In communication systems where the channel is expected to vary during a communication burst, gain adjustments during the communication burst can be implemented by automatic gain control (AGC) in the receiver, with minimal performance degradation. These gain adjustments are successfully accommodated by virtue of suitable information-sharing between an AGC unit and a digital baseband part. The digital baseband part can direct the AGC unit appropriately to ensure that gain adjustments are implemented during time intervals that do not carry substantive communication information (e.g., guard intervals). In receivers that perform channel estimation in the digital baseband part, the AGC unit supports channel estimation by informing the digital baseband part about the timing of the gain adjustment. The AGC unit can also support channel estimation by informing the digital baseband part about the size of the gain adjustment.