1、 Introduction to RFID Technology

Radio Frequency Identification Technology (RFID) is a non-contact automatic identification technology that has matured since the 1980s. It automatically identifies target objects and obtains relevant data through RF signals. Conceptually, RFID is similar to barcode scanning. For barcode technology, it attaches the encoded barcode to the target and uses a dedicated scanning reader to transmit the information from the strip magnet to the scanning reader using photoelectric signals; RFID uses a special RFID reader writer and a special RFID unit that can be attached to the target, and uses RF signals to transmit information from the RFID unit to the RFID reader writer. The RFID unit contains all kinds of relevant information about the target, such as the name of the target, the starting and ending places of the target transportation, the transit place, the specific time when the target passes through a certain place, etc., and can also load indicators such as temperature. RFID units, such as labels and cards, can be flexibly attached to various items from vehicles to cargo chassis.

(1) Basic RFID system composition:

Reader: a device for reading (sometimes writing) label information, which can be designed as hand-held or fixed;

Antenna: transmit RF signal between tag and reader.

Generally, electronic data in an agreed format are stored in electronic labels. In practical applications, electronic labels are attached to the surface of objects to be identified. The reader can read and identify the electronic data stored in the electronic tag without contact, so as to achieve the purpose of automatic identification of the body. Usually, the reader is connected to the computer, and the read label information is transferred to the computer for further processing. (In addition to the above basic configuration, the corresponding application software shall also be included)

Tag: It is composed of coupling components and chips. Each tag has a unique electronic code and is attached to the object to identify the target object; Each label has a globally unique ID number - UID, which is placed in the ROM when the chip is made and cannot be modified. The user data area (DATA) is for users to store data, which can be read, written, overwritten, and added. There are three types of reader writer operations on labels:

Identify: read UID;

Read: read user data;

Write: write user data

(2) Working principle of RFID system:

In the practical application of RFID system, the electronic tag is attached to the surface of the object to be identified, and the electronic data in the agreed format is stored in the electronic tag. The reader can read and identify the electronic data stored in the electronic tag without contact, so as to achieve the purpose of automatic identification of objects. The reader sends a RF signal of a certain frequency through the antenna. When the tag enters the magnetic field, it generates an induced current to obtain energy, and sends out its own coding and other information. After being read and decoded by the reader, it is sent to the computer host for relevant processing.

(3) Operating frequency of RFID system:

Usually, the frequency used by the reader when sending is called the working frequency of the RFID system. Common operating frequencies include low frequency 125kHz, 134.2kHz and 13.56MHz. Low frequency system generally refers to its operating frequency less than 30MHz. Typical operating frequencies include 125KHz, 225KHz

High frequency system generally refers to its operating frequency greater than 400MHz. Typical operating frequency bands include 915MHz, 2.45GHz, 5.8GHz, etc. High frequency systems are also supported by numerous international standards in these frequency bands. The basic characteristics of the high-frequency system are that the cost of electronic tags and readers is high, the amount of data stored in the tags is large, the reading distance is long (up to several meters to more than ten meters), the performance of adapting to high-speed movement of objects is good, the shape is generally card shaped, and the reading antenna and electronic tag antenna have strong directionality.

(4) RFID tag type

RFID tags are divided into passive tags and active tags. Active tags are powered by batteries. They are bulky when the reading/writing distance is long, and cost more than passive tags. Also known as active tags, they generally have a long reading distance. The disadvantage is that the battery cannot be used for a long time, and the battery needs to be replaced when the energy is exhausted.

After receiving the microwave signal from the reader (readout device), the passive electronic tag converts part of the microwave energy into DC power for its own work. Generally, it can be maintenance free, low cost, and has a long service life. It is smaller and lighter than the active tag. The distance between reading and writing is closer, also known as the passive tag. Compared with the active system, the passive system is slightly limited in the reading distance and the speed of the object movement.

According to whether the stored information has been rewritten, labels are also divided into read only labels and read and write labels. The information in the read-only labels will be written into information during the production of integrated circuits, which cannot be modified in the future and can only be read by special equipment; The read-write tag writes the saved information into its internal storage area. If it needs to be rewritten, it can also be rewritten by special programming or writing equipment. Generally, it takes much more time to write information into an electronic tag than to read it. The time spent on writing is seconds, and the time spent on reading is milliseconds.

3. RFID technology features and advantages

RFID is a flexible application technology that is easy to control, simple and practical, and especially suitable for automatic control. No manual intervention is required for identification. It can support both read-only and read-write working modes without touching or aiming; It can work freely in various harsh environments: short-range RF products are not afraid of oil stains, dust pollution and other harsh environments, and can replace barcode, for example, they can be used to track objects on the assembly line of the factory; Long distance RF products are mostly used in transportation, and the identification distance can reach tens of meters, such as automatic toll collection or vehicle identification. Its unique advantages are beyond other recognition technologies. It mainly includes the following aspects:

Easy and fast reading: data can be read without light source, even through the outer package. The effective recognition distance is larger. When the active label with its own battery is used, the effective recognition distance can reach above;

Fast identification speed: once the label enters the magnetic field, the reader can read the information in it instantly, and can process multiple labels at the same time to achieve batch identification;

Large data capacity: the two-dimensional barcode (PDF417) with the largest data capacity can only store 2725 numbers at most; If it contains letters, the storage capacity will be less; RFID tags can be expanded to tens of K according to the needs of users;

Long service life and wide application range: its radio communication mode enables it to be used in highly polluting and radioactive environments such as dust and oil pollution, and its closed packaging makes its service life much longer than the printed barcode;

The tag data can be dynamically changed: the programmer can write data to, which gives RFID tags the function of interactive portable data files, and the writing time is less than that of printing barcodes;

Better security: it can not only be embedded or attached to products of different shapes and types, but also set password protection for reading and writing label data, so it has higher security;

Dynamic real-time communication: The tag communicates with the interpreter at a frequency of 50-100 times per second, so as long as the object attached to the RFID tag appears in the effective identification range of the interpreter, its position can be dynamically tracked and monitored.

2、 Application of RFID Technology in Intelligent Transportation

Nowadays, with the development of social economy and the acceleration of urbanization, the population is rapidly migrating to the city. The number of population and vehicles is growing continuously, but the limited available land and economic factors restrict the expansion and capacity of urban roads, which inevitably brings a series of traffic problems. Nowadays, all large and medium-sized cities around the world are plagued by traffic problems. Traffic congestion causes people to spend a lot of precious time on the road and vehicles every day. It also causes commercial vehicles to be delayed in transportation, increasing transportation costs. The traffic accident rate is also rising, which will bring huge casualties and economic losses every year. According to the prediction of relevant departments in the United States, by 2020, the economic losses caused by traffic accidents in the United States will exceed 150 billion dollars annually, while the economic losses caused by traffic congestion in Tokyo, Japan, are 123 billion dollars annually. In order to solve the increasingly serious traffic problems, governments of all countries have taken various measures, such as imposing heavy taxes on cars to limit the number of cars, implementing traffic control, etc. to strengthen management. However, after various attempts and huge management costs, it is still difficult to fundamentally improve the traffic conditions.

People gradually realize that the traffic system is a complex and comprehensive system. It is difficult to solve the traffic problem from the perspective of roads or vehicles alone. We must integrate vehicles and roads and consider how to improve the utilization of road resources under the condition of limited road resources, which is the key to solving the problem. At the same time, the rapid development and wide application of information technology since the late last century also provide effective technical means to support the above solutions. In this context, the concept of intelligent transportation has been applied and become a research and application hotspot.

The so-called intelligent transportation system refers to a real-time, accurate and efficient comprehensive transportation management and control system that organically applies advanced information technology, electronic communication technology, automatic control technology, computer technology and network technology to the entire transportation management system. It is composed of several subsystems. Through system integration, roads, drivers and vehicles are organically combined to strengthen the relationship between the three. With the help of intelligent technology of the system, the information of various traffic modes and road conditions are registered, collected and analyzed, and these information are provided to the people in need in real time through remote communication and information technology, so as to enhance driving safety, reduce driving time and guide driving routes. At the same time, managers improve their management efficiency by collecting real-time information of vehicles, drivers and roads, so as to make full use of traffic resources.

As a new automatic identification technology, RFID is very suitable for use in intelligent transportation and parking management due to its advantages of remote identification, storage and carrying of more information, fast reading speed, and wide application range. At present, RFID has gradually been successfully promoted and applied in the transportation field, and has achieved good social and economic benefits. Its application prospects are unanimously optimistic for the industry. In the field of intelligent transportation, RFID is mainly used in the following aspects:

(1) Electronic toll collection (ETC)

Electronic Toll Collection (ETC) is an electronic automatic toll collection system for highways, bridges and tunnels. It uses RFID technology to automatically complete the whole process of charging processing without the driver stopping and other toll collectors taking any action through the dedicated short-range communication between roadside antennas and on-board electronic tags. Non stop toll collection involves the recovery of traffic infrastructure investment, and is an effective means to alleviate traffic congestion at toll stations. In addition, the use of toll cards is large. Therefore, all countries give priority to the development of the application system of non stop toll collection system, and actively promote it. At present, its application in Europe and the United States is relatively mature and widespread, and China has also put it into use on expressways in Guangdong, Sichuan and other places. The application of the non-stop toll collection system can improve the traffic efficiency and prevent the occurrence of the traffic "bottleneck" at the toll station. At the same time, the RFID technology can realize the unattended charging, effectively curb the evasion of tolls, toll collectors' dereliction of duty, cheating on their own behalf and other behaviors, while reducing the management cost of the toll station and recovering the infrastructure investment more quickly.

(2) Electronic License Plate System (EVI) of Customs Terminal:

A large number of goods are loaded, unloaded, transported and cleared at ports, wharves and customs, and a considerable part of them are transported by vehicles. Therefore, there are many vehicles coming and going between port terminals and customs, and they may belong to different units in different industries such as customs, shipping companies, shipping agents, freight forwarders, port administrations, container terminals, etc. If unified measures are not taken, it is difficult to dispatch and manage, which brings great difficulties to customs clearance and the flow of goods. The electronic license plate management system based on RFID technology can effectively solve this problem.

By uniformly managing and registering vehicles, issuing on-board electronic labels, and placing RFID reading equipment at key access monitoring points, the system can enable the monitoring vehicles with electronic license plates to be identified accurately and timely by the identification system when passing through the monitoring channel, so as to meet the requirements of vehicle data collection. At the same time, wireless communication and other information technologies are used to submit the collected vehicle information to the management system to complete the vehicle identity confirmation, query, statistics, scheduling and other functions. The application of the electronic license plate system of the customs terminal can effectively improve the traffic capacity of customs vehicles, real-time statistics and monitoring of vehicle information, prevent false inspection and missing inspection, improve the efficiency of customs clearance, and prevent the organization of theft, crack down on smuggling and other acts.

(3) Urban traffic dispatching management system (TMS):

The vehicle dispatching management system is the core component of the intelligent transportation system. It uses advanced information communication technology to collect the dynamic and static information of road traffic, conduct real-time analysis, and arrange the driving route and travel time of vehicles according to the analysis results, so as to fully utilize the limited traffic resources, improve the use efficiency of vehicles, understand the vehicle operation, and strengthen the management of vehicles.

RFID technology can be used in traffic dispatching management system as an effective means of information collection. For example, the application of RFID to the bus yard management system can realize the automatic, accurate, remote and non-stop collection of information about the bus entering and exiting the station, so that the bus dispatching system can accurately grasp the real-time dynamic information about the bus entering and exiting the bus parking lot. The implementation of this system can effectively improve the management level of buses. The collected data can be studied and analyzed by computer, so as to grasp the rules of vehicle use, eliminate the loopholes in vehicle management, realize intelligent management of public vehicles, and improve the city image. At the same time, using RFID as a technical means has a high economy. Compared with the global positioning system (GPS) and other technologies, it has the characteristics of convenient installation, strong adaptability, low cost, and no need to modify vehicles. At the same time, some regions and cities have begun to apply RFID to the scheduling and management of special service vehicles such as garbage transport vehicles and dangerous goods transport vehicles. By placing electronic tags on the vehicle and reading equipment at the monitoring points of specific road sections, we can monitor whether the vehicle is driving according to the specified route and find the accident vehicle in time in case of leakage.

(4) Electronic registration management (EVR):

The registration of vehicles and the management of license plates have always been the focus and difficulty of traffic management departments. Black cars, false license plates and other problems have never been eliminated. But the new technology may become simple. One of the effective ways to solve this problem is to use RFID technology to realize the vehicle electronic registration management system. RFID electronic license plate is loaded after vehicle registration, because each label has a globally unique ID