Cost optimization and routing for satellite network constellations

Abstract

Low-earth orbit (LEO) satellite communications systems have been under rapid development in the past few years as it is predicted that they will become part of the Next Generation Internet (NGI), a global heterogeneous network that provides ubiquitous access to every part of the world. Nevertheless, very little research has been done on the cost aspect of a satellite network. In this thesis, uplink and downlink costs are ignored and a cost equation based solely on crosslinks is developed and studied closely together with a seamless constellation model. Using this cost equation, cost optimization is performed in LEO and GEO satellite systems to find the optimum constellation size with respect to the amount of uniform traffic present. Modifications of the constellations, such as the 3-crosslink-per-node mesh network, and the 1-inter-plane-crosslink mesh network, are introduced in an attempt to further reduce the cost of the system. Interaction of hotspot traffic with uniform traffic in a square mesh is also studied. We are able to find a lower bound and an upper bound of the minimum required crosslink capacity, given a stream of uniform traffic and multiple streams of hot spot traffic. We also find the properties of hot spot traffic in an infinite grid and extend the result to a fixed size grid. Finally, the notion of incorporating the satellite network into the global heterogeneous network is explored. The relationship between the satellite network and the terrestrial network is studied. In particular, the assignment of cost metrics to inter-satellite links, uplinks and downlinks, and terrestrial links is investigated. At the end a basic simulation of the traffic in a heterogeneous network is developed in MATLAB, which can be used to study the transient properties of the network.