wiki:Manual/Algorithms/Basics/CoverageRadius

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1. Relative location of VLR / VLT and ILR / ILT (Coverage radius)

Coverage radius is the radius between the transmitter and the receiver. It applies for both the VLT->VLR and ILT->ILR. It should not be confused with the simulation radius.

The calculation of the relative positioning (azimuth / elevation) of the VLR or the ILR depends on 3 available options:

  • it may be a user-defined constant,
  • or it may be calculated by the EGE at the start of snapshots generation, assuming:
    • Noise-limited network operation, or
    • Traffic-limited network operation.

1.1 User-defined case

You can directly enter the value of the coverage radius


1.2 Noise-limited network case

In this case it is considered that the coverage of the transmitter is limited only by propagation losses and other elements of link budget, with received signal operating at the very sensitivity limit. In this case the maximum coverage radius may be obtained by reverting the following equation:

Where:

  • - propagation loss not including slow fading, i.e. path loss without variations option;
  • - slow fading margin for X% coverage loss;

The availability Y of the system is linked to the coverage loss through the simple relation Y = 1 - X. Assuming that slow fading can be approximated by a log-normal distribution, the solution would be equivalent to finding zero points of the following function:

where Q(x) is the inverse complementary cumulative normal distribution function.

Finding the zero of function g is achieved through the regula-falsi method used in logarithmic scale which should yield a better precision. The solution of such a method is described by:



Note: The input parameter of the Noise-limited network interface are set to zero by default in purpose to allow the user to define the radius independently from some parameters set elsewhere in the link.

1.3 Traffic-limited network case

In this case the coverage radius is derived from the traffic parameters of the transmitter, defined in the scenario, using following formula:

2. Example of relative location of transceivers within a link

If the correlation mode for the considered path is set to correlated then no calculation is required since the relative location is determined by dX/dY parameters entered by the user in the scenario.

If the correlation mode is set to uncorrelated, then the relative location is calculated as follows:

  • Trial of the distance factor according to the 'Path distance factor' distribution function set in the scenario (note that may be constant as well);
  • Calculation of the distance as the product of the coverage radius of the transmitter of the considered link (calculated once for all snapshots before the start of the simulation or set fixed by the user in the scenario) by the above-mentioned distance factor;
  • Trial of the transmitter-to-receiver angle according to the 'Path azimuth' distribution function set in the scenario (may be constant).

Then, assuming that the absolute position of one of the transceivers is known (established with reference to another link, depending on the It-Vr path correlation settings), the position of the other element in given link could be easily established using the above results on distance-angle inside the link.

Note: This information does not apply to placement of links in CDMA/OFDMA systems, which are modelled using specific algorithms.

scenario layoutworkspace
scenario 1 workspace
scenario 2 workspace
scenario 3 workspace

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