doi:10.1016/j.comcom.2006.08.017
Copyright © 2006 Elsevier B.V. All rights reserved.
Designing cellular networks using a parallel hybrid metaheuristic on the computational grid
aCNRS/LIFL and INRIA, University of Lille, 59655 Villeneuve d’Ascq Cedex, France
Available online 12 September 2006.
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Abstract
Cellular network design is a major issue in mobile telecommunication systems. In this paper, a model of the problem in its full practical complexity, based on multiobjective constrained combinatorial optimization, has been investigated. We adopted the Pareto approach at resolution in order to compute a set of diversified non-dominated networks, thus removing the need for the designer to rank or weight objectives a priori. We designed and implemented a “ready-to-use” platform for radio network optimization that is flexible regarding both the modeling of the problem (adding, removing, updating new antagonist objectives and constraints) and the solution methods. It extends the “white-box” ParadisEO framework for metaheuristics applied to the resolution of mono/multi-objective Combinatorial Optimization Problems requiring both the use of advanced optimization methods and the exploitation of large-scale parallel and distributed environments. Specific coding scheme and genetic and neighborhood operators have been designed and embedded. On the other side, we make use of many generic features related to advanced intensification and diversification search techniques, hybridization of metaheuristics and grid computing for the distribution of the computations. They aim at improving the quality of networks and their robustness. They also allow, to speed-up the search and obtain results in a tractable time, and so efficiently solving large instances of the problem. Using three realistic benchmarks, the computed networks and speed-ups on different parallel and/or distributed architectures show the efficiency and the scalability of hierarchical parallel hybrid models.
Keywords: Cellular network design; Metaheuristics; Hybrid metaheuristics; Parallel computing; Grid computing
Fig. 1. Relationships on a working area between STPs and TTPs.
Fig. 2. Signals are considered differently at each reception point: best signal, handover signals and interference.
Fig. 3. Architecture of the ParadisEO framework.
Fig. 4. Architecture of the DEMARNO framework.
Fig. 5. Application of S-metric to the Pareto frontier found by cooperative/independent EAs (instance Arno 1.0).
Fig. 6. Iterative application of the LS starting from three random solutions (instance Arno 1.0).
Fig. 7. Evolution of the efficiency of the LS to find new non-dominated solutions during the optimization process.
Fig. 8. Cumulative CPU time allocated to the EA and the LS during the search.
Fig. 9. Speed-ups of the (a)synchronous parallel evaluation models (Instance Arno 1.0).
Fig. 10. Speed-ups of the synchronous parallel decomposition model (Instance Arno 1.0, Arno 3.0 and Arno 3.1).
Fig. 11. A parallel hybrid metaheuristic designed in DEMARNO with ParadisEO using several hierarchical layers of parallelization and hybridization.
Fig. 12. Graphical convergence of the elite of Pareto Optimal solutions found during the search function of the number of generations (Arno 1.0).
Fig. 13. Numerical convergence of the elite of Pareto Optimal solutions found during the search function of the number of generations (Arno 1.0). Efficiency bases on the S-metric.
Fig. 14. Highway instance (Arno 1.0). A random cellular network taken from the archive of solutions after the convergence of the metaheuristic has been reached.
Fig. 15. Urban instance (Arno 3.0). A random cellular network taken from the archive of solutions after the convergence of the metaheuristic has been reached.
Fig. 16. Urban instance (Arno 3.1). A random cellular network taken from the archive of solutions after the convergence of the metaheuristic has been reached.
Table 1.
Some parameters characterizing the tackled instances

Table 2.
Discretized engineering parameters

Table 3.
Mean CPU time to evaluate a network for different instances and scenarios as the wave propagation factor is computed from scratch or previously loaded from a matrix

Table 4.
Modeling of the basic asynchronous Steady-State EA

Table 5.
Parameters setting the flow of migrations

Table 6.
Some information characterizing the Local Search optimization for the three tackled instances (Opteron 2.2 GHz)

Table 7.
Some parameters setting the behavior of the Local Search

Table 8.
Numerical results for the execution of the parallel hybrid metaheuristic applied to instance Arno 1.0 on a dedicated cluster

Table 9.
Numerical results for the execution of the parallel hybrid metaheuristic applied to instance Arno 3.0 on a dedicated cluster

Table 10.
Numerical results for the execution of the parallel hybrid metaheuristic applied to instance Arno 3.1 on a metacomputing platform of non-dedicated and heterogeneous workstations
