@inproceedings{EisenblaetterKochMartinetal.2003, author = {Eisenbl{\"a}tter, Andreas and Koch, Thorsten and Martin, Alexander and Achterberg, Tobias and F{\"u}genschuh, Armin and Koster, Arie M.C.A. and Wegel, Oliver and Wess{\"a}ly, Roland}, title = {Modelling Feasible Network Configurations for UMTS}, booktitle = {Telecommunications Network Design and Management}, editor = {Anandalingam, G. and Raghavan, S.}, publisher = {Kluver}, year = {2003}, language = {en} } @inproceedings{EisenblaetterFuegenschuhGeerdesetal.2003, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Geerdes, Hans-Florian and Junglas, Daniel and Koch, Thorsten and Martin, Alexander}, title = {Optimisation Methods for UMTS Radio Network Planning}, booktitle = {Operation Research Proceedings 2003}, editor = {Ahr, Dino and Fahrion, Roland and Oswald, Marcus and Reinelt, Gerhard}, publisher = {Springer}, doi = {10.1007/978-3-642-17022-5_5}, pages = {31 -- 38}, year = {2003}, language = {en} } @misc{BorndoerferEisenblaetterGroetscheletal.1997, author = {Bornd{\"o}rfer, Ralf and Eisenbl{\"a}tter, Andreas and Gr{\"o}tschel, Martin and Martin, Alexander}, title = {Frequency Assignment in Cellular Phone Networks}, doi = {10.1023/A:1018908907763}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-3044}, number = {SC-97-35}, year = {1997}, abstract = {We present a graph-theoretic model for the \emph{frequency assignment problem} in Cellular Phone Networks: Obeying several technical and legal restrictions, frequencies have to be assigned to transceivers so that interference is as small as possible. This optimization problem is NP-hard. Good approximation cannot be guaranteed, unless P = NP. We describe several assignment heuristics. These heuristics are simple and not too hard to implement. We give an assessment of the heuristics' efficiency and practical usefulness. For this purpose, typical instances of frequency assignment problems with up to 4240 transceivers and 75 frequencies of a German cellular phone network operator are used. The results are satisfying from a practitioner's point of view. The best performing heuristics were integrated into a network planning system used in practice.}, language = {en} } @misc{EisenblaetterFuegenschuhKochetal.2002, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Koch, Thorsten and Koster, Arie M.C.A. and Martin, Alexander and Pfender, Tobias and Wegel, Oliver and Wess{\"a}ly, Roland}, title = {Modelling Feasible Network Configurations for UMTS}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6837}, number = {02-16}, year = {2002}, abstract = {A model for the optimisation of the location and configuration of base stations in a UMTS network is described. The focus is primarily on modelling the configuration problem sufficiently accurate using mixed-integer variables and (essentially) linear constraints. These constraints reflect the limited downlink code capacity in each cell, the interference limitations for successful up- and downlink transmissions, the need for sufficiently strong (cell) pilot signals, and the potential gain for mobiles from being in soft(er) hand-over. It is also explained how to use the model as a basis for rating network configurations.}, language = {en} } @misc{EisenblaetterFuegenschuhGeerdesetal.2003, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Geerdes, Hans-Florian and Junglas, Daniel and Koch, Thorsten and Martin, Alexander}, title = {Optimization Methods for UMTS Radio Network Planning}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7637}, number = {03-41}, year = {2003}, abstract = {The UMTS radio network planning problem poses the challenge of designing a cost-effective network that provides users with sufficient coverage and capacity. We describe an optimization model for this problem that is based on comprehensive planning data of the EU project MOMENTUM. We present heuristic mathematical methods for this realistic model, including computational results.}, language = {en} } @misc{BorndoerferEisenblaetterGroetscheletal.1998, author = {Bornd{\"o}rfer, Ralf and Eisenbl{\"a}tter, Andreas and Gr{\"o}tschel, Martin and Martin, Alexander}, title = {The Orientation Model for Frequency Assignment Problems}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-5627}, number = {TR-98-01}, year = {1998}, abstract = {Mobile telecommunication systems establish a large number of communication links with a limited number of available frequencies; reuse of the same or adjacent frequencies on neighboring links causes interference. The task to find an assignment of frequencies to channels with minimal interference is the frequency assignment problem. The frequency assignment problem is usually treated as a graph coloring problem where the number of colors is minimized, but this approach does not model interference minimization correctly. We give in this paper a new integer programming formulation of the frequency assignment problem, the orientation model, and develop a heuristic two-stage method to solve it. The algorithm iteratively solves an outer and an inner optimization problem. The outer problem decides for each pair of communication links which link gets the higher frequency and leads to an acyclic subdigraph problem with additional longest path restrictions. The inner problem to find an optimal assignment respecting an orientation leads to a min-cost flow problem.}, language = {en} } @misc{EisenblaetterGeerdesKochetal.2004, author = {Eisenbl{\"a}tter, Andreas and Geerdes, Hans-Florian and Koch, Thorsten and Martin, Alexander and Wess{\"a}ly, Roland}, title = {UMTS Radio Network Evaluation and Optimization beyond Snapshots}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7903}, number = {04-15}, year = {2004}, abstract = {This paper is concerned with UMTS radio network design. Our task is to reconfigure antennas and the related cells as to improve network quality. In contrast to second generation GSM networks, \emph{interference} plays a paramount role when designing third generation radio networks. A known compact formulation for assessing the interference characteristics of a radio network as coupling relations between cells based on user snapshots is generalized to statistical average load. This enables us to overcome the notorious difficulties of snapshot-based network optimization approaches. We recall a mixed-integer programming model for the network design problem that is based on user snapshots and contrast it with a new network design model based on the average coupling formulation. Exemplarily focusing on the important problem of optimizing antenna tilts, we give computational results for a fast local search algorithm and the application of a MIP solver to both models. These results demonstrate that our new average-based approaches outperform state-of-the-art snapshot models for UMTS radio network optimization.}, language = {en} } @article{EisenblaetterGeerdesKochetal.2005, author = {Eisenbl{\"a}tter, Andreas and Geerdes, Hans-Florian and Koch, Thorsten and Martin, Alexander and Wess{\"a}ly, Roland}, title = {UMTS Radio Network Evaluation and Optimization beyond Snapshots}, volume = {63}, journal = {Mathematical Methods of Operations Research}, number = {1}, doi = {10.1007/s00186-005-0002-z}, pages = {1 -- 29}, year = {2005}, language = {en} } @article{BorndoerferEisenblaetterGroetscheletal.1998, author = {Bornd{\"o}rfer, Ralf and Eisenbl{\"a}tter, Andreas and Gr{\"o}tschel, Martin and Martin, Alexander}, title = {Frequency assignment in cellular phone networks}, volume = {76}, journal = {Annals of Operations Research}, publisher = {J. C. Baltzer AG, Science Publishers}, doi = {10.1023/A:1018908907763}, pages = {73 -- 93}, year = {1998}, language = {en} } @incollection{EisenblaetterFuegenschuhKochetal.2002, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Koch, Thorsten and Koster, Arie M.C.A. and Martin, Alexander and Pfender, Tobias and Wegel, Oliver and Wess{\"a}ly, Roland}, title = {Mathematical Model of Feasible Network Configurations for UMTS}, booktitle = {Telecommunications network design and management}, editor = {G. Anandalingam, S.}, publisher = {Kluwer}, pages = {1 -- 24}, year = {2002}, language = {en} } @inproceedings{EisenblaetterFuegenschuhGeerdesetal.2004, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Geerdes, Hans-Florian and Junglas, Daniel and Koch, Thorsten and Martin, Alexander}, title = {Integer Programming Methods for UMTS Radio Network Planning}, booktitle = {Proceedings of the WiOpt'04, Cambridge, UK}, year = {2004}, language = {en} } @article{EisenblaetterFuegenschuhFledderusetal.2003, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Fledderus, E. and Geerdes, Hans-Florian and Heideck, B. and Junglas, Daniel and Koch, Thorsten and K{\"u}rner, T. and Martin, Alexander}, title = {Mathematical Methods for Automatic Optimization of UMTS Radio Networks}, number = {D4.3}, editor = {Martin, Alexander}, publisher = {IST-2000-28088 MOMENTUM}, year = {2003}, language = {en} } @article{EisenblaetterGeerdesJunglasetal.2003, author = {Eisenbl{\"a}tter, Andreas and Geerdes, Hans-Florian and Junglas, Daniel and Koch, Thorsten and K{\"u}rner, T. and Martin, Alexander}, title = {Final Report on Automatic Planning and Optimisation}, number = {D4.7}, publisher = {IST-2000-28088 MOMENTUM}, year = {2003}, language = {en} } @inproceedings{BorndoerferEisenblaetterGroetscheletal.1996, author = {Bornd{\"o}rfer, Ralf and Eisenbl{\"a}tter, Andreas and Gr{\"o}tschel, Martin and Martin, Alexander}, title = {Stable-Set and Other Techniques for Frequency Assignment Problems}, booktitle = {Anais da I Oficina Nacional em Problemas de Corte \& Empacotamento}, publisher = {Universidade de S{\~a}o Paulo, Instituto de Matem{\´a}tica e Estat{\´i}stica}, pages = {17 -- 21}, year = {1996}, language = {en} }