Ps in the legacy system were replaced by individually-coded Advanced MAPs (A-MAPs). As shown in Figure 10-2, the control signaling in IEEE 802.16m comprises a superframe header for the broadcast of the essential system configuration information, downlink control channels to carry HARQ feedback, power control signals, the downlink/uplink assignment and allocation information for each user or a group of users, uplink control channels for transmission of channel quality reports, channel state information, bandwidth request, synchronized and non-synchronized ranging, and sounding. Comparison of Figure 10-2 with Figure 10-1 reveals several structural differences between IEEE 802.16m control signaling and that of the legacy. Aside from migration from the concept of joint- coding to individual-coding of the user control channels, the time-relevance of the downlink and uplink assignments have also changed, control channels in the downlink and uplink are frequency- division-multiplexed with traffic channels as opposed to the time-division-multiplex used in the legacy system, and there has been the addition of new control channels such as the superframe header. In the following sections, the physical structure and transmission characteristics of the A-MAPs and the corresponding information elements will be discussed. The detailed description of the uplink control channels will follow in later sections. HARQ Feedback A-MAPs Power Control A-MAPs Non-User-Specific A-MAPs Assignment A-MAPs Guardbands A-MAP A-MAP A-MAP A-MAP A-MAP UL- -Control UL-Control Region Region Region Region Region Region Region A-MAP Region DL Bursts DL Bursts UL Bursts DL Bursts DL Bursts UL Bursts UL Bursts Guardbands Radio Frame = 5 ms P-SFH Subframe PFBCH/SFBCH S-SFH Feedback SP1/SP2/SP3 BW-REQ FIGURE 10-2 Structure of IEEE 802. 16m overhead channels in the downlink and uplink 10.2 Downlink control channels 10.2.1 Physical Structure of Advanced MAPs The Advanced MAP carries unicast control information for the active users in the cell. The unicast co