Research on Physical Layer of Passive IoT Communication Protocol Based on Cellular Fusion

As transportation, logistics and other industries put forward the demand for low-cost item tracking, it is urgent to use the advantages of cellular networks to achieve seamless coverage of the connection of things, and realize the universal internet of everything in a true sense. In view of the shortcomings of traditional radio frequency identification (RFID) technology, such as limited communication distance, large interference, inability to continuous networking, high deployment and human operation and maintenance costs, and no support for positioning, this paper proposes a cellular fusion passive air interface protocol stack physical layer communication scheme. Based on the 18000-6C protocol, 256 quadrature amplitude modulation (QAM) is introduced in the downlink and an improved Pulse interval encoding (PIE) encoding is proposed. Tail biting convolutional codes (TBCC) and Polar code are used in the uplink to improve communication distance and optimize inventory efficiency. The signal level and error rate curve of the communication link are simulated. The simulation results show that both the base station and the label can send and receive data correctly. In the downlink, the bit error rate (BER) decreases with the increase of modulation depth. In the uplink, binary phase shift keying (BPSK) modulation has better error performance than amplitude shift keying (ASK) modulation, and Polar code has better error performance than TBCC.