Optimization of connection-oriented, mobile, hybrid network systems

摘要

We consider the extension of a cellular system by means ofnsatellite channels. Specifically, we consider an area covered by annumber of cells, that is also covered by a number of spot beams. Wenconsider connection-oriented service, and call durations are assumed tonbe exponentially distributed. Also, users are mobile and, as such, theynmay cross cell and/or spot-beam boundaries, thus necessitating handoffs.nWe incorporate the possibility of call dropping due to unsuccessfulnhandoff attempts, in addition to satellite propagation delays along withnthe probability of new call blocking, and formulate a specificnmultifaceted cost function that must be ultimately minimized. Thenminimization is to be carried out by choosing: (1) the optimalnpartitioning of channels between the cellular and the satellite systems,nand (ii) the call admission and assignment policy, subject to thenconstraints of a demand vector that consists of an exogenous (new-call)ngeneration process and an internal (handoff-based) process that resultsnfrom the mobility model. Two subproblems of this complex optimizationnproblem are solved by means of numerical techniques and by means ofnso-called standard clock simulation techniques. In this solution method,nwe employ the ordinal optimization approach which focuses on preservingnthe performance rank, rather than the performance prediction of thendifferent control policies. We find that the “double”ncoverage, through both cellular and satellite resources, results innsubstantial improvement over pure terrestrial or pure satellite systemsnfor parameter values that correspond to practical environments