My Research field is MAC protocols for Wireless sensor network. you have a lot of choice for implementing a MAC protocols . Most of the researchers use ns-2 or Omnet for simulation a wireless sensor network specially MAC protocols.
In addition, I recommend you a new simulator which is based on Omnet. it's Castalia.
Please refer to this link http://www.researchgate.net/profile/Adib_Rastegarnia/blog/8432_What_is_Castalia
I will see. I am making some wake up hardware for wireless sensor nodes.
so, i have to compare my model with MAC protocols.
In Omnet, Can i get some MAC protocols or i have to write the codes for mac protocols (like S-MAC, B-MAC, O-MAC) then I could be able to compare with my hardware.
Some of the MAC protocols have been implemented in Omnet previously ( such as SMAC and TMAC ) . But you should implement your protocol to compare it with other protocols in different parameters such as power consumption, delay and etc.