效能源利用

LoRa、Sigfox、NB-IoT等低功耗广域网（LPWAN）技术为物联网终端设备间的无线通信带来了新的变革，可以提供更大的覆盖和支持大量的物联网设备通过很少的网关连接到互联网。基于这些技术，我们可以直接在候选位置部署物联网设备来覆盖目标或检测区域，而无需像传统的无线传感器网络那样考虑到基站的多跳数据传输。在本文中，我们研究了物联网设备通过放置和调度进行目标覆盖（MTPS）的最低能耗和物联网设备通过放置和调度进行区域覆盖（MAPS）的最低能耗问题。在问题中，我们考虑物联网设备的放置和调度来监控所有目标（或整个检测区域），以便在一段时间内连续观察（或正在）观察所有目标（或整个区域）。问题的目标是最小化物联网设备的总能耗。我们首先分别提出了 MTPS 和 MAPS 问题的数学模型，并证明它们是 NP-hard 问题。然后，我们研究了 MTPS 问题的两个子问题，最小位置覆盖（MLC）和最小能耗调度部署（MESD），并为每个子问题提出了一个近似算法。基于这两个子问题，我们提出了MTPS问题的近似算法。之后，我们研究了最小位置区域覆盖（MLAC）问题并提出了一种算法。基于 MLAC 和 MESD 问题，我们提出了一种近似算法来解决 MAPS 问题。最后，给出了大量的仿真结果，以进一步验证所提出算法的性能。