What Is Near Field Communications?

Near Field Communication (NFC) is an emerging technology. Devices that use NFC technology (such as mobile phones) can exchange data when they are close to each other. It is based on contactless radio frequency identification (RFID). ) And the interconnection and integration technology evolved. By integrating the functions of inductive card reader, inductive card and point-to-point communication on a single chip, the mobile terminal is used to implement mobile payment, electronic ticketing, access control, mobile identity recognition, anti-counterfeiting And other applications.
Near field communication

Chinese name: Near field communication
Foreign name: Near Field Communication ^[1]

Type: Short-distance high-frequency wireless communication technology
English abbreviations: NFC

Introduction to Near Field Communication

NFC Chinese is called near field communication technology. NFC is developed on the basis of non-contact radio frequency identification (RFID) technology and wireless interconnection technology. It provides a very safe and fast communication method for various electronic products that are increasingly popular in our daily life. The "near field" in the Chinese name of NFC refers to radio waves near the electromagnetic field. Because radio waves are actually electromagnetic waves, they follow Maxwell's equations. The electric and magnetic fields alternate from one transmitting antenna to the receiving antenna in the process of energy conversion, and they mutually enhance each other during the conversion. For example, the radio used in our mobile phones Signals are propagated using this principle. This method is called far-field communication. Within 10 wavelengths of electromagnetic waves, the electric and magnetic fields are independent of each other. At this time, the electric field is not significant, but the magnetic field can be used for short-distance communication, which we call near-field communication. ^[2]

The near field communication service combines near field communication technology and mobile communication technology, and realizes various functions such as electronic payment, identity authentication, ticketing, data exchange, anti-counterfeiting, and advertising. It is a new type of service in the field of mobile communication. The near-field communication service has enhanced the functions of mobile phones, gradually made consumer behavior electronic, and established a new type of user consumption and business model.

The application of NFC technology has received wide attention worldwide. Telecommunications operators at home and abroad, mobile phone manufacturers and other different roles have carried out application pilots, and some international associations have also actively carried out standardization work. According to relevant industry predictions, mobile phone applications based on near field communication technology will become the next killer application for mobile value-added services. ^[3]

Near field communication technology background

According to relevant information, around 2003, Sony Corporation and then Philips Semiconductors (now NXP Semiconductors) cooperated to develop a more secure and faster based on non-contact RF card technology And compatible wireless communication 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 NFC technology, both parties submitted a draft standard to the European Computer Manufacturers Association (ECMA), which applied to become a near field communication standard and was quickly recognized as the ECMA.340 standard. Then, the ECMA submitted a standard application to ISO / IEC And finally recognized as the ISO / IECl8092 standard. ^[2]

Near field communication technology standards

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

On December 8, 2003, it passed the audit of ISO / IEC (International Organization for Standardization / International Electrotechnical Commission) and became an international standard. On March 18, 2004, it was recognized as an European standard by the European Computer Manufacturers Association (ECMA) and has passed The standards are listed in ISO / IEC 18092 (NFCIP-1), ECMA-340, ECMA-352, ECMA-356, ECMA-362, and ISO / IEC 21481 (NFCIP-2).
The near-field communication standard specifies the modulation scheme, encoding, transmission speed, and frame format of the RF interface of the near-field communication device, 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. It also defines Transmission protocols, including protocol initiation and data exchange methods.

Working principle of near field communication

NFC is a short-range 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, encoding and decoding methods, modulation schemes, and frame formats of radio frequency interfaces in detail for NFC devices. This standard also defines NFC transmission protocols, including startup protocols and data exchange methods. ^[2]

NFC working mode is divided into passive mode and active mode. In passive mode, the NFC initiating device (also called the master device) needs a power supply device. The master device uses the energy of the power supply device to provide the RF field and sends data to the NFC target device (also called the slave device). The transmission rate needs to be 106kbps. , 212kbps, or 424kbps. The slave 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 used to convert power into electricity, power the circuit of the slave device, receive data sent by the master device, and use load modulation To transfer slave device data back to the master device at the same speed. Because the slave device does not generate a radio frequency field in this working mode, but passively receives the radio frequency field generated by the master device, it is called a passive mode. In this mode, the NFC master device can detect a contactless card or NFC target device, and To establish a connection. ^[2]

In the active mode, both the initiator device and the target device must actively generate a radio frequency field when sending data to each other. Therefore, they are called active mode. They both need power supply equipment to provide the energy to generate the radio frequency field. This communication mode is the standard mode for peer-to-peer network communication, and can obtain very fast connection rates. ^[2]

Main application forms of near field communication

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: point-to-point communication mode, reader mode, and NFC card simulation mode. ^[2]

Near-field communication point-to-point form

Point-to-point mode, in which two NFC devices can exchange data. For example, multiple digital cameras and mobile phones with NFC functions can be wirelessly interconnected using NFC technology to realize data exchange such as virtual business cards or digital photos. ^[2]

For the point-to-point form, the key point is to connect two devices with NFC function, so that the data transmission between the points can be realized. By taking the point-to-point form as the premise, NFC-enabled mobile phones and computers and other related devices can truly achieve point-to-point wireless connection and data transmission, and in subsequent related applications, not only local applications but also network applications. Therefore, the application of point-to-point form plays a very important role in the rapid Bluetooth connection between different devices and its communication data transmission. ^[4]

NFC reader mode

Read / write mode. In this mode, the NFC device is used as a contactless reader. For example, a NFC-enabled mobile phone plays the role of a reader when interacting with tags, and a NFC-enabled mobile phone can read and write tags that support the NFC data format standard. ^[2]

NFC communication in card reader mode is used as a contactless card reader, which can read related information from exhibition information electronic tags, movie posters, advertising pages, etc. NFC phones in card reader mode can collect data resources from TAGs and complete information processing functions according to certain application requirements. Some application functions can be completed directly locally, and some need to be completed in conjunction with mobile communication networks such as TD-LTE. NFC-based application areas based on the reader mode include advertising reading, ticket reading, cinema ticket sales, etc., such as TAG tags behind movie posters. At this time, users can bring a mobile phone that supports the NFC protocol to obtain movie information. Connect to buy movie tickets. The card reader NFC mode can also support the acquisition of bus station information and tourist attraction map information, improving the convenience of people's travel traffic. ^[4]

Near field communication card simulation form

Simulation card mode. This mode is to simulate a device with NFC function as a tag or contactless card. For example, an NFC-enabled mobile phone can be read as an access control card or bank card. ^[2]

The key of card simulation is to simulate the device with NFC function to make it a contactless card mode, such as bank card and access control card. This form is mainly used in contactless mobile payment such as shopping malls or transportation. In the specific application process, users only need to bring their mobile phones or other related electronic devices close to the card reader, and enter the corresponding password to enable the transaction to be completed. . For the card in the card simulation form, the key is to implement the power supply processing through the RF domain of the contactless reader, so that the NFC device can continue to work even without power. In addition, for the application of card simulation, it can also collect data in related devices with NFC function, and then transfer the data to the corresponding processing system for related processing. Moreover, this form can also be applied to the banned system and local payment And other aspects. ^[4]

Near-field communication characteristics

Near field communication is a short-range wireless communication technology developed based on RFID technology. Like RFID, near-field communication information is also transmitted through the electromagnetic induction coupling of the radio frequency part of the frequency spectrum, but there is still a big difference between the two. The transmission range of near field communication is smaller than that of RFID. The transmission range of RFID can reach 0 ~ 1m, but because of the unique signal attenuation technology adopted by near field communication, compared with RFID, near field communication has low cost, high bandwidth and energy consumption. Inferior characteristics.

The main characteristics of near field communication technology are as follows:
(1) Wireless communication technology for secure communication at short distances (within 10 cm).
(2) RF frequency: 13.56MHz.
(3) RF compatibility: ISO 14443, ISO 15693, Felica standards.
(4) Data transmission speed: 106kbit / s, 212 kbit / s, 424kbit / s.

NFC Comparison of near field communication NFC with other technologies

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, communication distance is 0 ~ 20cm (actually most products are within 10cm), and the transmission rate can be 106kbit / s, 212kbit / s, 424 kbit / s and 848kbit / s. In addition to NFC, short-range wireless communication technologies mainly include technologies such as radio frequency identification (RFID), Bluetooth, ZigBee, infrared, and Wi-Fi. Each of the above technologies has their own characteristics and advantages. The following figure shows the performance comparison of NFC and six other short-range wireless communication technologies in the listed frequency bands. ^[5]

It can be seen that NFC technology has extremely high security, has performance advantages in short-range communication, and more importantly, low cost. Therefore, since its introduction in 2003, it has received the attention and support of many enterprises. ^[5]

The following analyses and compares the characteristics of each communication technology and NFC technology.

NFCRFID Comparison of Near Field Communication NFC and RFID

First, the working modes are different. NFC integrates the point-to-point communication function, the reader function and the contactless card function into one chip, while the RFID consists of a reader and a tag. NFC technology can both read and write, while RFID can only read and judge information. ^[2]

Second, the transmission distance is different. NFC transmission distance is much smaller than RFID. NFC transmission distance is only 10 cm. RFID transmission distance can reach several meters, even tens of meters. NFC is a close-range, private communication method. Compared with RFID, NFC has the characteristics of close distance, high bandwidth, low energy consumption, and high security. ^[2]

Third, the application areas are different. NFC is more widely used in the field of consumer electronics, and plays a huge role in access control, public transportation, and mobile payment. RFID is better at long-distance identification and is more used in production, logistics, tracking, and asset management. on. ^[2]

NFC Comparison of Near Field Communication NFC and Bluetooth

Both NFC and Bluetooth are short-range communication technologies. Compared to Bluetooth, which has been integrated into mobile phones very early and has become popular, NFC has only begun to be integrated into mobile phones in recent years, and so far has been integrated into only a few mobile phones. . ^[2]

First, the setup time is different, the NFC communication setup procedure is simple, and the communication setup time is short, only about 0.1s; while the Bluetooth communication setup procedure is relatively complicated, and the communication setup time is relatively long, which takes about 6s. ^[2]

Second, the transmission distance is different. The NFC transmission distance is only 10cm, while the Bluetooth transmission distance can reach 10m. But NFC is slightly better than Bluetooth in terms of transmission power consumption and security. ^[2]

Third, the transmission speed and working frequency are different. The working frequency of NFC is 13.56MHz, the maximum transmission speed is 424 Kbit / s, while the working frequency of Bluetooth is 2.4GHz, and the transmission speed can reach 2.1 Mbit / s. ^[2]

NFC Comparison of Near Field Communication NFC and Infrared

Compared with infrared transmission, NFC has a similar transmission distance, but is faster than infrared transmission. The maximum transmission speed of NFC is 424 Kbit / s, while the infrared transmission speed is about 100Kbit / s. The setup time of NFC is slightly faster than that of 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. NFC does not have this limitation; in addition, NFC is more secure and reliable than infrared. ^[2]

NFC NFC applications

As a near-field communication technology, NFC is widely used. NFC applications can be divided into four basic types. The following introduces and analyzes these four basic application types. ^[2]

Near field communication payment application

NFC payment mainly refers to the application of a mobile phone with NFC function to virtualize a bank card and a card. The application of NFC as a virtual bank card is called an open-loop application. Ideally, a mobile phone with NFC function can be used as a bank card for mobile phone consumption on POS machines in supermarkets and shopping malls, but it is currently not fully realized in China. The main reason is that NFC payment as an open-loop application has a tedious industry chain, and the game of the interests and industry structure of card merchants and solution providers is very complicated. As far as the current environment of domestic NFC open-loop applications is concerned, due to the game of various interests, NFC open-loop payment applications have missed the best time before mobile payment such as Alipay and WeChat payment become popular. Develop it separately. After the development of NFC open-loop payment, only by seeking to connect and bind with Alipay and WeChat Pay, as the authentication means of Alipay and WeChat Pay, will it be possible to occupy a place in future mobile payments. The application that NFC virtualizes into a card is called a closed-loop application. At present, the development of closed-loop applications of NFC in China is not ideal. Although the NFC function of mobile phones has been opened in some cities' public transport systems, it has not been popularized. The basic reason is that the card-based card system has a card-issuing profit, and system integrators and operators (transit groups and schools, etc.) can obtain rich profits on card issuance. Therefore, Xiaomi and Huawei are currently piloting mobile phone NFC bus card functions in some cities, but both still need to open service fees. However, as the popularization technology of NFC mobile phones continues to mature, the card system will gradually support the application of NFC mobile phones. The prospect is optimistic, but the process is destined to be tortuous. ^[2]

Near field communication security application

The application of NFC security is mainly to virtualize mobile phones into access cards, electronic tickets, and so on. The NFC virtual access card is to write the existing access card data into the mobile phone's NFC. This way, the smart phone can be used to achieve the access control function without using a smart card. This not only facilitates the configuration, monitoring and modification of the access control, but also enables remote modification. And configuration, such as temporary distribution of vouchers when needed. The application of the NFC virtual electronic ticket is that after the user purchases the ticket, the ticket sales system sends the ticket information to the mobile phone. A mobile phone with NFC function can virtualize the ticket information into an electronic ticket. You can swipe the phone directly during the ticket check. The application of NFC in security systems is an important area for NFC applications in the future, and the prospect is very broad. Because in this area can directly bring economic benefits to the technology users, giving them more incentive to upgrade existing equipment and technology. Because the use of mobile phone virtual cards can reduce the use of access control cards or magnetic card tickets, directly reduce the cost of use, in addition, you can appropriately increase the degree of automation, reduce personnel costs and improve efficiency. ^[2]

NFC tag application

The application of the NFC tag is to write some information into an NFC tag. The user only needs to swipe the NFC tag on the NFC tag to obtain the relevant information immediately. For example, merchants can put NFC tags containing posters, promotional information, and advertisements at the door of the store. Users can use NFC phones to obtain relevant information according to their needs, and can log in to social networks and share details or good things with friends. Although the application of NFC tags is very convenient and the cost is low, but the current popularity of mobile networks and the gradual popularity of two-dimensional codes, the application prospects of NFC tags are not optimistic. Because compared with NFC tags, QR codes only need 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 can easily replace the application of NFC tags. ^[2]

Near field communication service characteristics

In recent years, NFC technology has received more and more attention, and services developed based on NFC technology have gradually penetrated into all aspects of people's lives.

Because NFC technology-based services transmit data mainly based on the frequency of 13.56MHz, the transmission distance is short. And the information transmission based on NFC technology belongs to the triggered information transmission, the information interaction time is very short, and a lot of time in the operation process belongs to the millisecond level. Therefore, according to the characteristics and advantages of NFC technology, the basic form of NFC services mainly has the following characteristics. ^[6]

(1) Short: The communication distance is short. The communication distance based on NFC is generally within 10cm, which is generally within reach of human hands. ^[6]

(2) Frequency: As a short-range wireless communication technology, although it is not a new technology, it has developed rapidly at home and abroad in the past two years, and NFC applications represented by mobile payments have gradually penetrated into people's daily lives. In life, therefore, the use of NFC-oriented services will become more frequent. ^[6]

(3) Fast: NFC-based information transmission is triggered information transmission. Although the transmission rate is not high, it often requires information exchange within a short period of time. Therefore, it is different from other communication services. For NFC services, fast transmission is required. deal with. ^[6]

It is precisely because NFC technology-based services have short operating distances, frequent operations, and fast operating processes. Therefore, when developing NFC-oriented services, the following limitations are brought about. ^[6]

(1) Regional limitations: NFC technology has a short operating distance. It is mainly to establish point-to-point data transmission between devices. Unlike ordinary wireless transmission, a large-scale transmission network is required. Therefore, each region can establish relatively independent services. System and transmission system, and the current status of the current NFC business also proves this point. For example, the existing model of the bus system is that each city is a relatively independent business system, and cities cannot form interoperability between cities. ^[6]

(2) Industry limitations: The entry barrier for NFC business is relatively low. Various industries can easily set up an NFC system for a specific business according to their own needs and conduct business operations on their own. However, the lack of uniform industry standards among various industries also leads to interoperability problems. ^[6]

(3) Business diversity: For users, the NFC service is a good bridge between users 'real life and virtual life, and users' real life is often not restricted by regions and industries. ^[6]

NFC Near field communication NFC charging technology

Based on the current overall situation of NFC technology patent applications in wireless charging, its technology development trend is basically consistent with NFC technology. Due to the shortcomings of NFC wireless communication technology, the transmission power is very small, and there are disadvantages in charging applications. Therefore, NFC wireless charging technology lags even behind the development of NFC technology.

NFC technology generally realizes its application through the terminal. The power endurance characteristics of wireless terminals also belong to a major focus of research. Based on this, wireless charging technology has emerged as the times require. For NFC wireless charging technology, on the one hand, it is related to improvements in signature, authentication, and power efficiency derived from the characteristics of NFC technology itself. On the other hand, because other wireless charging technologies, such as those based on electromagnetic induction and magnetic resonance, are relatively mature and complete, improvements in other wireless charging research areas have also been applied to NFC charging technologies, such as antenna form adjustments and electromagnetic shielding. Problem research.

The development direction of NFC charging antennas is generally in the direction of reducing interference, increasing communication distance, and miniaturization. Due to factors such as miniaturization and the shape of terminal equipment, ring NFC antennas have been widely used for a long time. With the further development of antenna technology after 2010, some three-dimensional structures and special geometric shapes of antennas have gradually been applied to NFC. charging. In response to the needs of multiple frequency bands for terminal equipment, the antenna has a double-structured ring NFC antenna in shape improvement. However, for this problem, matching circuits are more used for adjustment, and the adjustment direction of the matching circuit is more diversified. To reduce the size of the antenna, enhance the signal, reduce the effect of interference. Early management strategies were basically designed to reduce power consumption. However, with the advent of NFC charging technology, various strategies for power monitoring were transferred to NFC charging strategies. In the technology of monitoring the electrical characteristics of the terminal equipment and reasonably arranging the charging, a technical solution for monitoring the residual power was quickly proposed, and the technical solution for starting the charging based on the distance between the terminal device and the charger appeared later, and both were in The year was extended to the field of multi-terminal. This is relatively consistent when compared with other wireless charging technologies. In view of other technical parameters such as current and temperature that can be monitored, a technical solution for protecting the terminal is proposed. ^[5]