ACK) Channel; Bandwidth Request (BW-REQ) Channel; Initial, Periodic, and Handover Ranging Channel; Sounding Channel. Channel quality feedback provides information about channel conditions as seen by the mobile station. This information is used by the BS for link adaptation, resource allocation, power control, etc. The channel quality measurement includes narrowband and wideband measurements. The channel quality 10.3 Uplink control channels HARQ Feedback A-MAP Power Control A-MAP Non-User Specific A-MAP Broadcast Assignment A-MAP IE Assignment A-MAP 1 Assignment A-MAP 2 Assignment A-MAP N AAI_TRF-IND AAI_PAG-IND All data traffic and management messages are composed of a AGMH and a payload AAI_NBR-ADV Payload AAI_TRF-IND Data Burst 1 Data Burst 2 Parameters for TRF-IND FRMT: This parameter indicates the type of Traffic Indication in AAI_TRF- IND control message (SLPID bitmap-based or SLPID-based traffic indication) FIGURE 10-11 An example of usage of broadcast assignment A-MAP IE feedback overhead can be reduced through differential feedback or other compression techniques. Examples of channel quality feedback include Physical CINR, Effective CINR, band selection, etc. Channel sounding can also be used to measure uplink channel quality. MIMO feedback provides wideband and/or narrowband spatial characteristics of the channel that are required for MIMO operation. The MIMO mode, precoding matrix index, rank adaptation information, channel covariance matrix entries, power loading factor, eigenvectors, and channel sounding are examples of MIMO feedback information. HARQ feedback (ACK/NACK) is used to acknowledge downlink burst trans- missions. Multiple codewords in MIMO transmission can be acknowledged in a single ACK/NACK transmission. Uplink synchronization signals are needed to acquire uplink synchronization during initial access or handover, and also to periodically maintain synchronization. Reference signals for measuring and adjusting the uplink timing offset are used for these purposes. Bandwidth requests are sen