Industrial Internet of Things (IIoT) connect all components of the factory by constructing low-delay and high-reliability network (wired or wireless), realizing ubiquitous interconnection and smooth data communication, and finally forming an intelligent and efficient industrial ecosystem. There are three widely used device-to-device (D2D) techniques, including Bluetooth (BT), WiFi Hotspot (WFH) and WiFi Direct (WFD), which could provide wireless connections and communications for IIoT devices when the WLANs or cellular networks are unavailable. These D2D communication techniques have gained popularity with the emergence of offloading computing as well as edge computing. Existing studies investigate the outdated versions of BT and WFH, and there are no studies comprehensively comparing them together.

In this paper, we conduct a comparative study of the three D2D communication techniques from the aspects of power consumption and transmission performance. Experimental results indicate that BT consumes the lowest power. Power consumption of BT in working state is almost equal to that of WFH and WFD in idle states. However, BT exhibits a poor performance in data transmission. The maximum transmission rate for BT is 1.6 Mbps, while the value is around 50 Mbps for WFH and WFD. We find that TCP/UDP performance of WFH is a little better than WFD. However, WFH also consumes a bit more power than WFD. As a result, WFH is nearly at the same level as WFD when considering the throughput and power consumption together. Taken the results at 2.4 GHz band as an example, the TCP throughput/power for both of them is 4.63 KB/mWs at the sender, while at the receiver, they also have the same value of 6 KB/mWs. We believe that the measurement results are fundamental for constructing high-performance and power-efficient device-to-device communication networks with IIoT devices.

工业物联网（IIoT）通过构建低延迟和高可靠性网络（有线或无线），实现无处不在的互连和流畅的数据通信，并最终形成一个智能，高效的工业生态系统，来连接工厂的所有组件。存在三种广泛使用的设备到设备（D2D）技术，包括蓝牙（BT），WiFi热点（WFH）和WiFi Direct（WFD），当WLAN或蜂窝网络处于连接状态时，它们可以为IIoT设备提供无线连接和通信。不可用。随着分流计算以及边缘计算的出现，这些D2D通信技术已变得越来越流行。现有研究对BT和WFH的过时版本进行了研究，还没有将它们进行全面比较的研究。

在本文中，我们从功耗和传输性能方面对三种D2D通信技术进行了比较研究。实验结果表明，BT功耗最低。BT在工作状态下的功耗几乎等于WFH和WFD在空闲状态下的功耗。但是，BT在数据传输方面表现较差。BT的最大传输速率为1.6 Mbps，而WFH和WFD的最大传输速率约为50 Mbps。我们发现WFH的TCP / UDP性能比WFD更好。但是，WFH也比WFD消耗更多的功率。结果，当同时考虑吞吐量和功耗时，WFH与WFD几乎处于同一水平。以2.4 GHz频段的结果为例，在发送者处，两者的TCP吞吐量/功率均为4.63 KB / mW，而在接收器处，它们的值也相同，为6 KB / mW。我们相信，测量​​结果对于使用IIoT设备构建高性能，高能效的设备到设备通信网络至关重要。