The beginner's guide to near field communications
Wave me the money
The Oyster is my world
The NFC architecture envisions multiple applications making use of the same hardware, so an NFC phone might have an application installed for London's Oyster mass-transport pre-payment system, allowing the user to board an underground train or bus by tapping the phone against a reader, but it might also have an application from British Airways for storing boarding passes and tickets, allowing a plane to be boarded with similar ease.
The same handset could then download a Visa PayWave application, enabling low-value transactions to be completed by tapping the phone against a shop's till.
But if the handset also has Mastercard PayPass installed there will user-interface issues to contend with as the till struggles to decide which payment system to debit.
Location advertising makes use of the reader in the phone to pick up information from cheap tags embedded in posters or signs. Basic tags cost around 10p (15c) a time, so can be embedded in movie posters or signposts to provide additional information.
Exhibits at the Pompidou Centre in Paris already have such tags, so the visitor can get additional information by tapping the sign. The centre supplies the handsets, as NFC hasn't yet taken the world by storm.
The N-Mark standard defines an embedded tag, which can communicate and provide encrypted authentication using power induced by the reader - such a tag can therefore be embedded in a credit card or key fob without needing its own power supply.
An N-Mark device, such as a mobile phone, incorporates a reader as well as a tag, to enabling communication with passive tags and other N-Mark devices. That communication takes place at 13.56MHz, but as the power is magnetically inducted the range is extremely limited - 200mm at best.
Retrofitting NFC is hard, but can be done using a wire to carry the signal from the Sim or SD card to an antenna bonded to the outside of the handset, or at least just inside the plastic back. Such an approach is being adopted by several network operators around the world, as a stop-gap while waiting for NFC handsets.