For example, one subframe may be referred to as TTI, a plurality of consecutive subframes may be referred to as TTI, or one slot or one mini slot may be referred to as TTI. That is, at least one of the subframe and TTI may be a subframe (1 ms) in the existing LTE, may be a period shorter than 1 ms (e.g., one to thirteen symbols), or may be a period longer than 1 ms. Note that a unit that represents TTI may be referred to as a slot, a mini slot, and the like, instead of the subframe.

Here, TTI refers to the minimum time unit of scheduling in radio communication, for example. For example, in the LTE system, a base station performs scheduling to allocate radio resources (a frequency bandwidth and transmission power that can be used in each user terminal and the like) to each user terminal in TTI units. Note that the definition of TTI is not limited thereto.

TTI may be a transmission time unit of a channel-encoded data packet (transport block), a code block, a codeword, and the like, or may be a processing unit of scheduling, link adaptation, and the like. Note that, when TTI is given, a time interval (e.g., the number of symbols) in which the transport block, the code block, the codeword, and the like are actually mapped may be shorter than the TTI.

Note that, when one slot or one mini slot is referred to as a “TTI”, one or more TTIs (that is, one or more slots or one or more mini slots) may be the minimum time unit of scheduling. Further, the number of slots (the number of mini slots) constituting this minimum time unit of scheduling may be controlled.