Most IoT devices are connected to cloud platforms which forward commands from smartphones to implement remote control. Such control depends on the Internet provided by Wi-Fi routers to maintain the link between the controlled device and cloud platforms. But once the Wi-Fi routers disconnect from the Internet, remote control will be paralyzed. At this point, local control will be a good supplement for sending commands, thus preventing the IoT devices from a full-out breakdown due to network exceptions.
As shown in Figure 8.1, a local control framework based on Wi-Fi in a LAN consists of a Wi-Fi router, a controlling device, and a controlled device. The controlling device can be a smartphone or a computer that can run TCP/IP protocol stack. It should be connected to the same Wi-Fi router as the controlled device, to ensure that they are in the same LAN for data communication.
As for local control based on Bluetooth, Wi-Fi routers are not needed. Smartphones can directly connect to the controlled device through Bluetooth and realize point-to-point data transmission.