How It Fits Together
Steps in the Construction of a Visualyse Simulation
The flexibility of Visualyse means that there is no fixed prescription for setting up and analysing spectrum sharing scenarios. In addition, the number of other uses of the tool mean that there are very many ways you can begin to use the software.
A prerequisite to starting up the simulation is that have a clear idea of the results you are looking for and have a full description of both your wanted and interfering systems.
You need to know the RF, geometric and dynamic characteristics of both systems, and have some understanding of how these characteristics can be represented in Visualyse. This understanding can be gained by reviewing the User Guide, or from the example files and related document provided with Visualyse.
However, if you follow the prescription below you will be able to set up Visualyse to produce C/N+I, C/I and I/N results within a matter of hours.
The recommended steps involved in the creation and analysis of a spectrum sharing scenario are listed below:
- Define a library of Antennas that will be used
- Create the Stations, using Station Groups and Wizards where appropriate
- Define a library of communications carriers via the Carrier dialog
- Set up your Propagation Environments via the Propagation menu
- Set up communications Links – both wanted and interfering – using Link Groups and Wizards where appropriate
- Set up Interference Paths, where wanted and interfering Links are specified
- Define run duration and time step size using the Time Settings option on the Simulation menu
- Set up the Output you are interested in via the Output menu
- Run the simulation
- Analyse the results via the graphs, watch and table windows, and the various map views.
Location of Key Parameters
In the calculation of C, I, N, C/I, C/N, C/(N+I) and I/N there are a number of key parameters that are defined by your input data. In Visualyse it is sometimes possible to define these parameters in more than one place – this ensures that the software remains more flexible without becoming overly complex. It does, however, sometimes lead to confusion in new users because not every parameter in every dialog is used in the interference calculation.
This section describes where the basic link budgets parameters are or can be defined, and the configuration options under which the parameter will be used.
Wanted and interfering Links are defined in exactly the same way
| Parameter | Where Defined |
|---|---|
| Transmit Antenna Gain | The antenna gain is a combination of the peak gain plus the relative gain in the direction of interest. Both of these are defined in an Antenna object. |
| Transmit EIRP | The usual way to define the Link EIRP as a combination of Link power plus Antenna peak gain1 |
| Path Loss | The path loss depends on the propagation model selected and the environmental parameters, defined via the propagation menu. |
| Link Power | Power is defined in the Link dialog. |
| Spectral Density | By a combination of Link power and the bandwidth of the carrier used by the Link. |
| Carrier Bandwidth | The bandwidth is defined in the edit Carrier dialog. There are two values, the occupied bandwidth and the allocated bandwidth. |
| Bandwidth Overlap Factors | The calculation of the C/I ratio can be done in number of ways as defined in the Interference Path. |
| Central Frequency | The central frequency is defined in the Link dialog. In the Interference Paths dialog, it is possible to force the wanted and interfering carriers to be co-frequency. This has the effect of shifting the interfering carrier to be on the same central frequency as wanted carrier. |
| Frequency overlap | The frequency overlap is calculated automatically based on the wanted and interfering carrier central frequencies and bandwidth. |
| Wanted (or victim) Links | The wanted Link is selected in the Interference Path dialog. A Link can be selected in multiple Interference Paths. Interference levels on a Link will be aggregate values due to all Interfering Links on all Interference Paths. |
| Interfering Links | The interfering Links are selected in the Interference Path Dialog |
| Polarisation Advantage | Polarisation advantage is defined in the Interference Path dialog. |
A second is using the default values associated with the Antenna. The Link dialog has options to select either the default Antenna value or the Link power.