Near field communication, NFC
Near Field Communication, NFC is a short-range wireless data transmission technology that provides data exchange between devices located at a distance of about 10 centimeters from each other. It was announced in 2004.
The technology is backward compatible with the widely used Smart Card standard based on ISO/IEC 14443 A (for example, Mifare) and ISO/IEC 14443 V as well as JIS X 6319-4 (FeliCa). For the exchange between the two devices, the new ECMA-340 protocol and the ISO/IEC 18092 standard were developed. In 2004, the NFC Forum was created, which included Sony, NXP, and Nokia. Companies began to work together on new technology to ensure the compatibility and correct interaction of the relevant devices and services. As a result, NFC supports all the standards listed above.
Thus, the NFC technology is compatible with the existing infrastructure of contactless cards used in public transport and payment systems but is aimed primarily at use with mobile devices.
The ISO 14443 standard regulates the organization of communication within publicly accessible and unlicensed ISM radio frequencies (industrial, scientific and medical radio frequencies). As in the technologies that meet this standard, in NFC, communication is maintained by electromagnetic induction, when two loop antennas are located within each other's near field. Due to the inductive coupling of the loop antennas of the interrogator and premix device, the passive receiving device influences the active interrogator. Changes in the impedance of the receiving device cause amplitude or phase changes in the antenna voltage of the interrogator. This modulation method is called load modulation.
The operating frequency of the NFC communication technology is 13.56 MHz, the data transfer rate is a maximum of 424 kbit/s with a distance between devices up to 4 cm. With an increase in the distance, the speed drops to 212 kbit/s and, at the maximum distance for this technology of 20 cm, to 106 kbit/s.3 The signal undergoes amplitude shift keying with a depth of 100% (OOK, on-off keying) or 10% (ASK, amplitude shift keying) and phase-shift keying (BPSK, binary phase-shift keying).
Comparison with other short-range technologies
Compared to Bluetooth, another short-range communication technology, NFC has a much lower transfer rate (424 kbit/s versus 24 Mbit/s). But the connection setup time is only 0.1 s versus 6 s for Bluetooth, so NFC can be used to quickly make connections in other wireless technologies, such as Bluetooth, Wi-Fi, or UWB (ultra-wideband), and then transfer data already with higher speed. The short-range of NFC (10–20 cm) can be considered both as a disadvantage and as a virtue since this increases the security level and one can easily use NFC in an environment saturated with other devices with a wireless connection. Unlike Bluetooth, NFC is compatible with RFID (radio frequency tags) technology.
Modes of operation
NFC defines three main modes of operation:
- Passive (smart card emulation). A passive NFC device (receiver or target) behaves like a contactless card of one of the existing standards.
- Transmission of information between peer-to-peer devices.
- Active mode (read or write; reader mode). The active device (initiator or reader) acts as a scanner of NFC tags (analogs of bar codes) containing various information.
Each mode of operation (card emulation, peer-to-peer mode, and read/write mode) can be combined with one of the following transmission technologies:
- NFC-A (backward compatible with ISO/IEC 14443 A).
- NFC-B (backward compatible with IS /IEC 14443 B).
- NFC-F (backward compatible with JIS X 6319-4).
In order to support various technologies, the NFC device first sends the corresponding request signal in polling mode and waits for a response from the NFC-A, NFC-B and NFC-F tags. After receiving a response from a compatible device, the NFC device sets the appropriate communication mode (NFC-A, NFC-B or NFC-F mode).
Areas of use
- Data exchange between smartphones, tablets, cameras, etc. If to arrange the devices so that their NFC modules can establish a connection, one can easily transfer data (links, contact information, photos, and documents) from one device to another.
- Non-cash payments using NFC smartphones or NFC cards are allowed by some supermarkets and public transport networks (subway, land transport, suburban electric trains, etc.). With the help of NFC, one can pay for entry to some entertainment events. According to the NFC standard, there are Visa PayWave and MasterCard PayPass payment cards with an integrated antenna. Google, MasterCard, Citibank, Sprint and First Data have created the Google Wallet service, which is installed on some Android phones. The application allows turning a smartphone into a credit card, by which one can pay in any terminal that supports PayPass technology.
- Identification. With the help of NFC, one can transfer an identification or business card and other information about the owner in a secure mode.
- Information transfer and control using NFC tags. The tag may contain information about any product or event (concert or film), a link to the website, i.e. it can be used for promotional purposes.6 One can program a tag using a smartphone on which special programs are installed. Later, when the smartphone comes close to the tag, the signal received from it can act as a trigger that runs a program on the smartphone. For example, if the tag is glued to the headboard, then when one brings an NFC smartphone in it, airplane mode can be turned on. Similarly, NFC tags can be used to solve many other problems in microautomaticization.