Battery operated sensors means that the sensor and radio transceiver (or simply transmitter) should be in “sleep mode” most of the time to save battery power. The sensor will wake up on a timer or on some event trigger, to do the actual sensor measurement and a radio transmission. In order to support two-way communication, a common technique is for the sensor to listen for a command only in a short time window after the transmission. This is a technique used in Wireless M-Bus, KNX RF Multi and Sigfox. These standards are designed for minimum power consumption and battery operation, and battery lifetime of 15-20 years can be achieved. A mesh network can have battery operated nodes, but only as “end nodes”, that does not take part in the mesh routing. KNX RF Multi also provides solutions for receivers that are listening for commands using polling. Again, most of the time the radio is in sleep mode, but periodically it wakes up and listen for any radio communication. The transmitter will send a long preamble, for the receiver to catch. The average current consumption by the receiver can therefore be kept very low.
Last Update: August 8, 2017