At what speed does NFC transfer data

Near Field Communication (NFC)

by Dominic Bremer

Table of Contents

1. Introduction
2. How it works
3. Special features
4. NFC in practice
5. Summary

1. Introduction

Near Field Communication (NFC) is a wireless near-field radio technology and is based on a combination of RFID and other wireless connection technologies. NFC works in a range of approx. 10 cm and connects two devices with each other that can exchange data on the basis of a peer-to-peer protocol. In addition, there are many other options, such as configuring other wireless protocols, transferring money or using it as a bus and train ticket.
NFC was developed jointly by Sony and Philips and is now accepted as ISO / IEC 18092 and ECMA 340 standards. At the beginning of 2004, both parties founded the NFC forum together with Nokia to promote the joint development of NFC. Numerous other companies now belong to this forum, including MasterCard, Microsoft, Motorola, Samsung, Texas Instruments and Visa.

2. How it works

The NFC protocol (NFCIP-1) operates in the globally available and unregulated RF ("Radio Frequency") band with 13.56 MHz. As a result, there are no restrictions and no licenses are required. However, due to various country-specific requirements with regard to electromagnetic emissions, in practice the distance at which two devices can connect to one another is very different. According to the ECMA, it is 0 to approx. 20 cm.

The protocol distinguishes between the initiator and the Target the communication. The initiator is the device that initializes and controls the exchange of data; the target is the device that responds to the initiator's request. NFC-enabled devices implement the "listen before talk" principle, which means that the initiator first looks for an active radio signal and is only allowed to start transmitting a signal when no other device is transmitting data

The connection is established by the initiator at a certain speed (optionally 106, 212 or 424 kbit / s), then the target determines the speed and changes it if this should be necessary during communication. The connection is terminated either by the respective application or when the devices leave the maximum range.

A distinction is also made between the two operating modes: Active mode and Passive mode:

- In the Active mode both devices generate their own RF field to transmit the data. Both of them need their own energy supply.
- In the Passive mode only one device generates the RF field (according to the specification of the initiator), while the passive target modulates the existing field in order to transmit the data. It does not need its own energy supply for this, as it can draw the required energy from the electromagnetic field.

Every NFC-enabled device supports these two communication modes. In contrast to RFID, there is no strict separation between the active reader and the passive tag.

3. Special features

Due to its special technical characteristics, according to the ECMA specification, NFC has a number of advantages over other protocols:

- The short distance at which NFC devices operate has a certain degree security (in terms of unintentional connections). In order for two devices to communicate, they must be placed very close to each other. This protects against unintentional connections.
- The process of establishing a connection appears "natural" from a psychological point of view and is very beneficial to the user familiar: as soon as the respective devices touch, they communicate with each other.
- Passive mode allows devices that are particularly sensitive to the Saving energy arrives (e.g. mobile phone, PDA) to run in power-saving or stand-by mode, while all communication originates from the other side.
- NFC is a short-range protocol and therefore does not have the problem of many long-range protocols such as Bluetooth or WLAN to select the right device from the mass of devices within its range in order to deliver the corresponding parameters of the connection. NFC can be used here for such a Connection establishment to automateby holding the two devices close to each other. In this way, a connection can first be established via NFC, in which the connection parameters of the respective protocol are exchanged. If the connection is established, the devices can be separated from each other. The previously created long-range connection would be retained. This procedure is also recommended when large amounts of data are planned to be exchanged, since NFC does not provide the required bandwidth here.
- The NFC protocol is compatible to various contactless smart card protocols (e.g. Sony's FeliCa and Philips' Mifare). An NFC device can therefore not only read a smart card, but also function as a smart card itself. Possible areas of application are dealt with in the following section.

4. NFC in practice

It is difficult to predict which application NFC will ultimately find in practice - however, there are a number of possible scenarios from the manufacturers and also initial field studies. Let's take a look at the following three areas:

e-ticketing / mobile payment
One area where NFC will securely find use is in transferring funds and acting as a bus and train ticket. At the beginning of 2005, a six-month pilot project was started with the Frankfurt Rhein-Main Verkehrsverbund (RMV) to test how mobile phones with NFC chips can be used to access an existing wireless smart card infrastructure. This test run enables the passengers of the RMV in Hanau (near Frankfurt) to use their Nokia 3220 mobile phone as a bus ticket. All they have to do is hold it briefly against a contactless reader when getting in and out to log in or out. An NFC-enabled mobile phone is also used to check the ticket, which reads the data from the passengers' mobile phones and checks their validity.

Mobile entertainment
The possibility of transferring data from one NFC device to another creates the following two scenarios: Someone takes photos with the built-in camera in their mobile phone or PDA while on the move. At home, the resulting images can then be viewed on the television - simply by holding your mobile phone up to the TV set. Another application scenario would be, for example, "intelligent advertising posters" that are equipped with a corresponding tag. If a user touches this poster with his NFC-enabled mobile phone, he would automatically download music, ring tones, tickets or vouchers. It would also be possible to download a URL that is then automatically called up by the device's web browser.

Business travel
NFC could also enable business travelers to book and pay for airplane tickets and hotel reservations at home on their PC. They would then transfer the information to a contactless Visa card and use it as a ticket. Once at the hotel, the room key could be transferred to the user's cell phone, which he can then use to enter his room.

5. Summary

The areas in which NFC will ultimately be used primarily depends on how end customers react to it and what personal benefits they will derive from it. An evaluation of the field tests, e.g. in Hanau, could provide important findings in this regard. In any case, the manufacturers seem to be willing to establish this technology on the market. The establishment of the NFC forum was an important step in setting a standard and ensuring interoperability between the individual end devices. According to the market research company ABI Research, every second cell phone should be NFC-capable by 2009.
Finally, a list of the advantages and disadvantages of near field communication:

- Contactless exchange of data over short distances
- No complex configuration measures when establishing a connection
- very energy efficient ("passive mode")
- versatile
- no separation between tag and reader (as with RFID)

- small number of participants (always only 2 devices)
- low transmission rate compared to other technologies (max. 424 kbit / s)


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