nistration and maintenance (O&M) systems to gather statistics from all protocols and management planes. These statistics will help network management systems to perform their required functions in a large and complex network deployment. 6.4.3 Protocol Architecture for Broadcast Multicast Service (BCMCS) Figure 6.4 describes the layering architecture for a route of the air interface that carries broadcast-multicast service (BCMCS) data. The architecture consists of physical and BCMCS upper layers and MIB. Each layer or plane consists of one or more protocols that perform the layer's functionality. The physical provides the channel structure, frequency, power output, modulation, and encoding specifications for the BCMCS channel. The BCMCS upper layer consists of multiple protocols to support the transfer IEEE 802.20 Mobile-Fi BCMCS Upper Layer Physical Layer Figure 6.4 BCMCS Route Layering architecture. Reproduced with permission from © 2008 IEEE [4] of information from access network to multiple access terminals. PHY and MAC MIB has the same functionality as described for the unicast route layering architecture. 6.5 Physical Layer Specifications - Wideband Mode This section will briefly touch upon the air interface specifications, primarily physical layer for the Wideband mode and on the key features associated with this mode. 6.5.1 Physical Layer Overview The 802.20 Wideband mode provides physical layer support based on OFDMA for both forward and reverse links. Additionally, Code Division Multiple Access is also supported in the reverse link. The focus in this section is on FDD, the TDD details can be found in [4]. 6.5.1.1 Access Network The transmission on the forward link is performed by various pilot and control channels and by a data channel. The downlink supports two forms of OFDM data transmission namely traditional OFDM and Rotational OFDM. The support of Rotational Orthogonal Frequency Division Multiplexing is optional at the access terminal and the access network. 6.5.1.1.1 Superframe and OFDM Symbol Str