Abstract
Introducing InterSatellite Links (ISLs) is a major trend in new-generation Global Navigation Satellite Systems (GNSSs). Data transmission scheduling is a crucial problem in the study of ISL management. The existing research on intersatellite data transmission has not considered the capacities of ISL bandwidth. Thus, the current study is the first to describe the intersatellite data transmission scheduling problem with capacity restrictions in GNSSs. A model conversion strategy is designed to model the aforementioned problem as a length-bounded single-path multicommodity flow problem. An integer programming model is constructed to minimize the maximal sum of flows on each intersatellite edge; this minimization is equivalent to minimizing the maximal occupied ISL bandwidth. An iterated tree search algorithm is proposed to resolve the problem, and two ranking rules are designed to guide the search. Experiments based on the BeiDou satellite constellation are designed, and results demonstrate the effectiveness of the proposed model and algorithm.
Highlights
As a key technology of Global Navigation Satellite Systems (GNSSs), InterSatellite Links (ISLs) from the main GNSSs of the world, including GPS, GLONASS, Galileo, and BeiDou, have received significant attention[1]
The transmission line includes three types: the transmission line between a domestic node and a sink node is converted into a ground satellite edge; that between the same satellite at different statuses corresponds to an intrasatellite edge; the transmission line between two linked satellites at one slot is an intersatellite edge that is equivalent to the ISL such that the flow amount of the intersatellite edge reflects the consumption of ISL bandwidth
upper bound (UB) is initialized to a small value and increased gradually until every commodity has an available transmission path so as to find a feasible solution and reduce the ISL bandwidth consumption as much as possible. 4.1.2 Path length ascending rule The data transmission time delay is the main constraint of this problem that limits the maximal length of transmission paths
Summary
As a result of the dynamic visibility between satellites and the pointing flexibility of narrow-beam antennas, time-evolving navigation intersatellite networks can be modeled as a Finite-State Automaton (FSA)[15]. Each FSA state contains several equal-length time intervals, which are defined as superframes. All superframes in a state have the same contact plan. Each superframe consists of several equal-length time slots, and an ISL between two satellites is established at each slot. The ISL is a bidirectional link, and the ranging and communication between linked satellites can be implemented at each slot simultaneously. Each satellite has only one onboard Ka-band antenna so that each satellite holds a maximum of one link at a slot. ISLs switch between adjacent slots according to a predesigned contact plan.
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