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  <doc>
    <id>562</id>
    <completedYear/>
    <publishedYear/>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>reportzib</type>
    <publisherName/>
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    <completedDate>1998-04-03</completedDate>
    <publishedDate>1998-04-03</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">The Orientation Model for Frequency Assignment Problems</title>
    <abstract language="eng">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.</abstract>
    <identifier type="serial">TR-98-01</identifier>
    <identifier type="opus3-id">563</identifier>
    <identifier type="urn">urn:nbn:de:0297-zib-5627</identifier>
    <author>Ralf Borndörfer</author>
    <author>Andreas Eisenblätter</author>
    <author>Martin Grötschel</author>
    <author>Alexander Martin</author>
    <series>
      <title>ZIB-Report</title>
      <number>TR-98-01</number>
    </series>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Minimum-Cost Flow Problems</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cellular Radio Telephone Systems</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Frequency Assignment Problem</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Integer Programming</value>
    </subject>
    <collection role="ddc" number="000">Informatik, Informationswissenschaft, allgemeine Werke</collection>
    <collection role="msc" number="90B10">Network models, deterministic</collection>
    <collection role="msc" number="90B80">Discrete location and assignment [See also 90C10]</collection>
    <collection role="msc" number="90C10">Integer programming</collection>
    <collection role="institutes" number="">ZIB Allgemein</collection>
    <collection role="persons" number="borndoerfer">Borndörfer, Ralf</collection>
    <collection role="persons" number="groetschel">Grötschel, Martin</collection>
    <collection role="projects" number="eplus-FAP">eplus-FAP</collection>
    <file>https://opus4.kobv.de/opus4-zib/files/562/TR-98-01.ps</file>
    <file>https://opus4.kobv.de/opus4-zib/files/562/TR-98-01.pdf</file>
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