SmartGate – connecting wireless sensor nodes to the Internet
Wireless sensor nodes inside buildings are used to read out sensor data and to control actuators. The nodes need to operate for a long time with a single battery. Often the sensor data should be accessible via Internet from every point of the world. When using a standard Wi-Fi connection, the battery of the node would be depleted after a few hours due to idle currents in receive state. Using sensor nodes with included wake-up receivers can prolong the lifetime of the sensor network to several years. However, no gateway exists that can, on the one hand, connect itself to the Internet and on the other hand can send out the special coded wake-up signal needed by the wake-up receivers on the nodes. In this work we want to bridge this gap by introducing the SmartGate. It is a gateway that has two transceivers incorporated on a single printed circuit board (PCB). A Wi-Fi module connects itself to an existing Wi-Fi network and listens for incoming messages. A CC430 microcontroller analyzes the incoming Wi-Fi messages and builds up the corresponding wake-up signal with included 16-bit address coding. The wake-up signal is sent out using the integrated CC1101 transceiver core from Texas Instruments. A woken-up node will read out its sensor data and will transmit it back to the gateway, where it will be packed into a TCP/IP packet and sent back to the user. The use of the gateway allows the implementation of a wireless sensor network with wake-up receivers that can be accessed via Internet from every point of the world.