Dynamic topology control in optical satellite networks based on algebraic connectivity

Abstract

Optical communication satellite network (OCSN) has been considered as a superior solution to broadband applications of space-based information, since it has many advantages such as less power and higher data rate. Topology framework is the foundation and premise of OCSN. However, frail links, limited number of optical transceivers and time-varying network topology deteriorate topology control of OCSN. Usually, topology control is mainly conducted in processes of network bootstrapping and reconfiguring. In this paper, we investigate the problem of topology control about constructing robust spanning trees in above two processes. The model of OCSN based on space-time graph is built and link availability is proposed to represent the capability of choosing strong links. In addition, the algebraic connectivity is introduced to measure robustness of spanning trees and then the problem is formulated as a 0-1 multi-objective mixed-integer nonlinear programming (MOMINP) which has been proven to be NP-hard. For fast constructing a spanning tree with large algebraic connectivity and average edge weight in OCSN, we develop the subtree merging and maximizing algebraic connectivity (SMMAC) algorithm that is effectively appropriate for distributed network bootstrapping and reconfiguring, and also discuss the properties of SMMAC containing outcome existence, computational complexity and approximation analysis in this paper. The algorithm is based on a primal decomposition method to solve MOMINP, which can efficiently reduce the complexity. Some simulations are conducted in two typical distributed scenarios. Results demonstrate that, compared with other alternative algorithms, our algorithm can significantly improve algebraic connectivity of OCSN and meanwhile guarantee relatively high average edge weight for the topology of OCSNs.