# Satellite Network Task Deployment Method Based on SDN and ICN
## 3 System Model and Problem Formulation  
### Scene Overview  
With the operation of the 5G mobile communication network, the use of IoT devices based on mobile communication systems will also grow rapidly [19]. The base stations of the ground mobile network are often deployed in densely populated areas. In areas without ground network coverage, there are also access requirements for IoT equipment, such as forest, ocean, air, and other scenes, so a satellite communication system is used to collect IoT data in this area. Compared with a geostationary orbit (GEO) satellite, a low-orbit (LEO) satellite can reduce the propagation delay and transmission loss. This is helpful for saving the energy consumption of IoT equipment in remote areas. In addition, the global seamless coverage can be achieved through the constellation composed of multiple LEO satellites. This improves the coverage of the satellite network and alleviates the difficulty of GEO satellite orbit position and frequency coordination. To enable high-efficiency control of the low-orbit satellites, a layered satellite networking scheme is considered. GEO satellites are widely used in the control layer of hierarchical satellite communication systems because of their wide area coverage and high load capacity. In this approach, the GEO satellite is mainly responsible for the topology monitoring and flow monitoring of the LEO constellation. Compared with transmitting all the original data to the ground station for processing, the onboard calculation can significantly reduce the communication volume of intersatellite links and reduce the processing delay of the tasks. Two kinds of application scenarios of satellite network are considered, including providing traffic services and computing services for users and the satellite Internet of things--wherein the ground IoT equipment uploads the data to the low-orbit satellite node and then transmits the processed data to the ground station after in-orbit integration. Figure 1 is a schematic diagram of the satellite network scenarios. The SDN controller is deployed to GEO Satellite and the network scenario includes user terminals, data monitoring devices, Internet of things devices, and other devices to access the LEO satellite network. The LEO satellite undertakes the tasks of data forwarding, content caching, and computing services of the access devices. It is assumed that each LEO satellite has only four communication links: the communication links with adjacent satellites in the same orbit and the communication links between satellites in different orbits. The local processing performance of the access devices cannot meet the computing requirements. Therefore, this needs to be transferred to the LEO satellite network for processing. The task processing flow based on SDN and ICN Technology is presented in Figure 2.  
Figure 1: The satellite network scenario. In the communication mode based on the ICN, the communication between end-to-end devices is based on two kinds of transmission packets: interest packets and data packets. Based on the global naming mechanism, the content has a globally unique name identifier. After receiving the packets, the nodes in the communication link cache them in the current node according to a certain strategy. The onboard cache greatly improves the response time when the content is requested again. In this paper, the idea of edge computing is introduced into the satellite network and the problem of computing offload in satellite networks is considered. As shown in Figure 2, step one is for the task initiator to distribute the task to the connected LEO satellite. Step two is to send mission requirements to the GEO satellite, namely the SDN controller, for the mission receiving satellite. The SDN controller collects the resources and link states of the LEO nodes. In step three, the SDN controller decomposes the task into smaller subtasks and performs the task deployment method proposed in this paper to find the optimal placement position of the subtasks.