# 5.4 Transmitter to Receiver Path # Introduction 3 elements form the path between the VLR and the VLT or the ILR and ILT as illustrated in Figure 148. [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/ZUDypHSuzlwwO6Iz-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/ZUDypHSuzlwwO6Iz-image.png) **Figure 148: Transmitter to Receiver Path illustration** ![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/YTAuBTBWjEv8ybzH-image.png) **Figure 149: Transmitter to Receiver Path GUI** # 5.4.1 Relative location - When the Correlated distance option is checked, the positions of the receiver and transmitter are geographically fixed with respect to each other (e.g. co-located or constantly spaced base stations). The transmitter is considered a reference centre. - When the correlated distance is unchecked, the receiver is randomly moving around the transmitter. There are 2 primary options to define type of mutual placement of VLR with respect to VLT. See ANNEX 12: for further details on the algorithm and conventions. ![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/70SixnzSAJx9O9hy-image.png)
**Figure 150: Relative location panel**
**Table 15: Relative location GUI**
**Description** **Symbol** **Type** **Unit** **Comments**
**Correlation distance** - Boolean - When checked, the only the Delta X and Y are editable.
**Delta X** X Distribution Km Horizontal distance between the transmitter and receiver. It can be used to shift horizontally the distributed receivers.
**Delta Y** Y Distribution Km Vertical distance between the transmitter and receiver. It can be used to shift vertically the distributed receivers.
**Path azimuth** - Distribution Degree Horizontal angle for the location of the Rx respect to the Tx. If constant, the Rx’s location will be on a straight line. If not, the location of the Rx will be on an angular area. (See Annex A12.3)
**Path distance factor** - Distribution - Distance factor to describe path length between the Tx and the Rx. If the path factor is constant, the Rx will be located on a circle around the Tx. (See Annex A12.2)
**Use of polygon** - Boolean - When this is checked, you can select other shape of deployement than the default circle
**Shape of the polygon** - Boolean - You can select between hexagon (6 sides), heptagon (7 sides), Octagon (8 sides), Pentagon (5 sides), Rectangle (4 sides) and Triangle (3 sides)
**Turn CCW** - Distribution Degree Allows to rotate counter clock wise the selected polygon
# 5.4.2 Coverage radius A coverage radius is calculated for both the victim link and the interfering link. It is the [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/tGOkdPMyKZbZySrt-image.png) ](https://wiki.cept.org/uploads/images/gallery/2026-04/tGOkdPMyKZbZySrt-image.png)
for the victim link (VLR-VLT) and the [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/Pz0NlP4oCrx93MUk-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/Pz0NlP4oCrx93MUk-image.png) for the interfering link (ILR-ILT) (see Annex A13.1). The receivers will be randomly deployed within the area centred on the transmitter and delimited by the coverage radius if the non-correlated option is selected. Three different modes are available for calculating the maximum radius . - **User-defined radius** allows directly entering the maximum radius (See Annex A13.1.1); [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/6nlQ8iTyprzHVyYn-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/6nlQ8iTyprzHVyYn-image.png) ![](blob:https://ecowiki.atlassian.net/08192573-10ef-4f8e-9d02-477ac9a3640a#media-blob-url=true&id=c9954758-0f29-4abb-acba-d35e38ebfa9b&collection=contentId-494309&contextId=494309&width=406&height=252&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)**Figure 151: User-defined coverage radius dialog box** **Table 16: Description on User-defined coverage radius**
**Description** **Symbol** **Type** **Unit** **Comments**
**Coverage radius** Rmax Scalar km The coverage radius defines the coverage of the system, i.e. the maximum distance between an ILT and a ILR or between a VLT and a VLR. The origin point of the coverage radius is logically the VLT or the ILT.
- The **noise-limited network** option will calculate the coverage radius based on the formula for noise-limited network. If this option is chosen, a set of input boxes will appear below allowing the user to enter specific parameters required for this calculation. In this case it is considered that the coverage of the transmitter is limited only by propagation losses and other elements in thelink budget, with received signal operating at the sensitivity limit. The details of the calculation are given in Annex A13.1.2.
[![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/LyPyaWXO6NLISBts-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/LyPyaWXO6NLISBts-image.png) **Figure 152: Noise limited network coverage radius dialog box** The coverage radius in the noise-limited network is defined by the parameters of Table 17. Note that the input parameters for the Noise-limited network interface are set to zero by default in order to independently define the radius from some parameters set elsewhere in the link.
**Table 17: Description of the Noise limited network coverage radius user interface**
**Description** **Symbol** **Type** **Unit** **Comments**
Reference antenna height (receiver): h0 Scalar m The height used for coverage radius calculations. If a distribution is used to define the real height, the coverage radius would be different in each trial, here the value may be fixed.
Reference antenna height (transmitter): h0 Scalar m The height used for coverage radius calculations.
Reference frequency fVLR Scalar MHz
Reference power PVLT Scalar dBm
Minimum distance km
Maximum distance km
Availability %
Fading standard deviation dB
Reference percentage of time %
**Traffic-limited network** option will calculate the coverage radius, based on the formula for traffic-limited network. If this option is chosen, a set of input boxes will appear below allowing user to enter specific parameters required for this calculation (See Annex A13.1.3). [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/iFRbFB8E4AueGJSZ-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/iFRbFB8E4AueGJSZ-image.png)
![](blob:https://ecowiki.atlassian.net/d911aba4-be6d-4a1f-8824-ded4d8796881#media-blob-url=true&id=73b92f7d-369d-4f5e-9055-558014256f46&collection=contentId-494309&contextId=494309&width=410&height=293&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)**Figure 153: Traffic limited network coverage radius dialog box**
**Table 18: Description of the traffic limited network coverage radius user interface**
**Description** **Symbol** **Type** **Unit** **Comments**
**Density**
![](blob:https://ecowiki.atlassian.net/9b506f28-f163-4ec2-a5ad-9155f2f39588#media-blob-url=true&id=82ca75d2-5395-4afb-ae91-cf6a23300f9f&collection=contentId-494309&contextId=494309&width=50&height=27&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)
Scalar 1/km2 Maximum number of active transmitters per km2
**Number of channels**
![](blob:https://ecowiki.atlassian.net/862471e1-3791-4b77-8e69-8352b151b8a5#media-blob-url=true&id=23630831-cf3a-4c1d-822a-bf2aa0f696c8&collection=contentId-494309&contextId=494309&width=44&height=27&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)
Scalar Number of frequency channels of the system
**Number of users per channel**
![](blob:https://ecowiki.atlassian.net/9690b5d5-a625-40f4-a8f6-0c0b7da31e0b#media-blob-url=true&id=3302fe3f-117f-456c-b7a1-e1a8048f3063&collection=contentId-494309&contextId=494309&width=71&height=28&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)
Scalar Number of MS per frequency channel
**Frequency cluster**
![](blob:https://ecowiki.atlassian.net/fd0ba487-f149-444d-b56d-4ff7455d8094#media-blob-url=true&id=707bdac2-378d-450f-a441-57803f3ca70a&collection=contentId-494309&contextId=494309&width=84&height=28&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)
Scalar Size of a group of frequency channels. See Figure 180 for illustrative details.
The consistency of this parameter should be verified against the sensitivity, so that if a receiver is placed at given distance (e.g. at the maximum coverage radius) the received power is higher than the sensitivity for a reasonable percentage of occurrences (availability).
# 5.4.3 Local environment The percentage of transceivers being indoor and outdoor can be selected thanks to this panel. It will work in combination with the chosen propagation model that you will select. By default the transmitter and receiver are located outdoor. For each elements of the link, it is possible to add [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/9PThBUQugUtcxFwJ-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/9PThBUQugUtcxFwJ-image.png) or remove [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/dfVtghpGfZjjf3OO-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/dfVtghpGfZjjf3OO-image.png) a probability of indoor. [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/oWHViCZ0FRD9g2Rr-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/oWHViCZ0FRD9g2Rr-image.png)**Figure 154: Example of setting up the outdoor/indoor ratio** You can edit the field by double cliking
[![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/ofM0c9iyfqyCp0RQ-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/ofM0c9iyfqyCp0RQ-image.png)**Figure 155: Graphical interface to edit the probability, wall loss and associated standard deviation** **Table 19: Local environment and wall loss**
**Description** **Symbol** **Type** **Unit** **Comments**
**Local environment: Receiver** Indoor/ outdoor - - Environment of the receiver antenna: outdoor, indoor It is used for both VLR and ILR.
**Local environment: Transmitter** Indoor/ outdoor - - Environment of the transmitter antenna: outdoor, indoor It is used for both VLT and ILT.
**Probability** - Scalar % Probability that a Tx or Rx is located indoors or outdoors.
**Wall loss** or Scalar dB Attenuation of external walls separating indoor and outdoor propagation environments. This parameter is associated to the selected propagation model.
**Std. dev.** or Scalar dB Wall loss stdandard deviation (indoor - outdoor) Wall loss standard deviation associated to the selected propagation model.
Note that when opening a workspace created prior to SEAMCAT version 5, all settings are mapped to the current SEAMCAT version running on your machine. As the parameter local environment didn’t exist before version 5, a warning may appear indicating that “local environments are skipped for multiple interfering links”. This means that SEAMCAT was not able to automatically set the parameters of the local environments (most likely due to a scenario with multiple interferers). Therefore, there is a need to edit the local environment manually. [![image.png](https://wiki.cept.org/uploads/images/gallery/2026-04/scaled-1680-/wXgShLZvV9pMApsl-image.png)](https://wiki.cept.org/uploads/images/gallery/2026-04/wXgShLZvV9pMApsl-image.png)
![](blob:https://ecowiki.atlassian.net/75f5b356-c4f9-4934-a8bb-460ba4a9a9db#media-blob-url=true&id=61970a05-26f2-487f-9ac2-fa1b3e02d8de&collection=contentId-494313&contextId=494313&width=488&height=187&alt=&clientId=113268fe-fe5b-4bc3-8ff3-07965dbf1d18)F**igure 156: Migration warning on the local environment**
# 5.4.4 Propagation Model A suitable propagation model can be selected to be applied when calculating signal loss along the path between transmitters and receivers. Further information on propagation models are presented in detail in ANNEX 17.