Optimization of connection oriented, mobile, hybrid network systems

In this paper, we consider the extension of a cellular system by means of s atellite channels. Specifically, we consider an area covered by a number of cells, that is also covered by a number of spot beams. We consider connect ion-oriented service, and call durations are assumed to be exponentially di stributed. Also, users are mobile and, as such, they may cross cell and/or spot-beam boundaries, thus necessitating handoffs, We incorporate the possi bility of call dropping due to unsuccessful hand-off attempts, in addition to satellite propagation delays along with the probability of new call bloc king, and formulate a specific multifaceted cost function that must be ulti mately minimized. The minimization is to be carried out by choosing: 1) the optimal partitioning of channels between the cellular and the satellite sy stems, and ii) the call admission and assignment policy, subject to the con straints of a demand vector that consists of an exogenous (new-call) genera tion process and an internal (handoff-based) process that results from the mobility model, Two subproblems of this complex optimization problem are so lved by means of numerical techniques and by means of so-called standard cl ock simulation techniques. In this solution method, we employ the ordinal o ptimization approach which focuses on preserving the performance rank, rath er than the performance prediction of the different control policies. We fi nd that the "double" coverage, through both cellular and satellite resource s, results in substantial improvement over pure terrestrial or pure satelli te systems for parameter values that correspond to practical environments.