Research On Multi-tag Localization And Concurrent Information Transmission For Backscatter System

In many Io T applications,the location and individual information of the target(such as ID,temperature,etc.)are of great practical value.For example,in a large logistics system,if you can accurately obtain the location of the target,identity ID information,and even temperature and humidity information(fresh and other items),etc.,you can achieve efficient and low-cost intelligent management.To this end,this dissertation implements a backscatter multi-tag system based on Wi-Fi signals.The system can realize multi-target localization,and can also realize simple and low-cost concurrent information transmission on the same frequency without control protocol.Research content and main contributions of this dissertation include:1.Based on the idea of SAGE algorithm,this dissertation implements a multipath signal separation algorithm.The algorithm does not need to modify the signal bandwidth or add additional equipment,and the high-precision separation of multi-path mixed signals can be achieved only by jointly estimating the multi-dimensional channel parameters(such as signal angle of arrival(AOA),angle of departure(AOD),time delay(TOF))with high precision.2.To solve the problem that the absolute TOF is not accurate enough,resulting in the location calculated by the location algorithm cannot be guaranteed to be unique,the system uses TOF difference(relative time)to eliminate the effect of absolute TOF inaccuracy,so as to ensure that the location calculated by the location algorithm is unique,thereby eliminating the ambiguity of the location.And on this basis,this dissertation proposes a high-precision location scheme based on AOA,AOD,and signal propagation path length.3.For the problem of concurrent conflicts that multi-tag system may encounter in data transmission,this dissertation proposes a simple and low-cost concurrent transmission scheme on the same frequency without designing the MAC layer control protocol.This scheme establishes the correlation map of the data to be transmitted(such as ID,temperature,humidity,etc.)by establishing the time-dependent statistical characteristics of the channel parameters(AOA,AOD,TOF)of the signals on different propagation paths.At the same time,this dissertation uses a voting algorithm to further improve the robustness of the scheme.