With the development of Internet of Things technology, RFID technology has been widely used in all walks of life, such as tourism star hotels and scenic spots. Guests can access the scenic spot by holding an RFID tag card. The RFID system has a long-distance automatic identification function. The access door will automatically open after identifying the information, otherwise it will automatically alarm and close the access control. RFID readers and tags produced by different manufacturers must ensure the consistency and interoperability of product communication protocols. Therefore, it is necessary to test the tag protocol. However, if the actual measurement method is used, it will not only be time-consuming and laborious, but also waste property. Based on this , the paper proposes a co-simulation analysis research scheme of RFID protocol consistency. In this scheme, the RFID tester completes the baseband signal processing based on the RF transceiver and FPGA, and simulates and demodulates the commands sent and received by the RFID tag in real time. According to the qualified simulation results, manufacturers can better develop new RFID products based on tourism, provide guarantee for the development of smart tourism, and provide better services for tourists in scenic spots.

1 Introduction to RFID system

RFID technology originated in the 1940s, when radar retrofits were used to distinguish between enemy and friendly aircraft.In the 21st century, RFID technology has been used in all walks of life, such as tourism, manufacturing, etc. Its structure mainly includes readers, Electronic tags and computer networking systems, among which electronic tags contain chips, which not only store a large amount of information. [1-2], the information processing speed is fast, the pollution of the external environment can also be avoided, and the safety performance is good. The reader can also identify tags from a long distance, which is convenient and fast.

2 The working principle of RFID system

The RFID system uses radio frequency identification technology to complete the reading of the information in the electronic tag.

(1) The software of the reader sends read and write commands to the reader, and transmits radio frequency signals to the electronic tag through the antenna to establish specific communication;

(2) The electronic tag antenna receives the signal, and the signal enters the control part of the electronic tag through the RF front-end circuit, and the control part performs various logical processing on the data stream[3-5] ;

(3) The electronic tag transmits the internal signal to the reader through the antenna, and the reader transmits the signal to the upper layer of the system to read the identification information, and the upper layer transmits the information over a long distance.

3 RFID Protocol Consistency Simulation

RFID uses the radio frequency signal transmitted by the reader to the tag, reflects the echo signal through the tag, and receives and obtains the information stored in the tag. Among them, the information modulation is completed by the tag chip, so whether the RFID communication protocols of different merchants are consistent is related to whether the information reception is smooth.

3.1 The working principle of RFID protocol consistency

Investigate and test the tag’s response to RF signals in the full frequency range (860 to 960 MHz) and whether the response signal occupies a limited bandwidth.Protocol conformance simulation test includes tag processing time test, tag memory data structure test, tag instruction test, tag state machine conversion and card reader protocol processing time test. Protocol Consistency and Efficiency [6-8]. At the same time, set the distance between the tag and the test antenna to be 3m, the transmission power of the test system to be PHS, the reflected power of the recorded tag to be PI, and the calculation formula of the tag scattering cross section RCS is:

In the formula: d represents the distance of the antenna tag; Gr represents the antenna test gain; λ represents the carrier wavelength; K represents the correction factor.

3.2 Test method for protocol conformance

Enter the simulation software environment, use virtual instruments, general-purpose vector signal generators to generate excitation signals, vector signal analysis equipment to capture and collect signals, rely on SSE high performance to carry out assembly technology for testing, and complete radio frequency technologies such as RFID and low-frequency technology on the CPU of X86 architecture. Index Simulation Analysis and Measurement Solution Analysis of Power Wireless Mobile Networks [9-10]. Use RFID simulator and wireless channel simulator to simulate and analyze RFID’s protocol parameters, non-protocol parameters and command control interfaces, analyze the physical layer and protocol layer, realize the generation and communication of protocol signals, and also measure the activation of tags. The minimum transmit power EIRP (dBm) (sensitivity) of , and then according to the distance d of the transmit antenna, use the Friis formula to calculate the maximum forward activation distance of the tag:

In the formula: EIRP represents the minimum transmit power when the tag is activated; d represents the distance of the transmit antenna.

The system has a dual-mode function to complete card reader emulation and tag emulation. The test flow is shown in Figure 1.

3.3 Analysis of Simulation Results of Protocol Consistency

The simulation test and analysis of the RFID protocol consistency of the access control system of a 5A-level scenic spot are carried out. The signal works in the UHF frequency band, the protocol test is based on ISO18000-6C, demodulates the command of the tag or reader, and simulates the returned bit stream. The RFID measurement and simulation system is combined to complete the conformance test of the protocol. Real-time baseband processing using an FPGA to complete physical layer measurements while simulating tag reading. The enlarged view of the label protocol consistency area is shown in Figure 2. According to the return waveform of the tag and the analysis of the tag command, it can be analyzed that the protocol consistency between the reader and the tag has reached the standard and meets the requirements for use.

4 Conclusion

Using this RFID product protocol consistency simulation test solution, the RFID protocol consistency of different manufacturers can be tested. This solution uses virtual instruments, generates excitation signals through vector signal generators, captures and collects signals by vector signal analysis equipment, relies on SSE to carry out index test simulation, and completes index simulation analysis and measurement analysis of RFID and other radio frequency technologies and low-power wireless mobile networks . It is convenient for the tourism industry to choose different RFID products and realize interoperability and interoperability, laying a foundation for providing high-quality services for tourists, providing support and guarantee for manufacturers to develop RFID products, and bringing certain help to the economic development of the Internet of Things.