how the threshold can be set up in labview for cognitive radio

[ketaki2511]

i have done a coding for threshold selection in labview for cognitive radio..that threshold tells if the signal power of some particular frequency band is less than the threshold then primary user is not present and if its greater than threshold then primary user is present.. but now signalpower can also get reduced because of noise..so what is primary user is present and signal power gets decreased and goes below threshold and secondary user might think that primary user is not present and it starts transmitting then collision can occur..so i have to set two more thresholds below and above the main threshold..how can it be done? how to decise those two thresholds?

[Raname]

Plz i want to ask u smth 

I am working on the same thing u r working on but i have an issue also 

If i have 2 usrp and i am working on labview how can i make the two usrps working one as a tx and the other as a rx not only one of the usrp as a tx and a rx no i need to separate the how i could do this plz ?!!