ame Location of the Uplink Control Region in FDD Frame Structure FIGURE 11-9 An example of allocation of uplink control channels corresponding to downlink-only component carriers CHAPTER 11 Multi-Carrier Operation aggregation scenario. When MAC control messages such as the AAI_SingleBS_MIMO_FBK AAI_MultiBS_MIMO_FBK, MIMO feedback header, and correlation matrix feedback header are used for downlink CINR reporting, they are transmitted on the mobile station's primary carrier. The Feedback Polling A-MAP IE is used to notify an MS of an uplink burst region and is transmitted on each active downlink carrier. 11.4.1 Activation/Deactivation and Switching of Component Carriers The activation or deactivation of secondary carriers is determined by the BS based on service flow QoS requirements, the loading status of the active carriers, channel quality measurements for active carriers, and a scan report for inactive carriers. The trigger condition associated with each carrier can be obtained via the AAI_SCD control message, which is broadcast on the primary carrier of the MS. The BS activates or deactivates secondary carriers using the AAI_CM-CMD MAC control message transmitted on the primary carrier. The latter control message includes activation/deactivation indi- cators, a list of secondary carriers referenced by their physical carrier indices, ranging parameters for the activated carriers, and the time for the MS to confirm activation of the secondary carrier by sending the AAI_CMD-IND message before expiration of the activation. When an MS with a single radio transceiver goes through secondary carrier activation, the MS reconfigures its RF front-end and baseband parameters, based on the characteristics of the activated carrier. Once the hardware reconfiguration is complete and the MS is synchronized with the new carrier, the BS is notified of the MS preparedness by sending an AAI_CM-IND control message. After the BS receives the AAI_CM-IND control message, it starts data transmission on the newly activated secondary ca