1 Technical introduction NFC is a new technology that has evolved on the basis of radio frequency identification (RFID) and interconnection technology. It is a short-range wireless communication technology standard. It integrates contactless card readers, contactless smart cards and point-to-point functions on a single chip. It runs in the frequency range of 13.56MHz and can establish connections between devices within a range of about 10cm. The transmission rate can be 106kbit / s, 212kbit / s, 424 kbit / s, it can be increased to more than 848kbit / s in the future NFC terminal has three working modes: (1) In active mode, the NFC terminal acts as a card reader and actively sends out its own RF field to identify and read / write other NFC devices; (2) In passive mode, the NFC terminal can be simulated as a card to be read / written, and it only responds passively in the RF field emitted by other devices; (3) In two-way mode, both parties actively send out RF fields to establish point-to-point communication. NFC is used to quickly establish wireless communication between various devices within a short distance. It can be used as a virtual connector, which can meet the data exchange between any two wireless devices. It can also initialize the original wireless protocols such as Bluetooth and 802.11, so that the device can communicate over a longer distance or transmit data at a higher rate. Therefore, in addition to information transmission, NFC devices can be used as a secure gateway in the connected world, allowing users to store or receive various information at any time, whether at home or on the move. As long as the two NFC devices are close together, they will automatically start the network communication function, and the user does not need to set up an installation program separately, so as to realize the aforementioned contactless mobile payment, identification and other electronic wallet and ID card functions. NFC technology conforms to the ISO18092 and ISO21481 standards of the International Organization for Standardization, is compatible with the ISO14443 standard of wireless smart cards, and complies with the EMCA-340, 352, and 356 standards of the European Computer Association. NFC is compatible with the top two in the field of contactless smart cards-Philips' MIFARE technology and Sony's FeliCa technology. Based on the former, about 1.2 billion smart cards have been deployed, and the latter has also deployed about 170 million. This makes NFC technology fully equipped with the characteristics of low power, low price, and compatibility that future short-range wireless interconnection devices should have, and makes NFC a very competitive technology in the field of short-range wireless interconnection. 2 Application classification and status 2.1 Application classification The application of NFC technology can be divided into five categories: (1) Touch and Go, such as access control, tickets and tickets, etc. The user can close the device storing the ticket or gate control password to the card reader, and it can also be used for logistics management. (2) Touch and Pay (Touch and Pay), such as contactless mobile payment, the user can make payment by placing the device close to the POS machine with embedded NFC module and confirm the transaction. (3) Touch and Connect, such as connecting two NFC devices (such as mobile phone and laptop in Figure 1), to perform peer-to-peer (Peer-to-Peer) data transmission, such as downloading music, mutual transfer of pictures and Exchange address book, etc. Figure 1 NFC point-to-point communication between mobile phones and laptops (4) Touch and Explore, users can connect NFC mobile phones to smart public phones or posters with NFC function on the street to browse traffic information, etc. (5) Download and touch (Load and Touch), users can receive or download information through GPRS network for payment or access control functions, as mentioned above, users can send SMS in a specific format to the mobile phone of the housekeeping attendant to control the housekeeping attendant to enter and exit permission. 2.2 Application status at home and abroad The NFC Forum, a non-profit industry association created by Nokia, Philips and Sony in 2004, currently has 11 sponsoring members including Samsung, Microsoft, Visa, etc., and its total number of members has exceeded 100. Leading operators, mobile phone manufacturers, chip manufacturers, smart card manufacturers, banks and credit card organizations (see Table 1). Table 1 Some global NFC mobile phone test projects In Japan, since NTT DoCoMo launched the mobile wallet business based on Felica technology in July 2004, its user base can already be described as "large", and POS machines that support Felica are already everywhere on the streets of Japan. After several upgrades, Felica mobile phones have been widely used in transactions, identity recognition, and access control management. The huge transaction volume prompted NTT DoCoMo to establish a financial services department by acquiring a 34% stake in Sumitomo Mitsui Credit Card Company. In Hong Kong, China, Felica technology is used on the "Octopus" card with electronic wallet and identification function, and the number of cards issued has reached ten million. Felica technology is also widely used in Singapore. In the EU, the StoLPaN (Store LogisTIcs and Payment with NFC) project, jointly invested by the European Commission and the Information Society Technology (IST) project, Motorola and other companies, and Budapest University and other universities, is also planned to be released in the summer of 2007 Version technical specifications and applications, and demonstrate the application of NFC in transportation and closed payment systems. The project aims to develop an open commercial and technical framework for NFC-based services and promote the deployment of NFC-based mobile applications in many industries. 　　
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