An apparatus may include a radio frequency (RF) transceiver to receive a first message over a first carrier in a first band in a downlink sub-frame of a first radio frame in a communications link, where the communications link comprises interband carriers aggregated over primary and secondary cells. The apparatus may also include a processor and a reply message assignment module operable on the processor to determine a downlink sub-frame in which the downlink transmission is received and to adjust timing of a reply/acknowledge message to be sent by the RF transceiver in response to the first message so as to coincide with a predetermined uplink sub-frame of a radio frame. Other embodiments are described and claimed.