1 RFID Technology
1.1 RFID System Architecture
RFID is a new non-contact automatic identification technology, called electronic tag. This technology does not involve manual intervention and physical contact restriction, and is extremely important for the establishment and development of computer environment. In order to achieve automatic identification of target objects, the technology uses coupled transmission and radio frequency signals. The foundation of RFID is chip technology and radio technology. The antenna, tag and reader constitute the RFID system. The technology has the advantages of less restriction on working environment, recognition of high-speed moving targets, recognition of N targets and simple operation. In the structure of RFID system, electronic tag is called tag for short, and it is also called radio frequency tag. Control logic and radio frequency circuit are installed in tag. With the development of more and more advanced integration technology, the integrated chip in tag is smaller, but its function is more comprehensive and powerful. Interrogator is also called reader. Its communication operation electronic tag is realized by RFID protocol. Digital control unit and radio frequency module constitute the reader. When a tag appears in the magnetic field, it receives the radio frequency signal, which comes from the reader, and the product information stored in the chip comes from the energy obtained by the induced current. The information is read and decoded by the reader, and the processing of related data is sent to the central information system. The system framework is shown in Figure.
1.2 Types of RFID Technology
According to the different frequencies, RFID technology system is mainly divided into three types: high frequency system, intermediate frequency system and low frequency system. Various shapes and low cost belong to the characteristics of low-frequency system tags, which are located in low-frequency systems with frequencies of 100-500 kHz. The shortcomings of low-frequency system itself are: lack of effective and stable direction of reading antenna; unsatisfactory reading speed; relatively short reading distance; less data storage, etc. Therefore, it is mainly used in environments with low technical requirements, such as access control system. The working frequency of IF system is 10-15 MHz. Compared with low frequency system, IF system increases reading distance, and its tag memory is relatively large, which achieves medium reading speed. However, the disadvantages are that the reading antenna is strong, the direction is insufficient, the cost of reader and tag is high. Therefore, the working environment of smart card and access control system is suitable for the application of IF system. Soft substrate is the tag shape of high-frequency system. Compared with the former two systems, the high-frequency system further enlarges the tag memory. The advantages of the high-frequency system are fast reading speed and long distance. The disadvantage is the high cost of reader and label. The high frequency system is applied in the retail system and the monitoring system of train wagons.
1.3 Label Type
Labels are generally divided into two categories, one is passive label, the other is active label. Passive tags are inexpensive and flexible in appearance. They are powered by readers. Through coupling, the power of tag chips comes from the energy of readers, while active tags integrate power modules in tags.
2 Internet of things
With the continuous improvement of social economy and science and technology level in our country, new information technology has been widely used. After further extending the traditional Internet, the Internet of Things has come into being. At the same time, the exchange of information between any object has been realized. It can be said that the Internet of Things occupies a very critical position. In order to obtain specific information, the Internet of Things relies on sensor devices and RFID technology.
Information transmission is in accordance with the agreement, and its organizational network is large. It can intelligently monitor and process various data information. Relying on advanced computer technology, monitoring and processing various data and information, function processing, accurate and timely transmission of information, reliable transmission, more rapid and convenient access to information, comprehensive perception and so on, all reflect the typical characteristics of the Internet of Things. Integrating application layer, information operation layer, information transmission layer and information collection layer is the hierarchical structure of the Internet of Things. Integrating application layer to analyze practical information problems, to provide a basis for decision-making and processing issues; Information operation layer is mainly to further analyze and process information, and break through the information platform, classify and manage information; Information transmission layer through the use of sensors, transfers and integrates the collected information. The collection information layer collects all kinds of data and information, uses advanced technology and methods to mark data and information, and transforms these data and information with the standard of automatic paste processing functional data. The key to analyze the hierarchical structure is to collect and process information. After the scientific application of RFID technology, the target object can be automatically and effectively identified, and finally the required data information can be obtained successfully.
3.Application of RFID Technology in Internet of Things
3.1 System Composition
The antenna, reader and tag are the three parts of the basic radio frequency identification system. The radio frequency signal is transmitted by the reader. After the energy is captured by the tag in the magnetic field, the communication between the reader and the reader is carried out. The information stored in the tag is read and decoded by the reader, and then transmitted to the management system and processed. As shown in Figure 2.
Wireless communication between reader and tag is realized by transmitting radio frequency signal, which is the function of antenna. The antenna is divided into fixed antenna, hand-held antenna, active antenna, passive antenna and so on. In practical application, the wavelength and size of the antenna are the same and consistent. For data transmission, the position and shape of antenna also play a very important role. From this point, it can be seen that for staff, the design and installation of antenna is of high technical content.
The main function of RFID reader is to recognize the target object. To accurately identify the target object, it is necessary to read and identify the memory data of the electronic tag. Through the radio frequency signal and coupling, the information transmission between the tag and the reader is contactless. Its working principle is as follows: transmitting the host read/write command to the tag, encrypting and processing the data transmitted by the host to the tag, and then transmitting the decrypted tag back to the host. The most important characteristic of reader is when the range of transceiver is large, but because the higher cost reader restricts the development of RFID system, the development trend of reader is reflected in low cost, convenience, small scale and so on.
Tagging transforms the target object into intelligent object, which is easy to monitor and track. Therefore, radio frequency card is also called electronic tag. It consists of chip and coupling element. The data carrier of RFID system is electronic tag. Communication between tag and reader can be realized by connecting antenna, so that tag identification code and data can be input and read out. According to the actual needs to design the shape of the tag,the tag memory data can be protected, not easy to damage the tag. Long time monitoring and tracking multiple fast moving targets, long service life, high data storage, small size and easiness to use are all the advantages of electronic tags. Electronic tags are microwave, ultra-high frequency, high frequency and low frequency tags according to different frequency atmosphere. Moreover, the passive and active systems are classified according to whether the tag is equipped with built-in batteries or not.
3.2 Practical Application
The application of RFID technology in security anti-counterfeiting, charging system and logistics management system are introduced as examples.
3.2.1 Applied to Security and Anti-counterfeiting
RFID technology can achieve fast scanning, so it is widely used in security and anti-counterfeiting, and its identification number is unique. Unlike traditional bar code scanning, RFID technology is not restricted by direction. It can detect target objects in magnetic field at the same time, which greatly improves work efficiency and is suitable for mass operation. Firstly, the application is not easily damaged and durable. With the application of RFID technology, the chip can store the information of goods, so it is not easy to be damaged. Traditional paper barcodes are vulnerable to environmental impact. Secondly, it has strong penetration. When the items are covered, the tag information can also be identified by using the penetrating RFID technology. In this case, the data storage capacity is large, compared with the traditional barcode, the amount of information carried by the RFID tag is much larger. Finally, it can be reused. With the application of RFID tags, data and information can be updated in time, and can be modified and used repeatedly. However, traditional barcode can not be modified and implemented
3.2.2 Applied to Toll Collection System
In today's Expressway Automatic Toll Collection system, RFID technology is widely applied. The radio frequency card is installed in the vehicle, the antenna is set up along the highway, and the electronic technology and modern information technology are used. The data are transmitted by electronic tags and antennas, and the charging data are processed after the vehicle is identified, so that the vehicle fee is automatically collected.
The application of radio frequency technology in automatic toll collection system has strong economic benefits, reduces labor costs, alleviates traffic congestion, improves vehicle passing rate and promotes work efficiency. Moreover, the technology is also applied in the access control system, such as electronic passport, parking card, access card, door card, etc. all belong to the radio frequency card, which can automatically identify the user's identity. In addition, RFID technology is also applied to the bus system card, which saves costs, facilitates operation and improves the efficiency of bus operation.
3.2.3 Applied to Logistics Management System
The following three aspects are discussed: Firstly, the application in automatic mail sorting system. RFID technology has been effectively applied in the sorting mail system of express business. When a large number of parcels enter the identification area, the non-contact characteristic of RFID technology is brought into full play, which not only improves the working accuracy effectively, but also greatly improves the sorting efficiency. Secondly, the application in container identification system. Mark the relevant data and information on the container label, such as quantity, category, location, etc. Location monitoring and tracking containers are used in RFID technology. When moving containers, tags can also receive changing information and data, and manage and monitor prohibited moving containers. Thirdly, the application of railway dispatching system. In order to detect the luggage and goods in the train and the information of the train running in real time, the reader is installed along the railway line.
After reasonably analyzing the acquired information, monitoring and tracking the operation of the train can effectively avoid the hidden dangers of dangerous goods in the vehicle and train collision accidents in operation.
With the steady development of science and technology in China, the Internet of Things (IOT), a large-scale organizational network, has also made unprecedented progress. In the Internet of Things, commodities and articles can communicate with each other without the participation of people. In fact, through the computer internet, we use radio frequency automatic identification technology, and share automatic identification information of interconnected goods. The technology premise of IOT operation is sensor equipment and RFID technology. RFID technology can identify the target object accurately, automatically and effectively. It can be realized by coupling transmission and the use of radio frequency signals. Antenna, reader and tag are important parts of radio frequency identification system. Among them, the antenna is the wireless communication between reader and tag by transmitting radio frequency signals; while the reader reads and identifies the memory data of the tag in order to recognize the target object; by tagging the target object, the tag achieves tracking and monitoring functions.