I am looking for a software to simulate RF/CDMA communications between a LEO satellite(s) and a ground antenna station, depending the orbital position and weather conditions if possible.
I am not sure to tell you regarding RF/CDMA simulation, but I can suggest you to search on SNS3 a tool used for satellite communication (it's an NS3 patch) for satellite communication
1. you can use this website they have good calculator... basically they will not simulate but you can use it and break data in parts using this calculator and you can calculate easily...
https://www.everythingrf.com/rf-calculators
2. there is another software for industrial level to use EMW simulator you can ask them for free on request .
https://www.arworld.us/html/software.asp
3. AGI STK for understanding range of transmission