“…We start our description on literature review of related works by pointing out some pertinent research works that have employed service delay differentiation approaches as mechanisms of QoS enhancement. We have found very interesting the investigations of Leung et al [44], Tham and Subramaniam [45], Lee et al [46], Li et al [47], Rashid et al [48], Wei et al [49], Bourasa and Sevasti [50], Wu et al [51], Garcia et al [52], Dimitriou and Tsaoussidis [53], Gao et al [54], and Varela et al [55].…”