Ambient backscatter is a method of networking by way of alternately reflecting and absorbing radio frequencies (RF) in an environment. Ambient backscatter enables RF-powered devices to communicate with the same ambient frequencies that power them.
In the presence of RF signals, ambient backscatter-equipped devices are powered and enabled to communicate. The signals are used without interfering with the legacy devices for which they are originally intended, such as the RF sent for television reception. The ambient backscatter device selectively reflects a signal to imply a one and absorbs a signal to imply a zero. The selective reflectivity is achieved by way of antenna impedance changes in the presence of the original signal.
With ambient backscatter, the possibilities for smart devices and IoT are greatly increased. The use of existing signals means that power is not necessarily required for the device eliminating the need for batteries and power sources. This reduction in power requirements and components allows devices to not only be more compact but completely isolated. Operation while isolated means an RF-powered device using backscatter could be concealed, for example in a sensor embedded in a brick wall.
Ambient backscatter is similar in function to RFID. Wi-Fi backscatter similarly enables low-power devices to join traditional Wi-Fi networks.