econdary carrier(s). The initial/periodic ranging procedures with a fully- configured carrier are the same as those for a single-carrier. Periodic ranging may only be performed on the activated secondary carrier(s) on instruction by the BS through the AAI_CM-CMD. The handover ranging is only performed with one of the fully-configured carriers of the target BS. The construction and transmission of MAC PDUs are the same as in single-carrier operation. The ARQ protocol operates based on a common MAC instance. The MAC PDUs are processed in the physical layer similar to that of a single-carrier and are mapped to a data region in one of the primary or secondary carriers. The A-MAP IE corresponding to the allocation is transmitted on the component carrier where the data region is located. Therefore, each component carrier contains its own downlink control channels. In the uplink, the bandwidth requests are transmitted on the mobile station's primary carrier. The bandwidth request may also be transmitted in MAC PDUs over the secondary carrier(s) using the piggyback method [2]. The serving BS may allocate downlink or uplink resources on a specific active carrier or on a combination of multiple active carriers based on available resources, QoS requirements, load balancing, etc. The STID and the associated FIDs assigned to an MS are unique identifiers for the common MAC, and are used on all mobile station's component carriers. The service flow set-up/change messages are transmitted only through the mobile station's primary carrier. The service flow is defined for a common MAC. The BS may assign uplink feedback channels to each fully-configured active carrier with uplink radio resources. When an uplink fast-feedback channel is allocated the MS reports to the CINR for an active carrier over the assigned fast-feedback channel of the corresponding carrier. If the radio resources of a fully-configured carrier are only allocated to downlink transmission, the uplink fast-feedback channel will be located in the uplink control regio