Near Field Communication

Wed Apr 07, 2010 | By Unaiza Ahsan- News Team

One of the eight mobile technologies to watch out for in 2010 by Gartner, NFC or Near Field Communication is a high frequency, short-range, wireless communication technology that provides data communication between mobile devices about 10 centimetres (or round about 4 inches) apart. This technology extends the ISO/IEC 14443 contactless card standard which joins the smartcard's and reader's interfaces into one mobile device. An NFC device is capable of communicating with currently employed contactless infrastructure as well as other NFC devices. The applications are vast and very interesting. Imagine your phone doing the payment as you purchase a plane ticket, or downloading data from the internet by pointing your phone to a 'smart poster' on the streets. The possibilites and conveniences are endless.

The Physics behind this technology is a concept we all studied in high school: Magnetic field induction. This phenomenon occurs when two loop antennas are placed within each other's magnetic field, thus creating an air-core transformer out of the two. The operational frequency band is the ISM band of 13.56 Mhz, and the bandwidth is 14KHz. Data rates range from 106 to 848 kbits per second. There are two modes of operation: Passive communication mode and Active communication mode. The passive mode, the sender (or initiator) device generates the carrier field, and receiving device is passive, or just needs to modulate the existing fields. No power is needed for the target device. But in active mode, the sender as well as receiver both generate their own carrier fields, and both need power supplies.

Data communication requires two different types of coding (digital communications course anyone?). If a device is in active mode, and is transmitting data at 106 kbits/sec, modified Miller coding (100% modulation ratio) will be used. Else, Manchester coding is used (modulation ratio: 10%). A setback associated with NFC is that there is no prevention/protection against evesdropping, so a security risk is always present. Data can be modified on its way, and thus NFC-enabled devices have to use cryptographic methods to secure the data channel.