passband signal
modulated signal
Because a modulated signal can encode information in the amplitude, frequency, or phase of the carrier wave, it is
s(t)=α(t)cos(2π(fc+f(t))t+θ(t)+ϕ0)
Alternatively,
s(t)=ℜ{u(t)ej2πfct}
where u(t)=sI(t)+jsQ(t).