Observation 1 3 a() z 5月z N() Delay t custom B() custom I Shaded Area N(Tdt= [a(t)-Bcoldt 0Communication Networks Number of Arrivals a(t) Number of Departures b(t) custom 1 Delay T1 custom 2 Delay T2 a(t) b(t) N(t) t t Observation 1 8 Shaded Area = න 0 𝑡 𝑁 𝜏 𝑑𝜏 = න 0 𝑡 𝛼 𝜏 − 𝛽 𝜏 𝑑𝜏