Satellite Scheduling for Educational Ground Station Networks

Paper number

IAC-08.B4.3.6

Author

Mr. Marco Schmidt, Wuerzburg University, Germany

Coauthor

Prof. Klaus Schilling, Wuerzburg University, Germany

Year

2008

Abstract

The small satellite community initiated recently the development of many ground stations,  built for communication in the  corresponding pico and nano satellite projects.  Ongoing activities like GENSO (ESA) or GSN (UNISEC) show, that there is a strong demand in ground station networks at university level. These networks promise to extend communication time with the satellites and to increase utilization of the ground stations by sharing resources. One unsolved problem in this field is an optimal scheduling strategy for ground station networks.

In computational complexity theory the satellite scheduling problem is considered as NP-complete, meaning that no efficient algorithm for finding an optimal solution is known, but a number of heuristics and algorithms exist to search for appropriate scheduling solutions. National space agencies work on the problem of automatic satellite scheduling for a long time, nevertheless they still use very often handmade schedules due to their high requirements. Satellite missions or space stations need continuous operation and therefore a conflict free, long term schedule is required. The University of Wuerzburg developed a new approach for satellite scheduling, as the needs of educational ground station networks are different. Here the main objective is to increase the number of contact windows and to improve the utilization of the ground stations at the distributed institutions. Satellites of universities do not need permanent communication, nevertheless a high utilization of available resources (ground stations) should be achieved.  Another important issue is the time frame of the required schedules. The national agencies have to plan in a time scale of several month, a reschedule for fast interaction is then a complex and costly task. Educational ground station networks on the other hand need only schedules for several weeks, resulting in a more flexible rescheduling.
 
The paper presents a new approach for satellite scheduling developed at the University of Wuerzburg. In contrast to standard scheduling algorithms the approach addresses the special peculiarities of educational  ground station networks (e.g. many small satellites in LEO, more flexible communication requests) and therefore better satisfies the needs of those networks.  Advantages of this new approach are the “online” capability of creating schedules in a fast and efficient manner. The paper explains the advantages and limitations of the new approach, furthermore an implementation of the system will be presented to demonstrate a practical solution for educational ground station networks. 

Abstract document

IAC-08.B4.3.6.pdf

Manuscript document

IAC-08.B4.3.6.pdf (🔒 authorized access only).

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