how i can compute the PD (probability of detection) & PF(probability of false alarm) at the same time by using single threshold in energy detector?? and how can i calculate the threshold in this case??
Threshold are generally calculated as some data or research through an experimentally set layout. For instance, in case of CRN, you can have 2 x USRPs set as transmitter and receiver. You can set centre frequency, sampling technique and bandwidth through the Flow Graph on host-PC connected to USRP.
As regards to Pd, Pmd and Pfa, I would suggest you to go through my conference paper of IEEE WoWMoM 2015.