Patent ID: 8774123

Claim:
A method of operating a wireless communication terminal that is capable of communicating with a base station over a primary carrier and at least one secondary carrier, the method comprising: receiving, at a wireless terminal, one or more downlink control messages transmitted by a base station, wherein each downlink control message contains scheduling information scheduling the wireless terminal to receive a downlink transmission on either a primary carrier or a secondary carrier during a first subframe; determining, for each of the one or more downlink control messages, whether that downlink control message includes scheduling information scheduling the wireless terminal to receive a downlink transmission on the primary carrier or a downlink transmission on a secondary carrier; selecting a format for an uplink control message based on whether any of the one or more downlink control messages includes scheduling information scheduling the wireless terminal to receive a downlink transmission on a secondary carrier; generating an uplink control message based on the selected format, wherein the uplink control message includes feedback information associated with at least one carrier, the feedback information indicating whether the wireless terminal has received a downlink transmission scheduled for the associated carrier; and transmitting the uplink control message to the base station.