The Internet of Things (IoT) will bring about the next industrial revolution in Industry 4.0. The communication aspect of IoT devices is one of the most critical factors in choosing the suitable device for the suitable usage. So far, the IoT physical layer communication challenges have been met with various communications protocols that provide varying strengths and weaknesses. Moreover, most of them are wireless protocols due to the sheer number of device requirements for IoT. This paper summarizes the network architectures of some of the most popular IoT wireless communications protocols. It also presents a comparative analysis of critical features, including power consumption, coverage, data rate, security, cost, and Quality of Service (QoS). This comparative study shows that Low Power Wide Area Network (LPWAN) based IoT protocols (LoRa, Sigfox, NB-IoT, LTE-M ) are more suitable for future industrial applications because of their energy efficiency, high coverage, and cost efficiency. In addition, the study also presents an industrial Internet of Things (IIoT) application perspective on the suitability of LPWAN protocols in a particular scenario and addresses some open issues that need to be researched. Thus, this study can assist in deciding the most suitable protocol for an industrial and production field.

翻译：物联网（IoT）将引领工业4.0时代的下一场工业革命。物联网设备的通信特性是选择适合用途设备的关键因素之一。迄今为止，物联网物理层通信挑战已通过多种通信协议得到应对，这些协议各有优劣。此外，由于物联网对设备数量的庞大需求，大多数协议为无线协议。本文总结了当前最流行的物联网无线通信协议的网络架构，并对关键特性（包括功耗、覆盖范围、数据传输速率、安全性、成本及服务质量）进行了比较分析。比较研究表明，基于低功耗广域网（LPWAN）的物联网协议（LoRa、Sigfox、NB-IoT、LTE-M）因其能效高、覆盖广、成本效益好而更适用于未来工业应用。同时，研究还从工业物联网（IIoT）应用视角探讨了LPWAN协议在特定场景中的适用性，并指出了若干有待研究的开放性问题。因此，本研究可为工业和制造领域选择最合适的协议提供参考依据。