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    2021-10-21 17:41:23
    Near Field Communication (NFC) Explained: Working and Applications


    Ⅱ NFC technical standard
    Ⅲ NFC working principle 
    Ⅳ NFC working modes
     Comparison of NFC and other wireless technologies
     NFC applications


    Ⅰ Introduction

    NFC is developed on the basis of non-contact radio frequency identification (RFID) technology and combined with wireless interconnection technology. It provides a very safe and fast communication method for various electronic products that are becoming more and more popular in our daily lives. The "near field" in the NFC refers to radio waves near the electromagnetic field. Because radio waves are actually electromagnetic waves, they follow Maxwell’s equations. Electric and magnetic fields will always alternate energy conversion during the process of propagating from the transmitting antenna to the receiving antenna, and they will enhance each other during the conversion, such as the radio used in our mobile phones. The signal is propagated using this principle, and this method is called far-field communication. However, within 10 wavelengths of electromagnetic waves, the electric field and the magnetic field are independent of each other. At this time, the electric field does not have much meaning, but the magnetic field can be used for short-distance communication, which we call near-field communication.

    Near field communication business combines near field communication technology and mobile communication technology to realize multiple functions such as electronic payment, identity authentication, ticketing, data exchange, anti-counterfeiting, and advertising. Near-field communication services have enhanced the functions of mobile phones, making users' consumption behaviors gradually electronic, and establishing a new type of user consumption and business models.

    Ⅱ NFC technical standard

    Around 2003, Sony and Philips Semiconductors (now NXP Semiconductors) cooperated to develop a safer and faster technology based on non-contact RF card technology. After several months of research and development, the two parties jointly released a wireless communication technology compatible with the IS014443 contactless card protocol, named NFC (Near Field Communication), and the specific communication specification is called the NFCIP-1 specification. Not long after the release of the NFC technology, both parties submitted a draft standard to the European Computer Manufacturers Association (ECMA), applied to become a near field communication standard and was quickly recognized as the ECMA.340 standard, and then submitted a standard application to ISO/IEC with the help of ECMA. And it was finally recognized as the ISO/IEC18092 standard.

    Near field communication technology is a standard jointly developed by Nokia, Philips, and Sony. It promotes standardization under the framework of ISO 18092, ECMA 340, and ETSI TS 102 190. It is also compatible with the widely used ISO 14443, and the infrastructure of Type-A, ISO 15693, B, and Felica standard contactless smart cards.

    NFC module.jpg

    NFC module

    The near field communication standard specifies the modulation scheme, coding, transmission speed, and frame format of the radio frequency interface of the near field communication equipment in detail, as well as the initialization scheme and conditions required for data conflict control during the initialization process of the active and passive near field communication modes. In addition, it also defines the transmission protocol includes protocol activation and data exchange methods.

    Ⅲ NFC working principle 

    NFC is a short-distance high-frequency radio technology. The NFCIP-1 standard stipulates that the communication distance of NFC is within 10 cm, the operating frequency is 13.56 MHz, and the transmission speed is 106Kbit/s, 212Kbit/s, or 424Kbit/s. The NFCIP-1 standard specifies the transmission speed, codec method, modulation scheme, and frame format of the radio frequency interface of NFC devices in detail. This standard also defines the NFC transmission protocol, including the activation protocol and data exchange method.

    NFC working modes are divided into passive mode and active mode. In the passive mode, the NFC initiator device (also called the master device) needs a power supply device. The master device uses the energy of the power supply device to provide a radio frequency field and sends data to the NFC target device. The transmission rate needs to be 106kbps, 212kbps, or 424kbps. The target device does not generate a radio frequency field, so there is no need for a power supply device. Instead, the radio frequency field generated by the master device is converted into electrical energy to supply power to the circuit of the target device. The target device receives data sent by the master device and uses load modulation technology to transfer data from the device back to the master device at the same speed. Because the target device does not generate the radiofrequency field in this working mode, but passively receives the radiofrequency field generated by the master device, it is called passive mode. In this mode, the NFC master device can detect contactless cards or NFC target devices, and establish a connection.  

    In the active mode, both the initiator and the target device must actively generate a radio frequency field when sending data to each other, so it is called the active mode, and they both require a power supply device to provide energy to generate the radiofrequency field. This communication mode is a standard mode for peer-to-peer network communication and can obtain very fast connection rates.

    Ⅳ NFC working modes

    In order to be compatible with contactless smart cards, the NFC standard specifies a flexible gateway system, which is specifically divided into three working modes: peer-to-peer communication mode, reader/writer mode, and NFC card emulation mode.

    1.Peer-to-peer mode

    Two NFC devices can exchange data under peer-to-peer mode. For example, multiple digital cameras and mobile phones with NFC functions can use NFC technology for wireless interconnection to realize data exchange such as virtual business cards or digital photos.

    After taking the peer-to-peer mode as the premise, the NFC-enabled mobile phones and computers, and other related devices can truly achieve peer-to-peer wireless connection and data transmission, and in subsequent associated applications, it can be used not only for local applications but also for network applications. Therefore, peer-to-peer applications play a very important role in the rapid Bluetooth connection between different devices and the transmission of communication data.

    2.Reader/writer mode

    In read/write mode, the NFC device is used as a contactless reader. For example, a mobile phone that supports NFC plays the role of a reader when interacting with tags, and a mobile phone with NFC enabled can read and write tags that support the NFC data format standard.

    The NFC communication in card reader mode is used as a non-contact card reader, which can read relevant information from exhibition information electronic tags, movie posters, advertising pages, etc. NFC mobile phones in card reader mode can collect data resources from TAG and complete information processing functions according to certain application requirements. Some application functions can be directly completed locally, and some need to be combined with mobile communication networks such as TD-LTE. NFC application areas based on the card reader mode include advertisement reading, ticket reading, movie theater ticket sales, etc. For example, a TAG tag is affixed to the back of a movie poster.

    3.NFC card emulation mode

    NFC card emulation mode is to simulate a device with NFC function as a tag or contactless card. For example, a mobile phone that supports NFC can be read as an access card, bank card, etc.

    The key to the card emulation mode is to simulate the device with NFC function and turn it into a non-contact card mode, such as bank cards and access control cards. This mode is mainly used in non-contact mobile payments such as shopping malls or transportation. In the specific application process, users only need to put their mobile phone or other related electronic devices close to the card reader, and enter the corresponding password at the same time to complete the transaction. Regarding the card in the mode of card emulation, the key is to perform power supply processing through the RF domain of the contactless card reader, so that the NFC device can continue to work even if the NFC device has no power.

    Ⅴ Comparison of NFC and other wireless technologies

    The current short-range wireless communication technologies include RFID, Bluetooth, infrared, etc. NFC is a short-range high-frequency wireless communication technology that allows non-contact point-to-point data transmission between electronic devices. Its working frequency is 13.56MHz, the communication distance is 0-20cm (most products are within 10cm in fact), and the transmission rate can be 106kbit/s, 212kbit/s, 424 kbit/s, and 848kbit/s. In addition to NFC, NFC technology also mainly includes radio frequency identification (RFID), Bluetooth (Bluetooth), ZigBee (ZigBee), infrared, Wi-Fi, and other technologies. Each of the above technologies has its own characteristics and advantages.

    The following is an analysis and comparison of the characteristics of each communication technology and NFC technology.

    1.Comparison of NFC and RFID

    First, the working mode is different. NFC integrates peer-to-peer communication functions, reader functions, and non-contact card functions into a single chip, while RFID consists of two parts: a reader and a tag. NFC technology can both read and write, while RFID can only read and determine information.

    Second, the transmission distance is different. The transmission distance of NFC is much smaller than that of RFID. The transmission distance of NFC is only 10 cm. The transmission distance of RFID can reach several meters or even tens of meters. NFC is a short-distance private communication method. Compared with RFID, NFC has the characteristics of short distance, high bandwidth, low energy consumption, and high security.

    Third, the application areas are different. NFC is more used in the field of consumer electronics, playing a huge role in access control, public transportation, mobile payment, and other fields; RFID is better at long-distance identification and is more used in production, logistics, tracking, and asset management.

    2.Comparison of NFC and Bluetooth

    Both NFC and Bluetooth are short-range communication technologies. Compared with Bluetooth, which was integrated into mobile phones for a long time and has been popularized, NFC has only been integrated into mobile phones in recent years.

    First, the establishment time is different. The NFC communication setup procedure is simple, and the communication establishment time is very short, only about 0.1s; while the Bluetooth communication setup procedure is relatively complicated, and the communication establishment time is longer, about 6s.

    Second, the transmission distance is different. The NFC transmission distance is only 10cm, while the Bluetooth transmission distance can reach 10m. However, NFC is slightly better than Bluetooth in terms of transmission power consumption and security.

    Third, the transmission speed and operating frequency are different. The NFC operating frequency is 13.56 MHz and the maximum transmission speed is 424 Kbit/s, while the Bluetooth operating frequency is 2.4 GHz and the transmission speed can reach 2.1 Mbit/s.

    3.Comparison of NFC and infrared transmission

    Compared with infrared transmission, NFC has the same transmission distance but is faster than infrared transmission. The maximum transmission speed of NFC can reach 424 Kbit/s, while the transmission speed of infrared is about 100Kbit/s. The setup time of NFC is slightly faster than infrared, the setup time of NFC is 0.1s, and the setup time of infrared transmission is 0.5s. Infrared transmission must be strictly aligned to transmit data, and there must be no obstacles in the middle, while NFC has no such limitation; in addition, NFC is more secure and reliable than infrared.

    Ⅵ NFC applications


    NFC for payment.jpg

    NFC for payment

    NFC payment mainly refers to applications where a mobile phone with NFC function is virtualized into a bank card, all-in-one card, etc. The application of NFC virtualized into a bank card is called an open-loop application. Ideally, a mobile phone with an NFC function can be used as a bank card to swipe mobile phone consumption on POS machines in supermarkets and shopping malls, but this is not yet fully realized. The main reason is that NFC payment as an open-loop application has a tedious industrial chain, and the game between the interests of card vendors and solution providers and the industrial structure is very complicated. The application of NFC virtualized into a one-card card is called a closed-loop application. At present, although the NFC function of mobile phones has been opened in the public transportation system of some cities, it has not been popularized. The fundamental reason is that the all-in-one card system with cards as the carrier has a profit for issuing cards, and system integrators and operators can obtain huge profits from issuing cards. However, as the popularization technology of NFC mobile phones continues to mature, the one-card system will gradually support the application of NFC mobile phones. The prospect is optimistic, but the process is destined to be tortuous.

    2.Identity and access tokens

    NFC applications.jpg

    NFC applications

    NFC identity and access tokens are mainly to virtualize mobile phones into access control cards, electronic tickets, etc. NFC virtual access control card is to write the existing access control card data into the NFC of the mobile phone so that the access control function can be realized by using the mobile phone without using a smart card. This is not only convenient for the configuration, monitoring, and modification of the access control but also can be remotely modified. And configuration, such as temporarily distributing credential cards when needed. The NFC virtual electronic ticket application is that after the user purchases the ticket, the ticketing system sends the ticket information to the mobile phone. The mobile phone with the NFC function can virtualize the ticket information into an electronic ticket, and you can directly swipe the mobile phone during ticket checking.

    3.NFC tags

    The application of the NFC tag is to write some information into an NFC tag, and the user only needs to wave the NFC tag with an NFC mobile phone to get the relevant information immediately. For example, businesses can put NFC tags containing posters, promotional information, and advertisements at the entrance of the store, and users can use NFC mobile phones to obtain relevant information according to their needs and can log in to social networks and share details or goodies with friends. Although the application of NFC tags is very convenient and the cost is very low, the application prospects of NFC tags are not optimistic due to the popularization of mobile networks and the gradual popularity of QR codes. Because compared with NFC tags, the QR code only needs to be generated and printed into a small image, which can be said to be almost zero cost. The information provided is as rich as NFC, and it is easy to replace the application of NFC tags.

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