wiki:Manual/Algorithms/Basics/RelativeLocationBetweenLinks

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Relative location of VLR with ILT (Simulation radius)



The calculation of the relative location (azimuth / elevation) of the Victim Receiver (VLR) and the Interfering Transmitter (ILT) depends on the choice of the correlation mode set for the VLR-ILT path in the scenario:

  • None, i.e. non-correlated mode
  • Uniform density mode
  • Closest interferer mode
  • Correlated distance, in which case the relative location is explicitely defined by the dX/dY values given in the scenario.

In addition to these interference distributions selections, you are able to set the reference point of these distributions with a spatial offset (DeltaX and DeltaY). The option "Set the ILR at the center of the ILT distribution" overwrite the settings in the transmitter to reveicer path of the interferer.


Relative position of the distributed interferers

None

The None mode usea the notion of simulation radius of the interfering transmitter which defines the circular area where the ILTs are spread.

If the correlation mode for the IT-VR path is set to None, the relative location is calculated as follows:

  • Trial of the path distance factor according to the scenario setting for the VR-IT path;
  • Calculation of the absolute distance as a product of the user-defined simulation radius (constant value defined by the user in VR-IT path settings) and the above path distance factor;
  • Trial of the path azimuth angle according to the relevant distribution set in the scenario for VR-IT path. Based on that relative angle-distance information, the absolute positions could be established with reference to one known position (usually VR in this case).

Note: If in the VR-IT path settings, the Number of active transmitters is set to more than one, this will result in spatially-independent generation of the specified number of ITs, whereas the resulting total iRSS strength will be obtained by simple power summation of the individual iRSS signal values.

Uniform density mode

The uniform density mode use the notion of simulation radius of the interfering transmitter which defines the circular area where the ILTs are spread.

If the correlation mode for the VR-IT path is set to Uniform density, the relative location is calculated as follows:

  • Trial of the path distance factor according to an implicit uniform polar distance distribution between 0 and 1;
  • Calculation of absolute distance as product of the simulation radius for the VR-IT path (calculated as described below) and the above path distance factor;
  • Trial of the path azimuth angle of the IT-VR path according to relevant distribution assigned to this parameter in VR-IT path scenario settings.

In this case the IT-VR path simulation radius is calculated at the very beginning of EGE cycle and applied in all snapshots:

where:

  • nactive - number of active transmitters set in the scenario for IT-VR path;
  • densitactive - calculated product of active transmitters density:

  • densit - density of transmitters, 1/km2, user-defined parameter in the table Interferers density of VR-IT path;
  • Pit - probability of transmission, user-defined parameter;
  • activityit(time) - user-defined temporal activity function (a look-up table). The time value used for calculation is specified in parameter time.
  • time - parameter defining which of the values in the above activity function should be used in calculations (e.g. if the activityit(time) function contains three pairs: (1;0.5), (2;0.7), (3; 0.9), and the time parameter is set to 2, then the activityit(time) function will be returning value 0.7).

Based on that relative angle-distance information, the absolute positions could be established with reference to one known position (usually VR in this case).

Note 1: If in the VR-IT path settings, the Number of active transmitters is set to more than one, this will result in spatially-independent generation of the specified number of ITs, whereas the resulting total iRSS strength will be obtained by simple power summation of the individual iRSS signal values.

Note 2: When you set up your simulation, and the relevant input factor is the simulation radius, it is recommended to use the “None” mode instead of the “Uniform density” mode (In that case, you may simulate the activity of the transmitter, e.g. duty cycle, using the distribution of the transmit power). If you are more interested to consider as an input the density of the user (i.e. without setting the simulation radius as input), it is recommended to use the “Uniform density” mode.

Closest interferer

If the correlation mode for the VR-IT path is set to Closest interferer, the relative location is calculated as follows :

  • Trial of the path azimuth angle of the IT-VR path according to relevant distribution assigned to this parameter in VR-IT path scenario settings;
  • Repeat trial of the absolute distance (not the distance factor) between VR-IT according to an implicit Rayleigh distribution, until the result of this trial produces value smaller than the protection distance specified in the scenario.

VLR and ILT positioning reference point

  • For the path azimuths in the VLT-VLR (left) and ILT-ILR links (right), the reference point is a transmitter and the angle is from the positive direction of Ox axis to the path towards a corresponding receiver in a link.

  • For the path azimuth used in describing relative VLR-ILT positioning, the reference point is at the victim link and the angle is between the positive direction of Ox axis and the path towards the It. You can select either the VLT or the VLR as the origin.

These principles of defining azimuth angles are illustrated in the following picture.

By means of example, the geometric positioning of victim and interfering systems in the above figure could be programmed within the SEAMCAT interference scenario in the following way:

  • ILT-VLR path: relative location mode: none, VLR is selected as reference, path azimuth - constant at 45 deg, appropriate distance parameters;
  • ILT-ILR path: path azimuth: 0/90 deg;
  • VLT-VLR path: path azimuth: 0/90 deg;

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