OPNET is one of the widely used modelling and simulation software packages in the telecommunications industry for planning, design, and research and development. In the wireless modeller module, it uses common propagation models to model radio propagation. It is also possible for users to include their own custom made propagation models to run as part of simulations.This dissertation covers the study done to integrate rain fade into OPNET by including in one of the propagation models, the ability to access channel information from an external file and using the data to calculate attenuation along the simulated radio path.First the operation of OPNET is summarised, and a simulation model is developed to demonstrate some functions and results available when performing studies with the software.Synthesised fine scale rain fields data, for use as the channel model data, was created. The measurement data was obtained from the Chilbolton Radar Interference Experiment, CRIE, which was made over a period of two years (1987-1989) at Chilbolton Advanced Meteorological Radar (CAMRa) station.Then, the free space propagation model available in OPNET was modified to read rain fade time series data from an external file, and to use the data to scale radio signal levels between transmitter and receiver models in simulations. Shared libraries to enable the running between OPNET and the customised propagation model were to be created, but due to limited time, these were not completed. Hence the customised model was not tested in OPNET.It is presented, as recommendations for future work to further explore the capabilities of OPNET, and to complete the creation of the shared libraries not achieved in this project, and finally to test the propagation model with rain fade by investigating the availability of route diverse radio link implemented as a Fade Mitigation Technique
