NFC Near Field Communication Technology
Your smartphones are doing almost everything for you but still your wallet is filled with so many credit, debit, membership, travel, rewards and identity cards. What if your one smartphone is capable of doing the same job done by so many cards, to make all payments, to gain access, for identification and as a travel card too? Yes, it is possible and the technology playing behind this possibility is Near Field Communication (NFC).
Near Field Communication is a set of standards for very short range radio communications. The working distance is almost 4cm or even less. It supports one way as well as two way communications between devices. Communication is possible between two active NFC devices as well as between an active NFC device and a passive NFC “tag“. No pairing of the devices is required for communication. NFC supported smartphones as well as applications are already in market and are quite successful.
NFC works on the principle of ”inductive coupling”. Whenever electrons flow through conductors, they generate magnetic field and when there is a change in magnetic field, it can induce electric field – the behavior is known as inductive coupling. If we have a coil and pass current through it using battery, then it will generate magnetic field. This magnetic field can induce current in nearby placed other conductor coil. As this phenomenon is based on induction hence the current induced depends highly on distance between two coils used and so does NFC. To understand this principle more, let’s first have a look at RFID tag technique, a predecessor of NFC technology.
Radio Frequency Identification (RFID) tags work on the concept of “inductive coupling“. RFID tag is an electronic chip that contains some particular information associated with it. With RFID tags, we have an electronic reader which generates the magnetic field. When we bring some RFID tag closer to this magnetic field, the magnetic field induces electricity within the tag. Hence there are changes in the field which are detected by the reader and decoded to interpret the information stored in the RFID tag.
If we are using a RFID tag that needs to be put near a reader to activate it, it’s called passive RFID. If the RFID tag also has a power source, then it’s known as an active RFID tag. In active RFID, the information storage capability and range improves. RFID tag is a one way communication. NFC uses the same principle but also provides two way communication.
NFC (Near Field Communication):
NFC works in the similar way. The devices participating in the NFC communication can be of two types. If the device has its own power source to generate magnetic field then it’s called an active NFC device otherwise it’s called a passive NFC “tag”. Out of two communicating devices, at least one device should be an active one. To rule the concept, let’s divide it in 2 parts.
- NFC One Way Communication: If I have an active NFC device, as soon as I send a signal to NFC chip, current flows and a magnetic field is generated. This magnetic field induces electricity in the closely placed passive NFC tag. It creates a radio field. The radio field generated by tag interacts with the magnetic field generated by active device. The chip inside the active device decodes the radio field to get the information in passive tag. Two powered devices can also participate in this one way communication, similarly as active RFID tags.
- NFC Two Way Communication: There should be two powered devices involved in this communication. When a device sends information, it becomes active and while receiving, it behaves as a passive device. So both devices act as active as well as passive while exchanging information. An active NFC device can communicate to single target at a time that means broadcasting of messages to multiple targets over NFC is not possible. NFC devices other then sender and target, ignore the communication completely.
Communication Modes of NFC:
- Passive Communication Mode: Initiator provides the carrier field, target device responds by modulating the existing field. In this, target device may need to draw operating energy via the field generated by initiator.
- Active Communication Mode: Initiator and target both communicate by generating their own fields. While receiving the data, device needs to deactivate its own field. In this, both the devices have their own power sources.
Modes of Operation:
- Read/Write Mode: An NFC device reads a tag.
- Peer-to-Peer Mode: Two NFC devices exchange information.
- Card Emulation Mode: NFC device emulates a smartcard.
NFC Standard and Specifications:
- In 2004, Nokia, Sony and Philips came together to establish a standard for NFC communication technology. Now about 140 companies are participating in the same cause via NFC forum.
- NFC is a set of short range wireless technologies. Theoretical working distance with compact standard antennas is up to 20 cm, but practically it limits to 4cm or less.
- NFC operates at 13.56MHz. This is the frequency used for transmission of data across NFC.
- NFC devices support data transmission speed between 106 kilobits per second and 424 kilobits per second. Currently used data rates are – 106, 212 and 424 kilo bits per second.
- NFC uses two different codings to transfer data. Modified Miller coding with 100% modulation is used when we transfer at 106 Kbit/s. In other cases, Manchester coding with 10% modulation ratio is used.
- NFC tags currently offer between 96 and 4,096 bytes of memory.
In smartphone era, using NFC we can make our smartphones a replacement for all our cards. To make payments, to verify your identity, to access your rewards and to know your remaining credit limit only smartphone with a NFC chip and a trigger application is enough. Google Wallet is the most famous application which is enabling you to do that. They store your card details, your personal identification details and other related details as your reward points, limits etc. Whenever you want to use your NFC supported smartphone to do any of the above mentioned tasks, you just need to place it near the NFC reader, start the application and all the necessary information will be transferred from your phone to the reader and yeah, now you are living with a lighter wallet.
For quick data transfers as contacts or song playlists exchange, you just need to place the participating smartphones close enough and you are done. NFC makes you more efficient in the usage of social media. File sharing is easy and it enables you to join multi-player games too easily.
Limitations and comparison with the close competitor “Bluetooth”:
- Although we have Bluetooth and Wi-Fi with a wider range of working distance, NFC is a short range favorite.
- You need pairing for Bluetooth and Wi-Fi. NFC requires no pairing.
- NFC is slow, seek less power and less setup time when compared with Bluetooth.
- NFC’s maximum data transfer rate is slower than that of Bluetooth v2.1.
- NFC consumes low power similarly as Bluetooth v4.0 low energy protocol but consumes more if used with one unpowered device.
- NFC is compatible with existing passive RFID infrastructures unlike Bluetooth.
- Short distant action is a major drawback of NFC.
- As radio frequencies are in picture, so security is a concern with NFC.