# Distributed Coordination of Space-Ground Multiresources for Remote Sensing Missions
###### Abstract  
As data relay satellites (DRSs) play an increasingly important supporting role in remote sensing missions, efficient coordination across space-ground multiresources becomes a significant problem. Owing to the implementation problem of the centralized coordinate methods, this paper studies a distributed coordinate resource scheduling method which is realizable in the current space network structure. To be specific, we first formulate the multiple resource coordination problem into an MILP problem based on a modified time-expanded graph. Then, the problem is transferred and decomposed into subproblems for remote sensing satellite (RSS) systems and DRS systems to solve distributedly. Afterwards, we propose a distributed iterative scheme for the RSS systems and DRS systems based on alternating direction method of multipliers (ADMM), in which only the schedule information of the inter-satellite links are required to exchange between RSS systems and DRS systems. Simulation results are provided to validate the effectiveness of our distributed coordinated resource scheduling algorithm. remote sensing; space-ground resource coordination; resource scheduling +
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integrated observation mission scheduling method based on genetic annealing algorithm which realized the cooperation of the observation and data transmission phase [14]. Although the work in [12; 13; 14] improves the resource utilization of the whole networks through jointly scheduling the resources of RSSs and DRSs in a centralized manner, the implementation encounters immense obstacles in practice. Specially, these works assume all the resources in the space network are integrated and managed centrally. However, the resources belong to different RSS/DRS systems and are currently managed by their operation control centers. Many RSS and DRS systems are managed by different government departments or armies, each with their own interests [15], which cannot provide their local mission/resource information to or be managed by other departments. Therefore, it is urgent to develop distributed coordinate resource scheduling strategies which do not need global information and uniform management. The technical challenges of designing efficient distributed coordinated resource scheduling mechanism are threefold: (1) How to design a distributed coordinated framework among the RSS and DRS systems based on the current network architecture? (2) How to reduce the amount of local mission/resource information required to be exchanged among the satellite systems? (3) How to realize the coordination not only between RSS system and DRS system but also among RSS systems? To address the above technical challenges, this paper studies a distributed resource scheduling method to realize the resource coordination between RSS systems and DRS systems. The contributions are outlined as follows:  
* By modifying the time-expanded graph, we formulate a joint optimization framework of multiple resource scheduling of the RSS systems and DRS systems and decompose it in terms of each satellite system. * Based on the alternating direction method of multipliers (ADMM), a distributed coordinated space-ground multiresource scheduling method is developed for remote sensing missions. Compared with the centralized counterparts, it not only does not require the introduction of network entities into the current network but also avoids any information exchange outside the schedule information of the intersatellite link between RSSs and DRSs. Therefore, the proposed method is much more practical than the centralized methods. * Simulation results shows that the performance of the proposed method is very close to that of the centralized method and is much better than the noncoordination method. The rest of the paper is organized as follows. Section 2 presents the network model as well as the optimization formulation of the distributed coordinated multiresource scheduling problem of the integrated network.