Carrier 1 Carrier 2 Primary Secondary Primary Secondary Carrier Carrier Carrier Carrier FIGURE 11-13 Multi-carrier handover scenarios [2] Serving-BS Target-BS Access Access Network Network Data Communications over Primary Carrier Active Secondary Carrier Active Secondary Carrier AAI_HO-REQ Handover Request for Multiple Carriers Handover Response with Carrier Assignment Information AAI_HO-CMD (Target BS Information) Initial Ranging with Target Primary Carrier Network Re-entry with Target Primary Carrier Primary Carrier Established Secondary Carrier Established Secondary Carrier Established FIGURE 11-14 Multi-carrier handover with secondary carrier pre-assignment 11.5 3GPP LTE-Advanced multi-carrier operation transitions to sleep mode. The sleep mode parameters are applied to all mobile station's active carriers. Note that the serving BS may request the MS to change its primary carrier on entering the sleep mode or during the listening window using an AAI_CM-CMD message for load balancing or power conservation. In the beginning of the listening window, data transmission is permissible on all the active carriers assigned to the MS. The MS monitors the traffic indication message on its primary carrier. On receiving a negative traffic indication in the traffic indication message, the MS resumes the sleep cycle. If a positive traffic indication is received, the MS begins to receive data on one or more active carriers. If the traffic indication is disabled, data transmission and scheduling will be the same as in normal operation during the listening window. In this case, the MS monitors the active carriers during the listening window, and the BS may allocate downlink data on the primary carrier and the active secondary carriers. If the traffic indication is disabled and downlink data transmission on the active secondary carriers is complete, the BS may instruct the MS to stop data transmission on the active secondary carriers through the sleep control header, which is transmitted in the primary carrier during listening 