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General Information

The following list shows what general information to list with a scenario. Some information is mandatory, some is optional. Optional information is marked by an asterisk ('*').

Scenario identifier
 The scenario identifier must be unique among all scenarios. (By making the identifier part of the file content rather than the file name, we can get rid of the various restrictions imposed by file naming conventions of the different operating systems used by the subgroup-members.)
*Scenario annotation
  The contributor of a scenario may want to add some comments for the human reader of the file. Useful comments can be a description of the scenario's origin and what is problematic/typical about the scenario.
Network type
  The network type indicates whether the scenario is a GSM900 or GSM1800 network.
  We assume that the spectrum is an interval. In case the set of available channels is not an interval, the spectrum is the interval ranging from the lowest available channel to the highest available channel. The channels not available within that range are listed as globally blocked.
*Globally blocked channels
  A channel is globally blocked if it is in the spectrum but not available for frequency assignment for some reason.
Co-site separation
  The co-site separation is the minimum separation necessary between channels operated on carriers at the same site. We assume that the co-site separation is the same for all sites.
Default co-cell separation
 The co-cell separation is the minimum separation necessary between
[4] channels used by carriers in the same cell. Due to different transceiver technologies, the co-cell separation may vary from cell to cell. Here, we define a default minimum separation that should hold for most of the cells. In case there are different requirements for some cells, those can be specified in the corresponding cell descriptions.
Handover separation
  There are handover relations between cells. We have to specify what handover separation is required like it is done in Table 4.
*Minimal significant interference
  All known interference relation between cells should be listed in a scenario description. Hence, relations with very small interference ratings are included in the list. This parameter will be used as a threshold to delete interference ratings below its value prior to frequency planning. The reason for listing small interference ratings anyway is that those relations will provide additional structural information on the scenario.
*Maximal tolerable interference
  The value of this parameter is used as an upper bound on the maximal admissible interference. Interference ratings exceeding this threshold are ruled out by introducing a separation requirement with a sufficiently high value, i.e., a minimum separation of one is used to rule out co-channel interference and a minimum separation of two is used to rule out co- and adjacent-channel interference. Again, ruling out intolerably high interference by inserting suitable separation requirements should be done only prior to frequency planning, since the interference ratings carry more information for structural investigations than a separation requirement.
Demand model
  For our scenario Tiny, the absolute number of carriers per cell is given. This will be called the absolute demand model. A more flexible approach is called normalized traffic model [1]: For each cell the expected traffic is given. These traffic figures are used to derive the number of carriers per cell. Since traffic data will often be confidential, normalized traffic is used. The normalized traffic figures are determined in such a way that the relations between the cells come out right. The actual demand of carriers per cell depends on two parameters: a scaling factor and a blocking rate. (Reasonable ranges for values of these parameters can be given in the annotation.) The carrier demand in a cell is computed by means of the Erlang-B formula [2] where the scaled normalized traffic and the blocking rate are inserted. By changing the values of the scaling factor and the blocking rate, the number of necessary carrier per cell changes. (This happens in a more realistic way than by scaling the figures in the absolute demand model.)
Site locations
  For a graphical representation of a scenario, Cartesian coordinates of the site locations are extremely helpful. The value of this parameter indicates whether site locations are supplied. Some operators may not want to supply the precise coordinates of their (projected) sites. Yet, the experience is that a graphical representation of a network can be very useful in the design of algorithms for frequency assignment and the structural analysis of scenarios. However, approximate coordinates are usually sufficient for our purposes. Therefore, we strongly support that scenarios are given including Cartesian coordinates of site locations--possibly with the coordinates perturbed and/or translated.

next up previous
Next: Cells Up: Discussion of scenario parameters Previous: Discussion of scenario parameters
Andreas Eisenblaetter