“…The signal energy values ( E total ) stored in FC are classified into four different classes, ie, PU signal presence in absence of PUEA, PU signal presence in presence of PUEA, PUEA signal presence in absence of PU, and noise only. The classes, as mentioned earlier, are shown in Figure using four different membership functions, namely, Z(x, α , β )‐function, ‐function, ‐function, and S(x, α , β )‐function, respectively. Based on the energy values of PU and PUEA signals in radio mobile environment, such distinctive regions are less likely to obtain.…”