Optionally, if it is a non-interleaved CCE to REG mapping, L=6, one CCE corresponds to one REG group.

Optionally, if it is an interleaved CCE to REG mapping, and the control resource subset includes 1 symbol in the time domain, L=2 or 6, one CCE corresponds to 3 or 1 REG group.

Optionally, if it is an interleaved CCE to REG mapping, and the control resource subset includes 2 symbols in the time domain, L=2 or 6, one CCE corresponds to 3 or 1 REG group.

Optionally, if it is an interleaved CCE to REG mapping, and the control resource subset includes 3 symbols in the time domain, L=3 or 6, one CCE corresponds to 2 or 1 REG group.

Optionally, for an interleaved CCE to REG mapping, the unit of interleaving is the REG group.

The mapping relationship between CCEs and REG groups and the process of mapping a PDCCH to CCEs will be described in detail below in conjunction with specific embodiments.

Taking K=4, N=4, and R=2 as an example, as shown in FIG. 4, the first control resource set includes 4 control resource subsets, for example, control resource subsets 0-3. Each control resource subset includes 12 physical resource blocks (PRBs) in the frequency domain, and 1 symbol in the time domain, for example, one orthogonal frequency division multiplexing (OFDM) symbol. Each small grid in FIG. 4 represents a resource element group (REG), for example, 44 identifies any REG. Assuming that two REGs form a REG group, as shown in FIG. 4, 45 represents any REG group. Optionally, one CCE includes 6 REGs, then one CCE includes 3 REG groups, each control resource subset includes 2 CCEs, and 2 CCEs include 6 REG groups. That is, the first control resource set includes 8 CCEs.