Research And Verification Of Key Technologies Of Time Synchronization In Wireless Trunking Ad-Hoc Network

Wireless trunking communication Ad-hoc network is gradually responsible for covering the last kilometer of wireless communication in special application scenarios,like as military combat, management of tourism scenic region, security of major events and airport command. Synchronous and stable network time is the base for orderly work in Wireless trunking communication Ad-hoc network. Existing network time synchronization protocols have covered the hierarchical network and flat network, center and non-center network. Some network time synchronization algorithms have studied the aspects of synchronization precision, convergence speed, complexity and stability. However, the research of network time synchronization protocols, which are apply to network which both have center network and non-center network, are not enough.In this paper, the key technologies of time synchronization in wireless self-organized trunking communication networks, which both have center networks and non-center networks, are studied and validated. Firstly, from the overview of wireless trunking communication Ad-hoc network and network layer to the research in network time synchronization technology, the research status at home and abroad are analyzed. Then, combining the actual project, the functional requirements and performance constraints are analyzed in detail. Next, a viable network time synchronization protocol and scheme are implementated and verificated on the FPGA chip. Finally, the real test of network time synchronization in Wireless trunking communication Ad-hoc network are analyzed.(1) The typical network time synchronization algorithms are analyzed. In this paper, during analyzing the research status, the work principle and the process flow of the three typical time synchronization algorithms are analyzed, in order to make a reference and contrast for the following time synchronization protocol.(2) The protocol and implementation of network time synchronization are designed. The network structure includes both a network in the center of a vehicle base station and a non-center network with mobile subscribers only. Periodic one-way delay measurement time synchronization protocol is used in this paper.The communication modes of mobile subscriber monitoring, direct communications and vehicle base station communication,as well as a detailed flow of time synchronization are also designed. In this paper, the communication time slot is obtained by dividing the local network time, and the mode operation is used to realize the cycle counting, and the transmission delay is compensated by the fixed value.(3) The implementation and verification of network time synchronization are completed. The paper focuses on design reason, working principle and process flow of modules, discussing the implementation of design from the system structure of the communication device to interface and submodules. Finally, the experimental results of the implementation are analyzed.The timing accuracy is designed for 125 ns, synchronization error is limited within the 50 us, time slot period is set to 2.1875 ms, field measurements show that the average length of time slot is 2.1875 ms with a variance of 0.992 ns, and the time synchronization error is less than 35 μs, it takes less than 280.07 ms to finish the convergence of time synchronization. This paper can be instructive for time synchronization of a small ad hoc wireless cluster private network which has center and non-center network mixing existing.