Combinatorial Optimization Algorithms for Radio Network Planning

Special Issue on Combinatorics and Computer ScienceInternational audienceThis paper uses a realistic problem taken from the telecommunication world as the basis for comparing different combinatorial optimization algorithms. The problem recalls the minimum hitting set problem, and is solved with greedy-like, Darwinism and genetic algorithms. These three paradigms are described and analyzed with emphasis on the Darwinism approach, which is based on the computation of epsilon-nets

Combinatorial Optimization Algorithms for Radio Network Planning

An extended version of this paper was published in the Journal of Theoretical Computer Science (TCS), Special Issue on Combinatorics and Computer Science, 265(1):235-245, 2001. See http://hal.archives-ouvertes.fr/hal-00346034/fr/International audienc

Decomposition, Reformulation, and Diving in University Course Timetabling

In many real-life optimisation problems, there are multiple interacting components in a solution. For example, different components might specify assignments to different kinds of resource. Often, each component is associated with different sets of soft constraints, and so with different measures of soft constraint violation. The goal is then to minimise a linear combination of such measures. This paper studies an approach to such problems, which can be thought of as multiphase exploitation of multiple objective-/value-restricted submodels. In this approach, only one computationally difficult component of a problem and the associated subset of objectives is considered at first. This produces partial solutions, which define interesting neighbourhoods in the search space of the complete problem. Often, it is possible to pick the initial component so that variable aggregation can be performed at the first stage, and the neighbourhoods to be explored next are guaranteed to contain feasible solutions. Using integer programming, it is then easy to implement heuristics producing solutions with bounds on their quality. Our study is performed on a university course timetabling problem used in the 2007 International Timetabling Competition, also known as the Udine Course Timetabling Problem. In the proposed heuristic, an objective-restricted neighbourhood generator produces assignments of periods to events, with decreasing numbers of violations of two period-related soft constraints. Those are relaxed into assignments of events to days, which define neighbourhoods that are easier to search with respect to all four soft constraints. Integer programming formulations for all subproblems are given and evaluated using ILOG CPLEX 11. The wider applicability of this approach is analysed and discussed.Comment: 45 pages, 7 figures. Improved typesetting of figures and table

Radio Network Planning with Combinatorial Optimization Algorithms

International audienceFuture UMTS radio planning engineers will face difficult problems due to the complexity of the system and the size of these networks. In the STORMS project, a software for the optimisation of the radio network is under development. Two mathematical models of the radio planning problem are proposed. Two software prototypes based on these models are described with the first experimental and comparative results

Object-oriented parallel software for radio wave propagation simulation in urban environment

The objective of the European project STORMS (Software Tools for the Optimization of Resources in Mobile Systems) is to develop a software tool to be used for design and planning of the future Universal Mobile Telecommunication System (UMTS). In this context the ParFlow method permits the simulation of outdoor radio wave propagation in urban environment, modeling the physical system in terms of the motion of fictitious microscopic particles over a lattice. This paper gives an overview of the Parflow method, and reports the design, the implementation, and the performance analysis of ParFlow++, an object-oriented irregular parallel software for urban outdoor radio wave propagation prediction

Radio Network Planning with Combinatorial Optimization Algorithms

International audienceFuture UMTS radio planning engineers will face difficult problems due to the complexity of the system and the size of these networks. In the STORMS project, a software for the optimisation of the radio network is under development. Two mathematical models of the radio planning problem are proposed. Two software prototypes based on these models are described with the first experimental and comparative results