You are here: Manual / PropagationModels / Longley Rice propagation plug-in

---

Longley Rice propagation model plugin

Introduction

The Longley-Rice (Area prediction mode) propagation model was developed as SEAMCAT plug-in in the  National Telecommunications Institute (Poland) in co-operation with the  Wrocław University of Technology. The task was performed under Research Project of the Polish Ministry of Science and Higher Education entitled: Next generation teleinformatics services - technology, application and market aspects (no. PBZ-MNiSW-02/II/2007).

It uses two types of plug-in available in SEAMCAT: Propagation model plug-in and also post processing plug-in. The second one is needed for setting input parameters values. The results has been pre-tested and confirmed that they are consistent with expected value.

The Longley-Rice (Irregular Terrain Model) propagation model in area prediction mode (i.e. no need for terrain profile details to make a path loss calculation) was developed for SEAMCAT. The propagation model can be used in a wide frequency range: 20 MHz – 20 GHz and is widely used in the USA and other countries.

The ITM model returns predicted median attenuation of a radio signal, regarding not only statistical terrain, system, climate parameters but also variability of the signal in time and in space, assuming a level of confidence. Longley-Rice computes path loss into three regions:

• Line-of-sight range,
• diffraction range and
• scatter range (In distance between 1 – 2000 km).

ITM model is based on electromagnetic theory and on statistical analysis, the original model was developed in 1960’s in the USA. Further details of the model can be found here.

(If you have comments they may be sent to STG ( ''SEAMCAT Technical Group'') or directly to Mr. Jean-Philippe Kermoal (kermoal@…) chairman of the STG.)

Plugins

The source code (.java files) are available here and the plugin (several .class files) is freely downloadable from here.

Test/calibration

Calibration test made by the National Telecommunications Institute can be found here.

How to load the plugins

With embeddement

1. The .class files have to stored in a .zip or a .jar file anywhere you want on your machine. You can even put the propagation model and the postprocessing plugin .class file in the same .zip or .jar files.
2. In SEAMCAT, press Library -> Propagation model plugins -> Add ->

3. Select the .jar or .zip file to be embedded in your library. You will see that the name of the file you have embedded is appearing under the choose button.

4. In Fully Qualified Classname form write: LongleyRice (it should appear as you type and the red background should disappear). The Name/Reference will automatically update as you type in the Qualified Classname form. Note that you can edit this field if you want to.

5. when you click ok, you will see that the propagation model that you have selected is embedded. This will allow you to share your workspace with others without sending separately your propagation model.

6. Press Library -> Post processing plugin -> Add -> In Fully Qualified Classname form write: ConfigureLongleyRice, as for the propagation model interface, the Name/Reference populates as type and you can edit it.

7. You can now set your propagation model in the victim or the interfering link.

Without embeddement

1. The .class files have to be copied to the SEAMCAT directory (i.e. C:\Documents and Settings\{user}\seamcat\plugins).
2. Next, launch SEAMCAT
3. Press Library -> Propagation model plugins -> Add ->

4. directly type the name of the propagation model class file (i.e. do not select the embeddement feature). You will see that the name of the file you have embedded is appearing under the choose button.

5. In Fully Qualified Classname form write: LongleyRice (it should appear as you type). The Name/Reference will automatically update you type.

6. when you click ok, you will see that the propagation model is loaded but without embeddement. If you want to share your workspace with others do not forget to send the .class file too.
7. Press Library -> Post processing plugin -> Add -> In Fully Qualified Classname form write: ConfigureLongleyRice

Using Longley-Rice model

To use the plugin in the scenario you should select the Library plugin-class and select Plugin in propagation model selection



Then you must add the postprocessing plugin by select Workspace -> Post processing plugins, and configure it.



You can set different links (victim and Interfering) using different configuration of the Longley-Rice plugins . The plugin allows up to 99 links to be configured differently(i.e. the highest ID number should be 99).

To use the plugins for a particular configuration of a link, please provide the same ID number in the fields:

• Param1 (propagation model plugin)
• Propagation Model ID (post processing plugin)

Params 2 and 3 of the propagation model plugin are not use.

The number of post processing plugin instances in a particular SEAMCAT scenario should be the same as numbers of links in which Longley-Rice propagation model is used. The rest of parameters should be in the range described in chapter two (Input parameters).

The mode of variability form is described by 4 value:

1. Single
2. Individual
3. Mobile
4. Broadcast

It is important to accept every writing value by pressing enter.