 function (control-plane) [12] 3.3 3GPP LTE/LTE-advanced protocol structure BS. The MS may support both single-BS and multi-BS access. The MBS service may be delivered via a dedicated RF carrier or a mixed unicast, multicast, and broadcast RF carrier. The IEEE 802.16m Enhanced Multicast and Broadcast Service (E-MBS) consists of MAC and PHY protocols that define interactions between the mobile stations and the base stations. While the basic definitions of IEEE 802.16m E-MBS are consistent with that of the IEEE 802.16-2009 standard [3], some enhancements and extensions are incorporated to provide improved functionality and performance [12]. The breakdown of E-MBS MAC function into constituent components is shown in Figure 3-19. In the control-plane, E-MBS MAC function operates in conjunction with other unicast service MAC functions. The unicast MAC functions may operate independently from E-MBS MAC function. The E-MBS MAC function may operate differently depending on whether it is operating in active mode or idle mode [12]. The E-MBS MAC function consists of the following sub-blocks: E-MBS Zone Configuration: this function manages the configuration and advertisement of E-MBS zones. A BS may belong to multiple E-MBS zones. E-MBS Transmission Mode Configuration: this function describes the transmission mode in which E-MBS is delivered over the air interface such as single-BS and multi-BS transmission. E-MBS Session Management: this function manages E-MBS service registration and deregistration and session start, update, or termination. E-MBS Mobility Management: this block manages the zone update procedures when an MS crosses the E-MBS zone boundary. E-MBS Control Signaling: this block broadcasts the E-MBS scheduling and physical channel mapping to facilitate E-MBS reception and power saving. 3.3 3GPP LTE/LTE-ADVANCED PROTOCOL STRUCTURE In this section, we provide an overview of 3GPP LTE/LTE-Advanced protocol structure. Figures 3-20 and 3-21 illustrate the user-plane (U-plane) and control-plane (C-plane) protocol sta