How does it work?
Near Field Communication (NFC) is a wireless communication technology – also known as short distance radio communication – that permits the data transfer of small data amounts over short distances.
This technology has the advantage that radio transmitters can work with little energy coming only via the magnetic field and thus be inexpensive. Because data is only transmitted over short distances (a few centimeters), sniffing - known from WLAN or Bluetooth networks - is practicably impossible. Like known from Bluetooth peer-to-peer communication NFC devices detect each other automatically but substantially faster.
Devices that support NFC can work both in active and passive mode. When working in the “passive mode” no energy is needed for reading out data stored and thus devices can even work when switched off. Thereby NFC devices can be used for contactless smart card applications.
NFC technology gains transfer speeds between 106 up to 424 KBit per second, an extension to 1 MBit per second is in preparation. The data transfer is based on an inductive coupling at 13,56 MHz. A transaction always needs two parties, an Initiator sending the data and a Target receiving the information.
The NFC transfer speed of 106, 212 or 424 KBit per second is negotiated between the Initiator and the Target. The data transfer is half-duplex, meaning at one time one device is only in sending and the other is only in receiving mode. The device in receiving mode powers off its RF field and only listens to data sent over the RF field by the sending device.