Plz help me UHF RFID simulation

Hi everybody!
I am newbie to RFID technology, i really need your kind help.
I am doing the thesis about Electronic Road Pricing using RFID. And i wonder about the method to design this system.
At the first step, I think I should use semi-passive UHF RFID, so we can solve the requirement of farfield and the speed of vehicle.
But to design the system, i don't know which software i can use to simulate the UHF RFID system. Would you please give me some advice of the aproaching method ...

anyone help me? the software simulate RFID?

Your question is not easy, as I far not on the market is not sw that will be able to analyze RFID system as a complex system . There is a lot of questions.
You have to split your task on some parts.
Create EM field on the base of your antennas , create model of vehicles , probability of moving vehicles, analyze of possition of vehicles , optimalization ...etc