International Core Journal of Engineering 2020-26 | Page 114

2019 International Conference on Artificial Intelligence and Advanced Manufacturing (AIAM) RFID Multi-channel Design Method Based on CDMA Ping Du Yanfen Shen Yuewei Zeng Building Information Department Guangdong Construction Polytechnic Guangzhou, China [email protected] Building Information Department Guangdong Construction Polytechnic Guangzhou, China [email protected] Building Information Department Guangdong Construction Polytechnic Guangzhou, China [email protected] tag by combining CDMA and time slot Aloha. Liu Xinqin et al, from Taiwan University adopt Huffman sequence as the spread spectrum [2]. It can be seen that domestic and overseas scholars have conducted different researches and explorations on code division RFID. Abstract—This paper analyzes the application of Code Division Multiple Access (CDMA) to ultra-high frequency (UHF) RFID technology and the coding sequence of shift M- sequence as CDMA. M-sequence is characterized by better positive correlation and the sufficient number of orthogonal codes, so the application of it in UHF RFID is the development of RFID technology. This paper focuses on characteristics, generation and multi-channel realization of M-sequence. The integration of CDMA and RFID technology can realize the simultaneous response of multiple tags and become a new anti- collision method to improve the reading rate. This technology brings new research direction of RFID to new area with multiple channels, high spectral efficiency and high signal to noise ratio. Keywords—CDMA, correlated operation RFID, M-sequence, This paper breaks through the bottleneck of air interface access capability of UHF RFID, adopts the concept of multi- channel access, applies CDMA cellular communication network to UHF RFID air interface, realizes the integration of orthogonal code division access and spread spectrum based on communication, establishes code division RFID system and realizes the simultaneous access of multi-channel tag information [3]. In this way, the reading rate can be improved, the pressure of collision can be alleviated and the spectral efficiency and anti-jamming capability can be enhanced [4]. multi-channel, I. I NTRODUCTION II. CDMA S PREAD S PECTRUM M ETHOD BASED ON M- At present, 5G era comes with higher speed and wide development prospect. It is estimated that the connection to 5G in China will be more than 400 million in 2025. Internet of things (IoT) relates any object to network by information sensing equipment, so as to realize the intellectualized identification, location, tracking and surveillance. Constrained by the coverage of wireless network and communication speed, IoT fails to truly develop. With the advent of 5G network, supported by its great communication speed, the development of IoT technology will embrace a new breakthrough in future several years. With RFID technology as the important and critical technology of IoT technology [1], and the development of 5G technology, people look forward to its performance and reading rate. However, RFID technology requires further optimization and innovation to promote the integration and development of 5G technology and IoT. SEQUENCE The spread spectrum technology is to make use of spread spectrum code sequence caused by spread spectrum code generator to module digital signal, so as to widen the spectrum of signal. The signal widened is modulated to radio frequency to be sent out. The received broadband radio frequency signal can realize related dispreading by locally- caused spread spectrum code sequence that is same to generating terminal, and recover to raw information output. The spread spectrum technology can bring multiple benefits to communication system [5]. Firstly, strong anti-jamming capability. The wider the widening channel of spread spectrum is, the higher the processing gain received is, the larger the jamming margin, and the stronger the anti-jamming capability. Secondly, better confidentiality. Digital information modulated is similar to random noise. When the receiving terminal performs dispreading, only simultaneous spread spectrum code is adopted to correctly recover information sent. In this way, information is confidential. The air interface of UHF RFID currently adopts single- channel access, and collision decision is one of cores of communication protocol. The anti-collision algorithm has been improved for several times, however, people fail to achieve fundamental breakthrough, especially the collision between multiple readers in dense configuration. American Caro Mutti and Caristian Floerkeneire establish the tag application scheme with the combination of CDMA and Aloha through Gold sequence and Kasami code. Gustaw Mazurek, in Active RFID System With Spread-Spectrum Transmission, conducts a research on code division channel by adopting 16 127-bit Gold sequence. In 2011, German Andress Loefler et al. realize the simulation of semi-passive 978-1-7281-4691-1/19/$31.00 ©2019 IEEE DOI 10.1109/AIAM48774.2019.00025 Thirdly, the anti-fading and anti-multipath interference capability. The spread spectrum system owns potential anti- frequency-selective-fading capability, and can effectively overcome multipath interference. Fourthly, CDMA easily realized. The pseudo-random sequence spread spectrum is adopted in spread spectrum communication system so as to realize the CDMA communication. 92