| Using millimeter wave communication technology to connect long-stay platforms in the near space,such as long-endurance drones,airships,floating air balloons,etc.,to form an important air-ground link forwarding and ground service in an integrated air-space network Access and air communication service networks are increasingly valued by people.In view of the widespread use of Ethernet in terrestrial networks,the link layer of the near space millimeter wave communication network is also implemented using Ethernet technology.Under this premise,in this paper,without satellite navigation assistance,we rely on our own communication links to achieve high-precision synchronization to achieve highperformance and low-latency communication service forwarding,and support the near space of collaborative communication and control tasks based on floating platforms Millimeter wave packet network synchronization technology.In order to achieve this goal,we refer to the clock synchronization technology in Time-Sensitive Networks(TSN),study the implementation of high-precision synchronization protocols and important mechanisms in TSN,analyze the performance and requirements of the node's local phase-locked loop jitter index through experimental research,and analyze the clock synchronization characteristics of the near space millimeter-wave network platform and propose a synchronization protocol and hardware structure that support millimeter-wave near-space network synchronization.The main research contents of this article are as follows:First,the Ethernet-based time-sensitive network synchronization protocol is researched in depth,and the links that affect the synchronization accuracy of the protocol synchronization method,time information acquisition,transmission,and processing are analyzed.Through experimental research,a time-sensitive network protocol test research system was built,and the protocol synchronization performance and phase-locked loop index in the experimental system were tested and analyzed.Based on this,a basic synchronization scheme suitable for millimeter wave platforms in near space is proposed.Secondly,for the key aspects affecting synchronization accuracy,for each node's own clock phase-locked loop,combined with experimental and theoretical models,this paper analyzes the main sources of phase-locked loop phase noise,and summarizes common noise suppression methods.Based on the laboratory prototype verification system,a number of tests were performed for the characteristics of phase-locked loop phase noise,and improvements were made to the oscillator and loop filter bandwidth,and the correctness of the theoretical analysis was basically verified.Finally,the paper analyze and understand the behavior level dynamic change of the communication link of the near space millimeter wave network.Combining the foregoing results,a node clock synchronization scheme suitable for the near space millimeter wave platform is proposed.Based on the integration of Ethernet-based communication and synchronization protocols,this solution can improve the time synchronization stability and reliability of floating platform millimeter-wave links.This design fully considers the accumulation of multi-hop errors caused by platform dynamics,especially link errors caused by platform attitude disturbances,which can effectively prevent the transmission and diffusion of external clock synchronization transient errors.The simulation analysis of the synchronization scheme by network simulation software verifies the superiority of the proposed method.The work done in this paper not only lays a solid foundation for the realization of highprecision synchronization of near space floating platforms,but also provides the necessary conditions for supporting deterministic services on quasi-dynamic networks,which is worth further research through prototype systems. |
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