| A single communication function cannot well meet the requirements of highly dynamic wireless network networking,because burst communication and routing rely on high-precision time synchronization and spatial precision positioning.If there is a lack of external time and location services,the nodes in the network must have synchronization and relative positioning capabilities themselves.However,if corresponding equipment is specially equipped to achieve these functions,it will not only increase the load weight but also be more expensive.Therefore,this thesis mainly studies communication synchronization and positioning integration technology in a highly dynamic environment,which can effectively solve this problem.Based on the communication signals of device nodes,this thesis studies the function of high-precision time synchronization and relative positioning in high-dynamic scenarios.The main research contents are as follows:(1)Research on time synchronization and positioning between nodes based on a single interaction cycle state accumulation of ultra-wideband(UWB)signals.First,a system model is established to get the send and receive timestamps by communicating with UWB signals.Store the timestamp information in the data domain of the UWB signal so that nodes can share the information after communication.Based on the traditional two-way ranging(TWR)method,the time-of-flight(ToF)of the signal is simply coarsely estimated,and then the state and relationship of each frame in an interactive cycle are further analyzed.Next,based on this,the ToF is modified to compensate for the estimation deviation caused by the time asynchronization and relative speed,and the time offset between nodes is estimated to achieve synchronization between nodes.After that,Kalman filtering is used to remove measurement noise and reduce errors,thereby improving the accuracy of calculating the relative distance between nodes.The numerical simulation results show that the proposed method can achieve a positioning accuracy of 10 cm and a time synchronization accuracy of 1 ns in a dynamic environment.In addition,the proposed method satisfies the Cramer-Rao Lower Bound(CRLB)of ranging performance,and the accuracy of time synchronization is better than the Reference Broadcast Synchronization(RBS)algorithm.(2)Research on time synchronization and positioning between nodes based on two interaction cycles state accumulation of orthogonal time frequency space(OTFS)pilot.This method first estimates the time delay and Doppler shift of the signal propagation process by matching filtering with OTFS pilots,then further obtains the corresponding timestamps and exchanges time information between communication nodes.Based on the time synchronization and positioning of the UWB signal,the time synchronization and positioning under the OTFS signal are further realized.The ToF iterative compensation and correction process in each communication is simplified by extending the state and relationship of one interaction cycle to two interaction cycles.The final simulation results show that the method can also estimate the signal propagation delay and Doppler frequency shift well at a low signal-to-noise ratio(SNR).The numerical simulation results show that the method also achieves centimeter-level positioning accuracy and nanosecond-level time synchronization accuracy. |
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