Base station, user equipment and wireless communication method

A user equipment comprising:

• a detector operative to detect a fourth type of downlink control information (DCI) or a second type of DCI in a Physical Downlink Control Channel (PDCCH) region or a starting shortened transmission time interval (TTI) of a subframe;
• and
• circuitry operative to determine whether DCI detected by the detector is the fourth type of DCI or the second type of DCI, wherein:
• if the DCI detected by the detector is the fourth type of DCI, the detector is further operative to detect the fourth type of DCI in one or more shortened TTIs after where the fourth type of DCI is detected for a first time in the subframe;
• if the DCI detected by the detector is the second type of DCI, the detector is further operative to detect a third type of DCI in one or more shortened TTIs after the second type of DCI in the subframe;
• each shortened TTI has 7 or less orthogonal frequency division multiplexing (OFDM) symbols,
• the second type of DCI carries common information for one slot or one subframe, and the third type of DCI carries information specific to a target shortened TTI,
• the circuitry is further operative to form a first type of DCI for the subframe if a normal TTI with 14 OFDM symbols is to be scheduled, and
• the first type of DCI, the second type of DCI and the fourth type of DCI having the same size are differentiable from one another by a two-bit field.