Jointly Optimal Routing and Resource Allocation in Hybrid Satellite/Terrestrial Networks

Recent research has introduced the concept of Network Utility Maximization (NUM). In the formulation of a NUM problem, each layer of a communication network corresponds to a decomposed subproblem of a global optimization problem, and the interfaces among layers are represented as functions of the optimization variables coordinating the subproblems. These sets of variables are coupled through precise restrictions. For example, efficient routing at network layer depends on the link capacities which, in turn, are determined by the allocation of resources (such as transmit powers and bandwidths) to the links at radio control layer. We exploit this separable structure by formulating the problem as a convex optimization problem which can be solved by means of the Lagrange dual decomposition method. This kind of optimization promises interesting developments in satellite/terrestrial systems, because of the inherently challenging feature of such scenarios, i.e. strict constraints in terms of power and bandwidth.