In FIG. 1, a horizontal axis represents a time domain and a vertical axis represents a frequency domain. In the time domain, the minimum transmission unit is an OFDM symbol, and Nsymb 101 OFDM symbols are gathered to constitute one slot 102, and two slots are gathered to constitute one subframe 103. The length of the slot is 0.5 ms, and the length of the subframe is 0.1 ms. Further, a radio frame 104 is a time domain unit including 10 subframes. In the frequency domain, the minimum transmission unit is a subcarrier, and a bandwidth of an entire system transmission band includes a total of NBW subcarriers 105. In the time-frequency domain, a basic unit of a resource is a resource element (RE) 106, and may be indicated by an OFDM symbol index and a subcarrier index. An RB or a physical resource block (PRB) 107 is defined by Nsymb consecutive OFDM symbols 101 in the time domain and NRB consecutive subcarriers 108 in the frequency domain. Accordingly, one RB 108 includes Nsymb x NRB REs 106. Generally, the minimum transmission unit of data is an RB unit. In the LTE system, generally, Nsymb=7, NRB=12, and NBW and NRB are proportional to the bandwidth of the system transmission band.
Next, DL control information (DCI) in an LTE system and an LTE-A system will be described in detail.
