12-01-2013, 02:45 PM
NEAR FIELD COMMUNICATION
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ABSTRACT
Near field communication (NFC) is one of the latest wireless communication technologies. It is a short range wireless communication which offers safe and intuitive communication between electronic devices.
Introduction
NFC is a short range wireless technology that allows communications to take place between devices that either touch or are momentarily held close together. The technology works via magnetic field induction and operates on an unlicensed radio frequency band. Tags are embedded within devices. The devices could be mobile devices such as mobile phones or NFC stations such as ticket barriers or cash registers. NFC enables devices that are held together to share information either in one direction or both. NFC is based on radio frequency identification (RFID) technology, which is compatible with most of the contactless transportation and ticketing solutions that are commonly used around the world to enable quick and smooth flow of people within public transportation systems or ticketed environments. The terms ‘far field’ and ‘near field’ describe the fields around an antenna or, more generally, any electromagnetic radiation source .The names imply that two regions with a boundary between them exist around an antenna. These boundaries are not fixed in space. Instead, the boundaries move closer to or farther from an antenna, depending on both the radiation frequency and the amount of error an application can tolerate. The number of short-range applications for NFC technology is growing continuously, appearing in all areas of life. Especially the use in conjunction with mobile phones offers great opportunities.
Importance of NFC
NFC is an important technology for a number of reasons and they are reach and availability, variety of use, ease of use, security, value added services and infrastructure. NFC has the potential over time to be integrated into every mobile handset in the world. This would give the technology a potential reach as global as the mobile phone itself. By integrating NFC technology into a mobile handset, users could gain access to a number of new services via their phone and this makes NFC highly reachable and available. It can be used for a number of tasks, from payment for goods to ticketing and from pairing devices to sharing information or discovering new services. Because NFC only requires that two devices touch in order to communicate, NFC can simplify many tasks, from opening a web browser on a mobile phone to pairing two bluetooth devices automatically to accessing wireless hotspots simply and easily. NFC requires a user to actively wave or hold their mobile device against another device or NFC station to activate a service or to share information. In doing so, the technology requires the user to make a positive action to confirm the transaction or exchange. In addition it is possible to build multiple levels of security into an NFC enabled device. NFC is compatible with the current contactless infrastructure used as a platform for ticketing, transportation, and increasingly payment, across the world. NFC mobile devices could easily be made compatible with the major transport systems world-wide that use contactless access to services. It is also compatible with the increasingly popular “wave to pay” credit and debit cards that are being rolled out in many countries. The roll out of NFC to existing contactless environments is straight forward. Users know how the system works and much of the infrastructure is in place already. The roll out of NFC is an extension to services that already exist, but enhanced with the additional element of a mobile phone’s user interface and a connection to the internet.
Specifications
NFC communicates via magnetic field induction, where two loop antennas are located within each other's near field, effectively forming an air-core transformer. It operates within the globally available and unlicensed radio frequency ISM band of 13.56 MHz, with a bandwidth of almost 2 MHz. The working distance with compact standard antennas is up to 20 cm. Supported data rates are 106, 212, or 424 kbit/s .There are two modes and are passive communication mode and active communication mode. In passive the initiator device provides a carrier field and the target device answers by modulating existing field. In this mode, the target device may draw its operating power from the initiator-provided electromagnetic field, thus making the target device a transponder. While in active both initiator and target device communicate by alternately generating their own field. A device deactivates its radio frequency field while it is waiting for data. In this mode, both devices typically need to have a power supply. NFC employs two different codings to transfer data. If an active device transfers data at 106 kbit/s, a modified miller coding with 100% modulation is used. In all other cases manchester coding is used with a modulation ratio of 10%. NFC devices are able to receive and transmit data at the same time. Thus, they can check the radio frequency field and detect a collision if the received signal does not match with the transmitted signal.
Standards and Compatibility
Near Field Communication is an open platform technology, developed by Philips and Sony. NFC, described by NFCIP-1 (Near Field Communication Interface and Protocol 1), is standardized in ISO 18092, ECMA 340 as well as in ETSI TS 102 190. These standards specify the basic capabilities, such as the transfer speeds, the bit encoding schemes, modulation, the frame architecture, and the transport protocol. Furthermore, the active and passive NFC modes are described and the conditions that are required to prevent collisions during initialization. NFC devices not only implement NFCIP-1, but also NFCIP-2, which is defined in ISO 21481 , ECMA 352 and ETSI TS 102 312. NFCIP-2 allows for selecting one of three operating modes and are NFC data transfer (NFCIP-1), proximity coupling device (PCD) and vicinity coupling device (VCD), defined in ISO 15693 . NFC devices have to provide these three functions in order to be compatible with the main international standards for smartcard interoperability, ISO 14443 (proximity cards, e.g. Philip’s Mifare ), ISO 15693 (vicinity cards) and to Sonys FeliCa contactless smart card system. Hence, as a combination of smartcard and contactless interconnection technologies, NFC is compatible with today’s field proven RFID-technology. That means, it is providing compatibility with the millions of contactless smartcards and scanners that already exist worldwide.