Large-scale Backscatter Tags Multiple Access Networking And Prototype Platform Construction

The Internet of Things has become a hot topic in recent years.However,with the rapid development of the Internet of Things applications,the problem of node energy acquisition has become an important bottleneck restricting its development.As a result,backscatter transmission networks have received widespread attention due to their ultra-low power consumption characteristics.The main advantage of a backscatter network is that the backscatter sensing nodes obtain energy from the environment without relying on external equipment to provide energy.It can be said that the birth of the backscatter communication network successfully solved the problem of node energy acquisition encountered by the Internet of Things.On the other hand,the explosive growth of IoT devices has also brought new de-mands and challenges to its development.Most of the existing work focuses on the application scenarios of a single node.Multiple or even a large number of nodes still cannot communicate and transmit data at the same time,which will greatly limit the feasibility of large-scale deployment of Internet of Things devices in the future.In view of these problems,this paper proposes a passive backscatter communica-tion system that can support multiple passive tags to transmit data efficiently and reliably at the same time.This system uses the code division multiple access method.Compared with the frequency division multiple access method,this method can achieve lower over-head in both the communication and computing domains.Each tag node can send and receive data packets according to a fault-tolerant coding scheme in a distributed manner.In addition,it can tolerate imperfect synchronization of data between tags.A large num-ber of experiments show that this system can support up to 10 tags with a total bit rate of 8Mbps,and the longest communication distance is 10 meters.Compared with the single-tag scheme,even in challenging indoor scenarios with multipath and other signal interference,the system throughput can be increased by more than 10 times.Thus,this verifies the feasibility of using code division multiple access to achieve large-scale pas-sive tags and high-speed transmission of data simultaneously.The main work of this paper is as follows:1.Propose a backscatter communication system that uses code division multiple access to achieve multiple tags to simultaneously transmit data at high speed,and use related equipment to build a system prototype platform.2.Study the factors that affect the energy intensity of the reflected signal of the backscatter tag and when multiple tags are transmitted at the same time,there is per-formance difference between each tag,and analyze the impact of the energy difference between the tags.3.An effective energy control method is proposed to effectively select different antenna impedances on the tags,and a tag node deployment scheme is provided to fur-ther optimize the performance of the entire system when the energy control method is still not satisfactory.