Improvement Of LWIP Protocol And Its Application In Group Satellite Cooperative Imaging

In recent years,small satellites have been playing more and more important roles in the field of spaceflight due to their advantages of low cost,light weight and easy launch,which have become the focus of satellite research both at home and abroad.In order to improve the application efficiency,small satellites are more and more inclined to use the way of group stars,in recent year,the single satellite can work independently or cooperatively through satellite networks in the more advanced small group satellites abroad,however group star research has only just begun,no related application reports at home.One of the most common applications is in the cooperative imaging of optical remote sensing small satellites,especially wide-range imaging and gaze imaging,which can solve the problems of low orbit optical remote sensing small satellite image width and short gaze imaging time.The real-time nature of the group star network has very big request,need to solve the problem of network agreement.On the basis of all aspects,this paper proposes a group star network scheme with improved LWIP protocol,and carries out simulation experiments on cooperative imaging.In this paper,we first describe the great advantage of small satellites and the problems to be solved.By using the common satellite network protocol,we proposean improved LWIP protocol to be applied to the star network.Aiming at the special requirements of inter-satellite communication,an improved method of network protocol is proposed,and the lightweight IP protocol LWIP is improved to obtain the network protocol applicable to inter-satellite communication.In order to verify the feasibility of the improved network protocol and the small satellite cooperative imaging scheme,this paper builds a small satellite communication platform on which the FREERTOS operating system,FATFS file system and the improved LWIP network protocol are transplanted.At last,multi-task file operations,multi-platform communication,multi-platform collaborative imaging and other experiments were performed on the platform.Experiments show that the improved network protocol designed in this paper can further reduce the network delay,and it is feasible to apply it to the cooperative satellite imaging.