How Near Field Communication Functions

How many things do you usually carry with you? If you're like me, you’ve got a wallet (or something similar) packed with credit cards, loyalty cards, and perhaps even a coupon or two. Then there's the key ring full of unidentified keys I likely won’t ever need. And on top of it all, I'm a gadget lover. On any given day, I probably carry both a smartphone and an MP3 player. It’s getting to the point where I’m tempted to channel Batman's fashion sense and create my own utility belt.

Or I could just consider swapping my current smartphone for one that features a near field communication (NFC) chip. At its core, NFC is a standard for extremely short-range radio communication. How short are we talking about? Two NFC devices can only communicate with each other at a distance of a few centimeters. Some NFC chips are made so that they can only send and receive information when the devices are in direct contact with each other.

So, an NFC chip can transmit data over a very short distance. But why is that important? We already have chips that allow communication over large areas, even across an entire building. Why would anyone choose a chip with such a restricted communication range?

There are smartphones available today equipped with NFC chips that allow you to pay for items simply by holding your phone near a receiver at the checkout. This eliminates the need for physical credit cards. And that's just the beginning – with the right phone and apps, I may not need to pursue my dreams of becoming the Dark Knight anymore.

The Potential of NFC

While NFC technology offers a wide range of possibilities, the one most commonly associated with it is making payments through your smartphone. It’s a straightforward concept: after shopping, you approach the register, pull out your smartphone, hold it near the receiver, enter a quick PIN for identification, and the purchase is charged to your digital credit card.

Several apps have already made this payment method appealing. In 2011, Google introduced Google Wallet and Google Offers, two products designed to leverage NFC technology. The primary function of Google Wallet is exactly what we've discussed — replacing your physical credit card. But it also allows you to store other items, such as loyalty cards and special promotions.

Here’s an example. There’s a coffee shop I visit often. To reward regular customers, they have a program where after buying 10 cups of coffee, I get one free. However, I need to carry a card for the barista to mark each purchase. If the shop adopts Google Wallet and I have an NFC-enabled phone with the app, the technology will track everything for me. I simply use my phone to pay, and it’ll automatically keep track of how many cups I’ve bought. When I’ve earned my free cup, my phone will notify the store, and I won’t be charged.

But satisfying my coffee cravings is just one of the many things NFC can achieve. At CES 2012, Yale Lock showcased another application for NFC. The company developed smart locks that use NFC to secure or unlock doors. By simply holding your phone up to a sensor on the door, a signal is sent from the phone to the lock, disengaging it and allowing entry. Now, we no longer need to carry credit cards, loyalty cards, or house keys!

Another exciting possibility lies in marketing. It’s feasible to embed an NFC tag in a poster, for instance. If you spot an ad that piques your interest, you can tap your NFC-enabled smartphone against the poster to receive additional information. The downside of this method is that you'll need to be very close to the poster to pick up the signal.

There are even more potential applications, such as using NFC to transmit health data or synchronize information between devices. Looking ahead, your smartphone profile might enable you to breeze through airport security by simply passing through NFC-enabled stations. The future uses of NFC are only limited by the technology’s capabilities.

Exploring NFC Potential

In 2004, three major companies – Nokia, Sony, and Philips – collaborated with the aim of creating a unified standard for near field communication technology. While their work focused on standardizing NFC, the technology behind it has roots that stretch much further back in history, starting with the connection between magnetism and electricity.

When electrons move through a conductor, they generate a magnetic field. Conversely, changes in magnetic fields can induce electrons to flow through a conductor. This relationship, known as inductive coupling, opens up a world of possibilities in electronics. One of the most practical applications of this principle is the transformer – to clarify, this is a device that converts electricity from one voltage to another, not a robot that transforms into a car.

You can easily observe the effects of inductive coupling with a straightforward experiment. Take two lengths of copper wire and coil them – the coils enhance the magnetic fields that will be generated. Connect one wire to a battery, creating a simple circuit in which electrons flow from one end of the battery, through the wire, and back into the battery. Attach the second coil to a voltmeter, a device used to measure voltage within a circuit. As you bring the coils closer together, the voltmeter's needle should move.

What’s happening here is that the magnetic field generated by the coil connected to the battery is inducing a flow of electricity through the second coil. If you move the coils apart, the needle will return to zero. The strength of inductive coupling depends on several factors, including the distance between the coils.

Radio frequency identification (RFID) tags are an example of inductive coupling in action. This technology served as a precursor to NFC. With RFID, an electronic reader generates a magnetic field, which induces electricity within the RFID tag when it is brought close. The reader detects the new magnetic field from the tag and registers it. This method is widely used in transportation and security systems, where an RFID tag embedded in a card or fob must be placed near a reader to activate. This type of technology is called passive RFID. More advanced RFID systems now include active RFID tags, which have their own power source, extending their range and allowing them to store more information [source: Zebra Technologies].

Near field communication builds upon existing technology, enabling two-way interaction between devices within a very short distance. It operates using inductive coupling, much like the way RFID tags function.

The Life of a Transaction

What exactly happens when you bring two NFC-enabled devices together? Let’s break it down with a real-life scenario: You're walking down the street and spot a poster for a show by Man or Astro-man? Being a fan of surf rock, you’re intrigued. The poster also mentions it features an NFC tag.

You quickly pull out your smartphone and activate an NFC-reading app. This triggers a signal to the NFC chip inside the phone. The chip’s circuits generate a weak magnetic field by passing electricity through them. This makes your smartphone an active NFC device — using its power to create the magnetic field. You hold the phone up to the designated spot on the poster.

The weak magnetic field from your phone induces a magnetic field in the NFC tag embedded in the poster. This causes electricity to flow through the passive NFC tag, which has no power of its own. The tag creates a radio field, which interacts with the field produced by your phone. The NFC chip in your phone detects and decodes this radio field. You now have access to a link leading to a live performance video of the band, and the app gives you the option to visit the link directly if you choose.

Some NFC interactions involve two powered devices. For example, you might want to share contact details from your phone to someone else's. In such cases, both devices work as active and passive components—when active, a device transmits information, and when passive, it receives it. The exchange happens quickly, and within moments, your contact information is transferred to the other person's phone, and theirs to yours.

An active NFC device can only establish a connection with one target device at a time — it's not possible to broadcast a message to several devices simultaneously using NFC. The active device sends data to the target and will only accept a reply from that particular target. Other NFC devices won’t engage in the communication.

It's essential to understand that NFC only governs the technology behind the transmission. It doesn’t define what data is transmitted. The various devices and apps that use NFC chips determine what information gets exchanged. Although the transmission technology is standardized, the content being transferred can vary.

NFC Specifications

As NFC is a standardized technology, it has specific parameters. The frequency used for transmitting data via NFC is 16 megahertz. Like all radio waves, these signals propagate in waves, consisting of peaks and valleys. The distance between the peak of one wave and the peak of the next is called a wavelength. At a frequency of 16 megahertz, the signal completes 16 million wavelengths per second.

The NFC forum, the organization responsible for developing and promoting the NFC standard, has designed NFC to transmit data at three different speeds. At present, an NFC device can transmit data at speeds of 106, 212, or 424 kilobits per second. These speeds are suitable for transmitting small amounts of data but are not adequate for high-demand activities such as watching videos or playing games.

NFC operates in three distinct modes. The read/write mode allows a device to read information from a tag, like the ones found on posters. The peer-to-peer mode enables two NFC-enabled devices to exchange data, allowing you to perform actions like tapping your phone with another person’s phone to share contact information. Finally, the card emulation mode makes it possible for an NFC device to imitate a smart card, such as those used for public transit or ticketing systems.

It’s crucial to keep in mind that NFC is still an evolving standard. Although it was first established in 2004, it remains a relatively new technology. The adoption of NFC has been slow in the United States, with only a few smartphone manufacturers and retail businesses supporting it. However, in other regions such as Japan, NFC is far more prevalent.

One potential risk of NFC is that it could fade into obscurity before it reaches widespread adoption. It's possible that a competing technology could emerge and take the place NFC was meant to fill. However, this is just one of the challenges that NFC might face moving forward.

Challenges of NFC

Whenever radio frequencies are in use, there’s an inherent security concern. Is it possible for a malicious individual to eavesdrop on NFC communication? The answer is, unfortunately, yes. With the right tools such as antennas, hardware, and software, unauthorized parties can intercept data during transmissions.

Even though NFC communication must occur within a very limited range—typically 10 centimeters at most, with some applications requiring even closer proximity—it is still possible for an eavesdropper to intercept signals from much farther away. The exact range from which signals can be intercepted depends on multiple factors, including whether the transmission is active or passive, the eavesdropper's antenna and receiver, and how much power the active device puts into the transmission. In some cases, an eavesdropper could potentially pick up signals from as far as 10 meters [source: Haselsteiner and Breitfuß].

It is more challenging to detect transmissions from passive devices. Nonetheless, with the right tools, an eavesdropper can pick up signals from approximately one meter away. To protect sensitive data—such as financial information—hardware and software developers implement encryption methods. This encryption ensures that both NFC components require a specific key to decrypt information. Without access to this key, the intercepted data would appear as meaningless gibberish.

Another way NFC devices can thwart eavesdropping attempts is through simultaneous transmission of data from both devices. In this method, both devices start transmitting random bit sequences—composed of 0s and 1s—at the same time. If both transmit the same bit, an eavesdropper can detect it. However, if one device transmits a 1 and the other transmits a 0, only the two devices know which bit is which, while the eavesdropper is left confused. This method ensures that both devices can securely communicate without allowing the eavesdropper to interpret the data, effectively masking the transmission from external observers.

Another potential risk with NFC is that an individual might try to disrupt communications by emitting radio signals within the NFC spectrum during a transaction. While this isn't exactly eavesdropping, it could still cause inconvenience or disturbances during the process.

Before we get too concerned about these types of issues, the widespread adoption of NFC technology must first occur. Whether NFC will truly catch on is yet to be seen. If it does, you might soon find yourself leaving most of your other gadgets behind and relying mostly on your smartphone. This could spell trouble for industries tied to the 'utility belt' market, as they might face leaner years ahead.