s, such as operation over one RF channel at a time or aggregation across contiguous or non-contiguous frequency bands. 3.2.4 Protocol Structure for Support of Multicast and Broadcast Services Multicast and broadcast service is a point-to-multipoint communication scheme where data packets are transmitted simultaneously from a single source to multiple destinations. The term broadcast refers to the ability to deliver content to all users. Multicast, on the other hand, refers to distribution of content among a specific group of users that are subscribed to those services. The multicast and broadcast content is transmitted over a geographical area referred to as a zone. An MBS zone is a collection of one or more base stations transmitting the same content. Each BS capable of MBS service may belong to one or more MBS zones. Each MBS zone is identified by a unique zone identifier [3]. An MS can receive the MBS content within the MBS zone in connected state or idle state. A BS may provide multicast and broadcast services corresponding to different MBS zones. The MBS data bursts may be transmitted in the form of several sub-packets, and these sub-packets may be transmitted in different time intervals to allow the MS to combine the sub-packets without transmission of acknowledgement. The mobile stations in an MBS zone are assigned a common multicast station identifier. The IEEE 802. 16m supports two types of MBS access: (1) single-BS; and (2) multi-BS. The single-BS access is implemented over multicast and broadcast transport connections within one BS, while multi-BS access is realized by transmitting MBS data through multiple base stations. The MBS PDUs are transmitted by all base stations in the same MBS zone. That transmission is supported either in the non-macro diversity mode or macro diversity mode. An MBS zone may be formed by only one E-MBS Zone E-MBS Session Configuration Management E-MBS Transmission E-MBS Mobility E-MBS Function Management Configuration E-MBS Control Signaling FIGURE 3-19 Breakdown of the E-MBS