Are the simulation models used by researchers at each university unique to each university? Or use a specific common model?
I started working on OFDM research at university, but I'm at a loss as to how to create a simulation model. for exsample,pilot location, mutipath fading model,coding,...
"All models are wrong, but some are useful" - George Box, statistician
Your goal shouldn't be to exactly follow someone else's model or work but I think you'll be better off trying to do the following.
You learn about the background theory of the topic, then you understand how modern research is being done in that area, and then when you lay out your research problem the model to usually falls into place. Or it'll become clear if no past works directly relate and then you need to lay out assumptions and why you are making those assumptions so that others can understand and trust the validity of your modeling.
As far as you working on OFDM specifically, there are many papers on OFDM as well as material on the theory of it. Once you learned about OFDM (why use it? how are synchronization, channel estimation, equalization typically done? what assumptions do people usually make?), then you may explore how do modern research works explore OFDM. I think you'll find either people exactly use a published signal (IEEE 802 for WiFi, LTE/5G for cellular, etc.) or they closely model one so that its not a far stretch. This is to say, don't have your work revolve around something too obscure without justification.
Good research typically starts with a "state of the art" analysis. I.e. you are expected to read up on existing research and on models that are currently be used. You should assess and discuss them, in particular with respect to your specific problem or research area of interest.
In many cases you will find a suitable model you can expand on. That's one of the most fundamental ideas of research: "start with what's already there" or "don't re-invent the wheel" (see https://en.wikipedia.org/wiki/Standing_on_the_shoulders_of_giants)
Of course there are important exceptions. If none of the existing models work or have contradictions with each other or with observed data, there may be a need for a new model or a new way of thinking. That's how we got Relativity or Quantum Mechanics.
