Let {N1(t) t ≥ 0} be a (homogeneous) Poisson process with rate λ = 1, and let {N2(t),t ≥ 0} be a nonhomogeneous Poisson process whose intensity function is
We suppose that the two stochastic processes are independent. Moreover, let {Y(t) t ≥ 0} be a compound Poisson process defined by