Base station, user equipment, and method

A method used in a base station performing a radio communication with a user equipment, comprising:

• determining a transmission format of a downlink data channel not to be associated by a control channel, based on a downlink reception signal quality measured by the user equipment;
• notifying, to the user equipment, the transmission format determined by the transmission format determining unit;
• and
• transmitting downlink data to the user equipment via the downlink data channel, by using the transmission format determined by the transmission format determining unit.

A user equipment performing a radio communication with a base station, comprising:

• a measurement unit configured to measure a downlink reception quality;
• a determining unit configured to determine whether or not to change a transmission format of a downlink data channel, based on the downlink reception signal quality that is measured;
• a notification unit configured to notify, to the base station, a change request for the transmission format;
• an extracting unit configured to extract information of the transmission format notified by the base station;
• and
• a receiving unit configured to receive downlink data transmitted via a subsequent downlink data channel by using the transmission format that is extracted.

A method used in a user equipment that performs a radio communication with a base station, comprising:

• measuring a downlink reception quality;
• determining whether or not to change a transmission format of a downlink data channel, based on the downlink reception signal quality that is measured;
• notifying, to the base station, a change request for the transmission format;
• extracting information of the transmission format notified by the base station;
• and
• receiving downlink data transmitted via a subsequent downlink data channel by using the transmission format that is extracted.