Since the first polling model appeared in the late 1950s, when the papers of Mack et al. concerning a patrolling repairman model for the British cotton industry were published, few models have received much attention. The ubiquity of polling systems can be observed in many applications, e.g., computer-communication, production, transportation, maintenance systems, traffic and transportation systems and so on. A huge part of the queueing literature is devoted to polling models both in applications and in the mathematical analysis. Specially, polling systems find a wealth of applications in the area of wireless communication systems media access control, where resources (e.g., bandwidth) are shared among different users without traffic collision. With the enhancing of users demand on network quality, performance and QoS assurance are becoming crucial in protocol design, especially in MAC layer. Correspondingly, polling models for protocol mathematics analysis are demanded to provide priority differentiation and delay guaranteed.